Title of Invention

PYRAZOLYL-SUBSTITUTED TRIAZOLOQUINOXALINES

Abstract According to the invention, derivatives of pyrazolyl[1,2,4]triazolo[4,3- a]quinoxaline according to formula I or the analog in the form of pyrazolyl-substituted tetrazolo[1,5-α]quinoxalines according to formula II are indicated. The substances according to formula 1 or 2 are suitable in this form or in the form of their pharmaceutically compatible salts as active ingredients, in particular as adenosine receptor ligands.
Full Text Pyrazolyl-Substituted Triazoloqninoxalines
The invention relates to pyrazolyl-substituted triazoloquinoxalines, their analogous
tetrazoloquinoxalines as well as their pharmaceutically compatible salts, their production as well
as their use as pharmaceutical agents for treating diseases in the kidney area (as K+-saving
diuretic agents, for acute renal failure, for nephritis, for hepatorenal syndrome); for treating the
heart (preferably in the case of cardiac irregularities, ischemia, myocardial infarction or angina
pectoris); the central nervous system (for dementia, Alzheimer's disease, anxiety disorders,
epilepsy, Parkinson's disease, stroke, depression, opiate withdrawal and comatose conditions);
and for treating the lungs (for therapy of respiratory diseases, for example asthma, bronchitis and
mucoviscidosis as well as protective agents for a lung transplant). In addition, the invention
comprises pharmaceutical agents for treating hypertension, allergic skin diseases (urticaria),
inflammations, as immunostimulants, for reducing sperm motility, from which a contraceptive
action is derived, as well as diagnostic agents.
Prior Art
It is known that the nucleoside adenosine is a modulator that is ubiquitous in mammals,
including humans, and said modulator is bonded extremely tightly to the energy balance in the
form of its di- and triphosphates. Adenosine itself has an effect on the nervous system, the
cardiovascular system, the immune system, the respiratory system and the metabolism, whereby
these actions are in general of a suppressive nature, i.e., the actions are sedative, vasodilative,
slow the heart frequency and inhibit the diuresis as well as the lipolysis.
To date, four different adenosine receptors have been identified that activate the adenylate
cyclase via coupling to protein G and bear the names A1, A2A, A2B and A3. The central nervous
system exhibits especially high densities of adenosine receptors, but in particular A1- and A2B-
receptors are found in almost all tissue types. Because of their varied importance in medical
physiology as well as pharmacology, adenosine receptors are in many cases subjects of detailed,
scientific survey articles (see, e.g., K. N. Klotz, Naunyn Schmiedebergs Arch. Pharmacol, 362,

382-91 (2000); P. G. Baraldi et al, Med. Res. Rev., 20, 103-28 (2000); C. E. Müller, Farmaco,
56, 77-80 (2001), etc.). While receptor subtypes A1 and A2A are highly affine and are stimulated
by adenosine already in nanomolar concentrations, subtypes A2B and A3 exhibit low
(micromolar) affinity to natural ligands. On this basis, considerations of staggered activation of
these receptors by increasing adenosine concentrations were advanced, whereby A1-receptors
provide the basal activation in physiological dormant concentrations, and A3-receptors primarily
exert their action for exceptional cases with greatly increased adenosine concentrations, for
example for ischemic stroke or myocardial infarction.
Adenosine A1-receptors are thus almost constantly activated according to this model
presentation and exert a tonic inhibitory monitoring that can be eliminated by antagonists; this is,
e.g., the pharmacological basis of the enlivening and dehydrating action of caffeine. Adenosine
A1-antagonists are therefore extremely advantageous as pharmacological active ingredients in
many respects:
- Within the scope of psychiatry for promoting the cognition for dementia conditions and
as antidepressants;
- In the cardiovascular and urological areas as antihypertensive agents and antiarrythmic
agents;
- For the therapy of acute renal failure, in which adenosine A1-blocking eliminates the
secondary vasoconstriction and can increase the blood supply. Here, the independent
diuretic effect, especially the promoting of the potassium-saving natriuresis from A1-
antagonists is of additional importance, since water retention results in a further increased
stress on the circulatory system.
- In the lungs, adenosine A1-antagonists can counteract a bronchoconstriction that is
mediated via activation of A1-receptors by relaxation of the smooth tracheal muscles;
there are therefore potential anti-asthmatic agents. Since these active ingredients promote
the ejection of chloride ions from the epithelial cells there, moreover, a positive action on
the clinical picture of the mucoviscidosis is discussed.

In a remarkable manner, the activation of the A2A-receptors in the brain as well as in the
retina of the eye has an antagonistic effect on the A1-receptors. A2A-antagonists, which are
brought into connection with the modulating action of the adenosine on the release of various
neuropeptides, metabotropic and ionotropic glutamate, dopamine and nicotine receptors, which
in turn again influence the release of acetylcholine and dopamine, as well as with the release of
gamma-aminobutyric acid (GABA) (J. A. Ribeiro, Eur. J. Pharmacol, 375, 101-113 (1999)),
and represent potential therapeutic agents for the treatment of Parkinson's disease, can therefore
potentiate the action of cerebral A1-agonists (F. Pedata et al., Ann. N. Y. Acad. Sci., 939, 74-84
(2001)). The latter represent potential active ingredients for the therapy of stroke patients and
patients with retinal ischemia. Whether, however, adenosine A2A-agonists can eliminate the
action of adenosine A1-inhibitors, however, is still not known at this time. Ligands with
comparable bonding strength to A1- and A2A-receptors are considered undesirable, however,
since the resulting pharmacological actions could be directed against one another.
It is known that adenosine receptor antagonists with a purine or xanthine partial structure
exhibit neither adequate affinity nor selectivity. These parameters could, hov/ever, be
significantly improved, for example by using 2-furanyl derivatives of the triazoloquinazoline,
triazolopyrimidine and triazolotriazine with the following structural formulas (E. Ongini et al,
Naunyn Schmiedebergs Arch. Pharmacol, 359, 7-10 (1999) and Farmaco 56, 87-90 (2001):

9-Chloro-2-(2-furanyl)-[1,2,4]triazolo[l,5-c]quinazoline-5-amine


2-(2-Furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine-5-amine

4-[2-[[7-Amino-2(2-furanyl)[1,2,4]triazolo[1,5-a][1,3,5]triazin-5-yl]amino]ethyl]-phenol
The cited examples, however, have different pharmacological or (physico)chemical
drawbacks. The development of compound CGS-15943 as a therapeutic agent for ischemic
stroke was thus halted because of inadequate selectivity. The compound Sch-52861, however,
has a very high receptor affinity and good selectivity (KiA2A = 2.3 nm; KiAI = 121 nm), but the
inadequate solubility and poor oral bioavailability limit the pharmaceutical suitability. The
compound ZM-241385, which even has a selectivity factor of about 400, is used only as a
tritated radioligand for visualization of A2A-receptors in the animal test.
In addition to other triazolo[1,5-c]quinazolines and triazolo[1,5-c]pyrimidines,
triazolo[4,3-a]quinoxalines were also examined. The fact that, on the one hand, 4-amino-6-
benzylamino-1,2-dihydro-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one represents a selective
A2A-antagonist (V. Colotta et al, Arch. Pharm. Pharm. Med. Chem., 332, 39-41 (1999), and, on
the other hand, 8-chloro-4-(cyclohexylamino)-1-(trifluoromethyl)[1,2,4]triazolo[4,3-
a]quinoxaline (CP-68,247) exerts a highly selective antagonistic action on the A1-receptor (IC50
value is 28 nmol) (R. Sarges et al, J. Med. Chem., 33, 2240-2254 (1990)), clearly shows how
closely these pharmacologically opposite actions lie to one another in this compound class. For
all of these compounds, agonistic or partially agonistic action on the respective receptors is
excluded, since such a one requires an intact nucleotide structure according to the present state of
knowledge, but in any case an essentially intact ribose unit (C. E. Miiller and B. Stein, Curr.

Pharm. Design, 2,501-530 (1996) and literature cited therein).
Compounds with the following base are also known from the literature (B. Matuszczak et
al, Arch. Pharm. Pharm. Med. Chem., 331, 163-169 (1998)).
Also in this substance class, a dependence of the subtype-affinity on the substituent in 1-
position was shown. While the 1-methyl derivative shows a higher affinity to the adenosine A2A-
receptor than to the A1-receptor (A2A: Ki = 1.43 µm; A1: Ki = 7.85 µm, i.e., the selectivity factor
is about 5), preference for the adenosine A1-receptor is provided in the case of the other
derivatives (for R = 2-thienylmethyl: KiA1 — 200 nm). A comparison of the absolute values of
the binding affinity to that of other adenosine receptor antagonists shows, however, that the
compounds of this type are inferior in this connection and therefore in all probability are not
suitable as pharmaceutical agents.
Presentation of the Invention
The object of this invention is to further increase the receptor activities of the initially
mentioned pyrazolyl-substituted triazoloquinoxalines as well as their analogs in the form of
tetrazoloquinoxalines.
According to the invention, triazoloquinoxalines of general formula (I) with Y = CR, in
particular 4-(chloropyrazolyl)-1-(3-phenylpropyl)-[1,2,4-]triazolo[4,3-a]quinoxaline as well as
tetrazoloquinoxalines of general formula (2) with Y = N in


are proposed, in which Rl to R4 are hydrogen, linear or branched, saturated or unsaturated alkyl
radicals, cycloalkyl radicals, which optionally have one or more heteroatoms, aryl or heteroaryl
radicals, alkoxy, hydroxy, halogen, amino, nitro, trihalomethyl, carboxy, alkoxycarbonyl or sulfo
groups, whereby Rl to R4 are identical or different or can be present as fused aryl or heteroaryl
radicals or as correspondingly hydrogenated or partially hydrogenated systems, and in which
substituent R is hydrogen or a linear or branched-chain, saturated, and/or unsaturated carbon
radical, a cycloalkyl radical, an aryl or heteroaryl radical in substituted or unsubstituted form,
whereby substituent R is bonded to the base either directly or via an alkylene group, in which one
or more carbon atoms can be replaced by heteroatoms, such as oxygen, sulfur or nitrogen, and in
which substituent R5 is hydrogen, C1-C8 alkyl, allyl, arylalkyl, (hetero) arylalkyl or acyl, and in
which radical R6 is a halogen or hydrogen, excluding compounds with Rl to R5 equal to
hydrogen, R6 equal to chlorine and R equal to methyl, phenyl, benzyl, 2-furyl, 2-thienyl or 2-
thienylmethyl.
The first structure-activity relationships, which could be set up for this substance class,
were in accordance with a pharmacophore model for A1 antagonists that was described in the
literature (B. Matuszczak etal, Arch. Pharm. Pharm. Med. Chem., 331, 163-169 (1998)). These
results suggested that the structure-activity relationships of standard A1-ligands are to be
transferred to these tricyclic compounds. It should thus be possible, with the aid of known
pharmacophore models, to develop compounds with improved receptor affinity as well as
improved subtype selectivity.
It was shown, surprisingly enough, however, that the receptor affinities were no longer to
reconcile other derivatives with the pharmacophore models. The finding that unchanged receptor
affinity was provided after removal of individual structural components, which up until this time
had been considered as essential to the design of the interactions of the ligand with the receptor,
shows that an analogy with respect to the binding to the receptor is not given and thus structure-
affinity relationships also cannot be transferred from other substance classes to these compounds.
Pharmacophore models that are known in the literature thus also cannot be used in these

pyrazolyl-substituted tricyclic compounds; this compound class is rather to be considered as a
completely new invention.
Especially based on the pharmacophore and receptor model that is known in the
literature, it was not to be expected that the compounds according to the invention show an
affinity and selectivity to adenosine receptors, which makes them suitable to a large extent for
use as pharmaceutical agents in terms of subtype-specific adenosine antagonists.
Analogs that are considered within the scope of the invention are, in the same way
starting from general formulas (1) and (2), those compounds in which in each case independently
of one another, it holds true that substituents Rl to R4 are hydrogen, linear or branched, saturated
or unsaturated alkyl radicals, such as, for example, methyl, ethyl, propyl, butyl, isobutyl, allyl, or
cycloalkyl radicals, whereby optionally one or more carbon atoms can be replaced by nitrogen,
oxygen or sulfur, aryl or heteroaryl, alkoxy, hydroxy, halogen, amino, nitro, trihalomethyl,
carboxy, alkoxycarbonyl or sulfo groups, whereby substituents R1 to R4 can be identical or
different.
Substituent R can be hydrogen or an organic radical such as an alkyl, cycloalkyl, aryl or
heteroaryl substituent, which is bonded to the base either directly or via an alkylene bridge, in
which one or more carbon atoms can be replaced by heteroatoms, such as oxygen, sulfur or
nitrogen.
As an organic radical, a linear or branched-chain C1- to C6-alkyl group, for example
methyl, ethyl, propyl, butyl, or isobutyl, is preferred. This alkyl chain can also be substituted in
turn, for example, with halogen, alkoxy, hydroxyl, amino - unsubstituted or substituted with one
or two alkyl, aryl or acyl radicals--, alkoxycarbonyl, carboxyl, sulfo or cyano. In addition, this
substituent can also contain one or more double or triple bonds, as is the case, for example, in
allyl groups.
In addition, the organic radical can be a cycloalkyl substituent with the ring size that
consists of three to eight carbon atoms. One or more carbon atoms in the ring can be replaced
from heteroatoms, such as, for example, nitrogen, oxygen, or sulfur; moreover, the ring (for

example, a piperazine, JV-methylpiperazine, morpholine, dioxolane, dioxane, adamantane or
noradamantane radical) can also be further substituted.
Further, an aryl or heteroaryl (for example furyl, thienyl, or pyridyl) radical is also
preferred as an organic radical. The hetero(aryl) radical can optionally carry one or more
substituents. As substituents of interest, in particular halogen, unsubstituted or else substituted
alkyl - as an example of a substituted alkyl of interest, for example, trifluoromethyl, alkoxy,
hydroxy, unsubstituted or substituted - for example also acylated - amino, alkxoycarbonyl,
carboxyl, sulfo, nitro and cyano are used.
Substituent R5 can be hydrogen, a linear or branched alkyl, allyl, (hetero)arylalkyl, or acyl
group. This substituent is found on one of the nitrogen atoms of the pyrazole ring.
Radical R6 can be either halogen, such as fluorine, chlorine, or bromine, or else
hydrogen.
In addition, the invention relates to a process for the production of compounds (1) and
(2), as well as pharmaceutical agents that contain the latter, as is disclosed according to the
claims.
Methods for Implementing the Invention
In reference to the prior art, some possible variations are explained in the following
experimental portion. These examples are used only for illustration, without, however, thus
limiting the invention to this scope.
I. Process for the Production of Compounds According to Formula (t) While Varying
Substitnents R and R1 to R4
I.1 Symmetrically-Substituted Derivatives


[Key:]
Hydrazin = Hydrazine
Acylierung = Acylation
Cyclisierung = Cyclization
X and X' are the same radical or different radicals of the above-cited definition with the
limitation X' = halogen, whereby in general formula (I), X also has the meaning of R6.
R, R1, R2, R3 and R4 can be defined according to the above-cited descriptions.
The synthesis sequence that is shown allows not only access to compounds in which the
carbocyclic portion of the quinoxaline is unsubstituted, but also makes possible the production of
symmetrically substituted compounds of the following type:

a) R1 to R4 = identical substituents1;
b) R1 and R4 = identical substituents and R2 and R3 = H;

c) R2 and R3 = identical substituents and R1 and R4 = H;
d) R2 and R3 = identical substituents and R1 and R4 = identical substituents
The necessary symmetrically-substituted ortho-phenylenediamines can be purchased, are
described in the literature or are synthetically available analogously to the derivatives that are
described in the literature. Nitration reactions and subsequent reduction reactions are of special
importance in the production of the substituted phenylenediamines.
The production of such symmetrically substituted compounds (with X = C1 and
R1 = R4 = H and R2 = R3 = CH3) is to be explained based on the dimethyl derivatives. The
substance class that is selected for this purpose or the cited examples are used, however, only for
illustration, without the invention being limited to their scope.
Below, synthesis examples are indicated for the production of the compounds that are
shown in synthesis diagram 1:
Synthesis of N-[2-Amino-4,5-dimethylphenyl)-3,6-dichloropyridazine-4-carboxamide* (C-1)

1In this case, substituent means R ≠ H
* Already described in: M. Banekovich, 'Pyrazolyl-substituierte Chinoxaline: Darstellung neuer
potentieller serotoninrezeptor-Liganden und Untersuchungen zum Fluoreszenz-Verhalten
[Pyrazolyl-Substituted Quinoxalines: Production of New Potential Serotonin Receptor Ligands
and Studies on Fluorescence Behavior],' University Thesis, Innsbruck, 1998.

A solution that consists of 5.402 g (25.55 mmol) of 3,6-dichloropyridazine-4-carboxylic
acid chloride in 60 ml of absolute dichloromethane is slowly added in drops to a suspension that
consists of 10.440 g (76.65 mmol, 3 equivalents) of 4,5-dimethyl-o-phenylenediamine and 25.55
mmol of base (for example, triethylamine, pyridine, Hiinig base, or the like) in 150 ml of
absolute dichloromethane at 0°C under nitrogen atmosphere. Then, the reaction batch is stirred
until the reaction of the acid chloride is completed at room temperature (about 16 hours; TLC
(thin-layer chromatogram) monitoring: several drops of the reaction batch are mixed with dilute
hydrochloric acid, the solution is neutralized with saturated sodium bicarbonate solution and
extracted with ethyl acetate, mobile solvent: ethyl acetate). The crystals that are produced are
filtered off by suction, washed with dichloromethane and dried in a desiccator until a constant
weight is reached.
The filtrate is extracted three times with 200 ml each of ice-cooled dilute sodium
hydroxide solution, the aqueous phase is washed with dichloromethane and then acidified with
concentrated hydrochloric acid while being cooled with ice. The resulting precipitate on
diacylated product is filtered off by suction, the aqueous phase is washed twice with
dichloromethane and then neutralized with saturated sodium bicarbonate solution. The neutral
solution is exhaustively extracted with dichloromethane. The combined organic phases are
washed with saturated sodium chloride solution, dried on sodium sulfate, filtered off and
evaporated to the dry state.
For further reaction, the product (light yellow crystals) of the composition C13H12CI2N4O
(311.17) (yield: 90%) exhibits adequate purity.
Melting point: Starting from 198°C decomposition
Elementary analysis: C H N
Cld. 50.18% 3.89% 18.01%
Fnd. 50.22% 4.12% 17.96%
IR (KBr): 3386, 3183, 3012, 1673 cm-1
1H-NMR (DMSO-d6) 9.92 (s, 1H, NH), 8.47 (s, 1H, pyridazine H5), 7.01 (s, 1H), 6.57 (s,

1H) (H5, H6), 5.10 (s, br, 2H, NH2), 2.10 (s, 3H, CH3), 2.08 (s, 3H,
CH3).
Synthesis of 3-[3(5)-Chloro-1H-pyrazol-5(3)-yl]-6,7-dimethylqninoxalin-2( 1H)one* (D-1)

3 equivalents of base (preferably sodium hydride, 60% dispersion) is added to a solution
that consists of 2.000 g (6.44 mmol) of N-(2-amino-4,5-dimethylphenyl)-3,6-dichloropyridazine-
4-carboxamide (C-1) in 50 ml of anhydrous solvent (for example N,N-dimethylformamide) under
nitrogen atmosphere, and the reaction mixture is stirred until the reaction is completed at 100°C
(the reaction time is about 15 minutes; for reaction monitoring, several drops of the reaction
batch are mixed with dilute hydrochloric acid and extracted with ethyl acetate, mobile solvent:
ethyl acetate; the complete reaction can be detected in addition in the color change of the reaction
solution from dark red to brown).
For working-up, the reaction solution, while being exposed to nitrogen gassing, is
carefully added to dilute hydrochloric acid. The accumulating product that is crystalline in this
case is isolated and washed with water as well as petroleum ether and then dried until a constant
weight is reached. The purification of the crude product is carried out by treatment of a solution
of the substance in tetrahydrofuran with activated carbon in the heat, filtration and distillation of
the solvent. The thus obtained product (yellow crystals) of the composition C13H11C1N4O
(274.71) (yield: 95%) has an adequate purity for the additional reaction.
Melting point: 328°C while being decomposed
Elementary analysis: C H N
Cld. 56.84% 4.04% 20.39%
Fnd. 56.75% 4.34% 20.12%

IR(KBr): 3311,1666 cm-1
1H-NMR (DMSO-d6) 13.65 (s, 1H, pyrazole NH), 12.60 (s, 1H, quinoxaline NH), 7.51
(s, 1H, quinoxaline CH, 7.15 (d, J = 1.4 Hz, 1H, pyrazole-CH),
7.07 (s, 1H, quinoxaline CH), 2.29 (s, 3H, CH3), 2.27 (s, 3H, CH3).
Synthesis of 2-Chloro-3-[3(5)-choloro-1H-pyrazol-5(3)-yl]-6,7-dimethylquinoxaline* (E-1)

A suspension that consists of 2.601 g (9.47 mmol) of the corresponding quinoxalin-2-one
derivative (D-1) is refluxed in a mixture that consists of 50 ml of phosphorus oxychloride and 5
ml of pyridine until the reaction is completed (about 3 hours; TLC monitoring: several drops of
the reaction batch are mixed with saturated sodium bicarbonate solution and extracted with ethyl
acetate, mobile solvent: ether). After cooling, the reaction mixture is carefully added to ice
water. To improve the crystallization, for example, some saturated sodium bicarbonate solution
is added. The precipitate is separated and washed with water as well as petroleum ether and
dried in the desiccator until a constant weight is reached. For purification, a solution of the crude
product in tetrahydrofuran is mixed with activated carbon, and this mixture is briefly heated to
boiling, filtered off and evaporated to the dry state in a Rotavapor. The thus obtained product
(beige-colored needles) of the composition C13H10Cl2N4 (293.16) exhibits an adequate purity for
the additional reaction (yield: 1.868 g (67%)).
Melting point: 296-3 00°C
Already described in: M. Banekovich, 'Pyrazolyl-substituierte Chinoxaline: Darstellung never
potentieller Serntoninrezeptor-Liganden und Untersuchungen zum Elunnreszenz-Verhalten'
University Thesis, Innsbruck, 1998

Elementary analysis: C H N
Cld. 53.26% 3.44% 19.11%
Fnd. 53.39% 3.61% 19.23%
IR (KBr): 3226 cm-1
1H-NMR (DMSO-d6) 13.96 (s, 1H, pyrazole NH), 7.89 (s, 1H, quinoxaline CH, 7.84 (s,
1H, quinoxaline CH), 7.19 (s, 1H, pyrazole-CH), 2.50 (s, 6H, 2x
CH3).
Instead of a chloroquinoxaline (E), other derivatives can also be used for additional
synthesis of compounds of type (F), in which the chlorine atom is replaced by another leaving
group, for example by bromine, iodine or mesylate.
Instead of 3-[3(5)-Chloro-1H-pyrazol-5(3)-yl]-6,7-dimethyl-2-hydrazinoquinoxaline (F-1)

1.061 g (3.62 mmol) of the corresponding chloroquinoxaline derivative (E-1) is
suspended in 20 ml of hydrazine monohydrate, and the mixture is refluxed until the reaction is
completed (about 2 hours; TLC monitoring: several drops of the reaction batch are mixed with
water and extracted with ethyl acetate, mobile solvent: ethyl acetate). After cooling, the reaction
mixture is added to 150 ml of water, and to complete the crystallization, the resulting suspension
is allowed to stand for several hours at about 4°C. The crystals are then isolated and washed with
water as well as petroleum ether. After drying until a constant weight is reached, the crystals are
dissolved in tetrahydrofuran, the solution is mixed with activated carbon and heated briefly to
boiling, filtered, and evaporated to the dry state at reduced pressure. The product that is obtained
(yellow powder) of composition C13H13C1N6 (288.74) exhibits an adequate purity for the
additional reaction; analytically pure compound is obtained by recrystallization from

tetrahydrofuran.
Yield: 0.629 g (82%)
Melting point: 281 -283°C
Elementary analysis: C H N
Cld. 54.08% 4.54% 29.11%
Fnd. 54.38% 4.58% 29.25%
IR(KBr): 3320 cm"1
'H-NMR (DMSO-d6):7.54 (s, 1H), 7.40 (s, 1H) (H5, H8), 7.04 (s, 1H, pyrazole H4), 2.36
(s, 3H, CH3), 2.33 (s, 3H, CH3)
General Operating Instructions for the Production of 2-Acylhydrazino-3-[3(5)-chloro-1H-
pyrazol-5(3)-yl]-6,7-dimethylquinoxalines of type (G-1)'

A solution of 1.1 equivalents of the corresponding acylating agent - for example acetyl
chloride - in absolute 1,4-dioxane (about 2 ml per mmol of acylating agent) is slowly added in
drops to a suspension that consists of one equivalent of hydrazinoquinoxaline (F-l) and 1.2
equivalents of base (for example, triethylamine, pyridine, and the like) in an absolute solvent (for
example, 1,4-dioxane, THF, acetonitrile) (10 ml per mmol of hydrazino derivative F-l) at room
temperature. After the addition is completed, the reaction batch is stirred at room temperature
until the reaction is completed (about 12-18 hours; TLC monitoring: several drops of the
reaction batch are mixed with water and extracted with ethyl acetate, mobile solvent: for
example ethyl acetate). For working-up, the reaction solution is poured into water, and the
resulting product is then isolated. A possibility of the isolation is the separation of the resulting
precipitate and subsequent washing of the precipitate with water as well as petroleum ether. The

isolation of the product by extraction with a suitable organic solvent represents an alternative; in
this case, the solution of the acylated product is then washed with water and saturated sodium
chloride solution as well as dried, and finally the organic solvent is removed by distillation.
To purify the respective acylated derivative, the corresponding product that is dried until
a constant weight is reached and that consists of a suitable solvent is recrystallized. If necessary,
the crude product is dissolved in advance in a suitable solvent - for example, tetrahydrofuran,
mixed with activated carbon, boiled up, filtered off and evaporated to the dry state in a vacuum.
Synthesis of 2-Acetylhydrazino-3-[3(5)-chloro-1H-pyrazol-5(3)-yl]-6,7-dimethylquinoxaline: (G-
1A)
The production of the compound G-1A is carried out according to the general operating
instructions for the production of compounds of type G-1 with use of the following reaction
parameters or reactants:
Acylating agent: Acetyl chloride
Reaction time: 14 hours
Appearance: Yellow crystals
Yield: 61%
Summation formula: C15H15ClN6O (330.78)
Melting point: 316-320°C (consisting of ethyl acetate-tetrahydrofuran
(1:1))
Elementary analysis: C H N
Cld. 54.47% 4.57% 25.41%
Fnd. 54.39% 4.59% 25.15%
IR(KBr): 3261,1500 cm-1
1H-NMR (DMSO-d6+ D2O): 7.66 (s, 1H), 7.47 (s, 1H) (H5, H8), 7.09 (s, 1H, pyrazole

H4), 2.38 (s, 3H, CH3), 2.37 (s, 3H, CH3), 1.98 (s, 3H, CH3).
General Operating Instructions for Synthesis of 1-Substituted 4-[3(5)-Choloro-1H-pyrazol-
5(3)-yl]-7,8-dimethyl-[1,2,4]triazolo [4,3-a]quinoxalines According to General Formula (1):'

A suspension of acid hydrazide derivative (G-1) in a mixture that consists of 1,2-
dichloroethane (20 ml per mmol) and phosphorus oxychloride (8 ml per mmol) is refluxed until
the reaction is completed (about 2 hours; TLC monitoring: several drops of the reaction batch
are mixed with water and extracted with ethyl acetate, mobile solvent: suitable organic solvent
or organic mixture, for example ethyl acetate).
For working-up, the cooled reaction batch is carefully added to ice water, the resulting
crystalline product is isolated and washed with water as well as petroleum ether. After drying,
the product is dissolved in tetrahydrofuran, mixed with activated carbon, and the mixture is
refluxed for several minutes. The filtrate is evaporated to the dry state in a vacuum, and the
remaining substance is then recrystallized from a suitable solvent.
Synthesis of 4-[3(5)-choloro-1H-pyrazol-5(3)-yl]-1,7,8-trimethyl-[1, 2,4]triazolo[4,3-
a]qninoYaline (I.1.A.):
The synthesis of this compound is carried out by means of previously mentioned, general
operating instructions, whereby the reaction time is two hours.
Appearance: Light yellow powder

Yield: 57%
Summation formula: CisHnClNe (312.76)
Melting point: 278-281 °C (consisting of ethyl acetate)
Elementary analysis: C H N
(relative to Cld. 57.20% 4.36% 25.99%
C15H13ClN6x 0.1 Fnd. 57.00% 4.27% 25.98%
H2O x 0.1 ethyl
acetate)
IR(KBr): 3431cm-1
1H-NMR (DMSO-d6): 14.10 (s, 1H, NH), 8.06 (s, 1H), 7.80 (s, 1H) (H6, H9), 7.54 (s, 1H,
pyrazole H4), 3.11 (s, 3H, CH3), 2.45 (s, 3H, CH3), 2.39 (s, 3H,
CH3).
1.2 Unsymmetrically Substituted Derivatives
Since the reaction of unsymmetrically substituted ortho-phenylenediamines with 3,6-
dihalo-pyridazine-4-carboxylic acid chloride results in general in the formation of an isomer
mixture, and a separation of the isomer compounds is usually associated with a high expenditure
of time and materials, the previously-described process does not allow any especially effective
access to unsymmetrically substituted triazoloquinoxaline derivatives. The alternative synthesis
strategy that is described below makes it possible, however, to obtain isomer-pure products and
thus represents a considerable improvement compared to the current procedure.
This process according to the invention is distinguished in that primarily an iV-acylation
of an ortho-nitroaniline derivative is performed and only in the subsequent step is the second
amino group formed. The latter is carried out by reduction of the nitro group. The additional
reaction steps each correspond to the production of symmetrically substituted derivatives:


[Key:]
Reduktion = Reduction
Hydrazin = Hydrazine
Acylierung = Acylation
Cyclisierung = Cyclization
X and X' are the same radical or a different radical of the above-cited definition with the
limitation X' = halogen, whereby X has the meaning of R6.
R1, R2, R3, and R4 can be defined according to the above-cited descriptions.
The necessary substituted 2-nitroanilines can be purchased, are described in the literature
or are synthetically available analogously to the derivatives that are described in the literature.
Nitration reactions are of special importance here.
In the example of the monomethoxy derivative, this synthesis strategy is described in
more detail below, but the invention is not to be limited to the latter.
Instead of ortho-nitroaniline derivatives, derivatives of substituted
orthophenylenediamines can also be used, if one of the two nitrogen atoms carries a protective

group, and thus it is ensured, on the one hand, that in the acylation only one isomer results, and,
on the other hand, the protective group should be cleavable under extremely mild reaction
conditions. Suitable protective groups are known from the literature; here, for example, N, O-
acetals, N-benzyl, N-benzyloxycarbonyl, N-tert-butyl, N-[di-(p-methoxyphenyl)methyl]-, N-(2,4-
dimethoxybenzyl)-, N-[9-phenylfluoren-9-yl]-, N-silyl derivatives or else imines can be used.
Synthesis of N-(4-Methoxy-2-nitrophenyl)-3,6-dichloro-4-pyridazinecarboxamide (J-1)

5.00 g (32.86 mmol) of 4-methoxy-2-nitroaniline is dissolved in 60 ml of absolute
dichloromethane and mixed with 3.99 g (39.43 mmol, 1.2 equivalents) of triethylamine. After
nitrogen is introduced, 7.30 g (34.51 mmol, 1.05 equivalents) of a solution of 3,6-
dichloropyridazine-4-carboxylic acid chloride is slowly added in drops in several ml of absolute
dichloromethane while being cooled with ice and while being stirred constantly. The reaction
batch is then brought to room temperature, and stirring is continued until the reaction is
completed (about 12 hours; TLC monitoring; mobile solvent: dichloromethane/ethyl acetate =
9/1). For working-up, the reaction mixture is diluted with 50 ml of dichloromethane, and the
organic phase is washed several times with 100 ml each of dilute hydrochloric acid. A portion of
the product accumulates in crystalline form (TLC-pure) in this case and can be filtered off by
suction.
The combined organic phases are washed with water and saturated sodium chloride
solution, dried on anhydrous sodium sulfate, filtered off and evaporated to the dry state in a
Rotavapor. The residue is then recrystallized from ethyl acetate.
Appearance: Almost colorless powder
Yield: 8.36 g (74%)
Melting point: 198-201°C

Summation formula: C12H8Cl2N4O4 (343.13)
IR(KBr): 1720 cm-1
1H-NMR (DMSO-d6): 8.38 (s, 1H, pyridazine H), 7.99 (d, J = 8.8 Hz, 1H, H6),
7.74 (d, J = 2.9 Hz, 1H, H3), 7.51 (dd, J = 8.8 Hz, J = 2.9
Hz, 1H, H5), 3.88 (s, 3H, OCH3)
Reduction of N-(4-Methoxy-2-nitrophenyl)-3,6-dicholoro-4-pyridazinecarboxamide (J-1)

2.000 g (5.83 mmol) of N-(4-methoxy-2-nitrophenyl)-3,6-dichloro-4-
pyridazinecarboxamide (J-1) is dissolved in 50 ml of tetrahydrofuran. 3.676 g (58.29 mmol, 10
equivalents) of ammonium formate and 0.864 g of palladium on activated carbon (10%) are
added to this solution under nitrogen atmosphere, after which the reaction batch is stirred until
the reaction is completed at room temperature (about 18 hours; TLC monitoring; mobile solvent:
dichloromethane/ethyl acetate = 30/1).
For working-up of the reaction batch, the catalyst is filtered off, and the filtrate is
evaporated to the dry state. The residue is mixed with water, and the product is isolated by
exhaustive extraction with ethyl acetate. The collected organic phases are washed with water as
well as saturated sodium chloride solution and dried on sodium sulfate. After the solvent is
distilled off, 1.403 g (77%) of a yellow powder of the composition C12H10CI2N4O2 remains,
which can be further reacted without additional purification.
Melting point: 150-155°C
1H-NMR (DMSO-d6): 9.86 (s, 1H, NH), 8.49 (s, 1H, pyridazine H5), 7.10 (d, J = 8.8 Hz,
1H), 6.34 (d, J = 2.6 Hz, 1H, H3), 6.19 (dd, J = 8.8 Hz, J = 2.6 Hz,
1H, H5), 5.08 (s, 2H, NH2), 3.69 (s, 3H, OCH3)


A solution of 0.695 g (2.22 mmol) of N-(2-amino-4-methoxyphenyl)-3,6-dichloro-4-
pyridazine-carboxamide (C-2) in 25 ml of absolute N,N-dimethylfonnamide is mixed under
nitrogen atmosphere with 0.266 g (6.66 mmol, 3 equivalents) of sodium hydride. The reaction
mixture is stirred until the reaction is completed at 100°C (reaction time: about 15 minutes; for
reaction monitoring, several drops of the reaction batch are mixed with dilute hydrochloric acid
and extracted with ethyl acetate, TLC monitoring of the extract mobile solvent: ethyl acetate; the
complete reaction can be detected in addition from the changing of the reaction solution's color
from dark red to brown).
For working-up, the reaction solution is carefully added under nitrogen atmosphere into
75 ml of dilute hydrochloric acid, after which the resulting suspension is allowed to stand for
several hours at 4°C. The crystalline precipitating product is filtered off by suction and washed
with water as well as petroleum ether. The residue that is dried until a constant weight is reached
is dissolved for purification in tetrahydrofuran, the solution is mixed with activated carbon, and
the mixture is briefly refluxed, filtered off and evaporated to the dry state in a Rotavapor. This
product has adequate purity for the additional reaction. The analytically pure substance of the
composition C12H9ClN4O2 (276.68) is obtained by recrystallization as a yellow powder from
ethyl acetate.
Yield: 0.490 g (80%).
Melting point: 328-330°C
Elementary analysis: C H N
(relative to C12H9ClN4O2 Cld. 52.17% 3.46% 19.62%
x 0.1 ethyl acetate) Fnd. 52.47% 3.62% 19.49%
IR(KBr): 3317, 2811, 1663 (C = 0) cm-1

1H-NMR (DMSO-d6): 13.74 (s, 1H, pyrazole NH), 12.71 (s, 1H, quinoxaline NH),
7.33-7.20 (m, 4H, H5, H7, H8, pyrazole-H4), 3.83 (s, 3H,
OCH3)

0.910 g (3.29 mmol) of the corresponding quinoxalin-2-one derivative (D-2) is dissolved
in 15 ml of phosphorus oxychloride while being cooled with ice, and it is mixed with 1.5 ml of
pyridine; the reaction mixture is then refluxed until the reaction is completed (about 3 hours;
TLC monitoring: several drops of the reaction batch are mixed with saturated sodium
bicarbonate solution and extracted with ethyl acetate, mobile solvent: ether). For working-up,
the reaction batch is first cooled to 0°C, then carefully added to water and neutralized with
saturated sodium bicarbonate solution to improve the crystallization. After several hours of
standing at 4°C, the precipitate is separated. The analytically pure compound of composition
C12H8Cl2N4O (295.13) is obtained by recrystallization from ethyl acetate in the form of yellow
needles:



A suspension of 0.670 g (2.27 mmol) of 2-chloro-3-(3-chloro-lif-pyrazol-5-
yl)quinoxaline (E-2) is suspended in 15 ml of hydrazine monohydrate, after which the reaction
mixture is refluxed until the reaction is completed (reaction time: 2 hours, TLC monitoring:
several drops of the reaction batch are mixed with water and extracted with ethyl acetate, mobile
solvent: ether). For working-up, the reaction batch is added to 75 ml of water and allowed to
stand for several hours at about 4°C. The precipitate that is produced is isolated, washed with
water and petroleum ether and then dried in a vacuum until a constant weight is reached. For
purification, the crude product is dissolved in tetrahydrofuran, mixed with activated carbon, and
this mixture is refluxed for several minutes. After the activated carbon is removed, the solvent is
distilled off, the resulting light residue is then suspended in ether, the solid is isolated and
washed with ether. The thus obtained product of composition C12H11ClN6O (290.71) exhibits
adequate purity for the subsequent reaction. For analytical purposes, a recrystallization from
ethyl acetate is carried out, which provides a beige-greenish powder in 60% yield (0.396 g).
Melting point: 219-222°C
Elementary analysis: C H N
(relative to C12H11ClN6O Cld. 49.86 4.12 27.26
x 0.2 ethyl acetate) Fnd. 50.16 4.16 27.01
1H-NMR (DMSO-d6 + D2O): 7.58 (d, J = 9.0 Hz, 1H, H8), 7.28-7.25 (m, 2H, H5,
H7), 7.08 (s, 1H, pyrazole-H4), 3.86 (s, 3H, OCH3)


The synthesis instructions correspond to the general operating instructions for the
production of compounds of type G-l.
The explanation by way of example is carried out on the following synthesis example:

0.240 g (0.63 mmol) of hydrazinoquinoxaline F-2 is suspended in 30 ml of absolute 1,4-
dioxane and mixed with 0.100 g (0.99 mmol, 1.2 equivalents) of triethylamine. Under protective
gas atmosphere, a solution of 0.146 g (0.91 mmol, 1.1 equivalents) of 2-thienylacetyl chloride in
5 ml of absolute 1,4-dioxane is slowly added in drops at room temperature. The reaction solution
is then stirred until the reaction is completed at room temperature (about 14 hours; for reaction
monitoring, several drops of the reaction batch are mixed with dilute hydrochloric acid and
extracted with ethyl acetate, mobile solvent: ethyl acetate). For working-up, the reaction batch is
added to 75 ml of water, and the mixture is mixed with several milliliters of dilute hydrochloric
acid to improve the crystallization.
After several hours of standing at about 4°C, the crystalline product is isolated and
washed with water as well as petroleum ether. For purification, the dried substance is dissolved
in tetrahydrofuran and mixed with activated carbon. This mixture is refluxed briefly, then it is

filtered, and the solvent is removed by means of distillation. The product that is obtained in this
way in 57% yield (yellowish-beige powder) of the composition C18H15ClN6O2S (414.88) exhibits
an adequate purity for additional reaction.

The synthesis corresponds to the operating instructions for cyclization of compounds of
type G-1 and is explained in more detail in the following synthesis example.

0.195 g (0.47 mmol) of acid hydrazide G-2A is refluxed in a mixture that consists of 5 ml
of phosphorus oxychloride and about 15 ml of an inert solvent (e.g., 1,2-dichloroethane or
acetonitrile) until the reaction is completed (about 2 hours; TLC monitoring: several drops of the
reaction batch are mixed with water, the solution is neutralized with saturated sodium
bicarbonate solution and extracted with ethyl acetate, mobile solvent: ethyl acetate).
After cooling, the reaction mixture is carefully added to 100 ml of ice water, the resulting

crystals are isolated, washed with water and petroleum ether and dried. The aqueous filtrate is
extracted three times with 100 ml each of ethyl acetate, the organic phase is washed with dilute
sodium hydroxide solution, water, as well as saturated sodium chloride solution, and it is dried
on sodium sulfate. The residue that remains after the solvent is distilled off is dissolved for
purification in tetrahydrofuran, mixed with activated carbon and heated to boiling for a short
time. The filtrate that is obtained after the activated carbon is removed is evaporated to the dry
state. The crude product that is obtained is purified by means of column chromatography
(stationary phase: silica gel; mobile phase: ethyl acetate) as well as recrystallization from ethyl
acetate.

Depending on the substitution pattern, compounds can be further derivativized with
substituents on the quinoxaline ring. These derivatizations comprise, for example, the processes
that are known to one skilled in the art, such as acylation, alkylation, nitration, reduction,
hydroxylation, ether cleavage, etc.
Unsymmetrically substituted derivatives can, if this substituent or substituents has/have

influence on the acylation position, also be produced, moreover, starting from substituted ortho-
phenylenediamines. The latter is provided, for example, when electron-withdrawing substituents
are present. Starting from 4-nitrophenylenediamine, this variant of the production of
unsymmetrically substituted compounds (for example with X, X' = Cl and R2 = NO2, R1 = R3 =
R4 = H) is to be illustrated below, without, however, thus limiting the invention to this scope.
Additional reaction steps are performed as described above.


[R2 = strong electron-withdrawing substituent, for example NO2]
An analogous procedure can be used when substituents that have an opposite effect, i.e.,
activation of the amino group, are present. Both variants are also successful when using
multiply-substituted phenylenediamines.
Depending on the substitution pattern, additional modifications can be performed later.
Starting from the nitro group, in particular the reduction to the amino group is of special
importance. This function can be further derivatized - e.g., acylated or alkylated; this function
can also be modified via a diazonium salt.
The previously mentioned synthesis system is explained in more detail based on the
following synthesis examples:

The solution of one equivalent of 3,6-dichloro-4-pyridazinecarboxylic acid chloride in
absolute solvent is slowly added in drops to a mixture of equimolar amounts of 4-

nitrophenylenediamine and base (for example, pyridine, triethylamine, Hünig base) in absolute
solvent (e.g., tetrahydrofuran, dichloromethane, 1,4-dioxane, DMF, and the like) under nitrogen
atmosphere and while being cooled with ice. The reaction batch is stirred at room temperature or
elevated temperature, i.e., up to the boiling heat of the solvent that is used, until the reaction is
completed. For acceleration, the reaction batch can also be treated for several minutes in
ultrasound (TLC monitoring: several drops of the reaction batch are mixed with dilute
hydrochloric acid, the solution is neutralized with saturated sodium bicarbonate solution and
extracted with ethyl acetate, mobile solvent: suitable organic solvent, for example ethyl acetate).
Then, the reaction product is isolated, which is carried out by separation of the crystals that are
produced or by extraction with an organic solvent. Pure crystals are obtained by recrystallization.
Appearance: Yellowish-orange crystals
Melting point: 244°C (from 1,4-dioxane)
Yield: 89%
Summation formula: C11H7Cl2N5O3 (328.12)
IR (KBr): 3448; 3259 (NH2); 1673 (C = O)
1H-NMR (DMSO-d6): 10.41 (s (br), 1 H, NH, exchangeable with D2O);
8.53 (s, 1 H, pyridazine-H5); 8.27 (d, J = 2.6 Hz,
1 H, phenyl-H3); 7.94 (dd, J = 9.2 Hz; J = 2.6 Hz,
1 H, phenyl-H5); 6.83 (d, J = 9.2 Hz, 1 H, phenyl-
H6); 6.68 (s, 2H, NH2, exchangeable with D2O)

3 equivalents of base (preferably 60% sodium hydride dispersion) is added to a solution

that consists of one equivalent of N-(2-amino-5-nitrophenyl)-3,6-dichloropyridazine-4-
carboxamide (C-3) in an anhydrous solvent (for example, N,N-dirnethylformarnide) under
nitrogen atmosphere, after which the reaction mixture is stirred until the reaction is completed at
100°C (reaction time: about 15 minutes; for reaction monitoring, several drops of the reaction
batch are mixed with dilute hydrochloric acid and extracted with ethyl acetate; mobile solvent:
ethyl acetate; the completed reaction can be detected in addition from the changing of the
reaction solution's color from dark red to brown).
Appearance: Yellow crystals
Melting point: 340°C
Yield: 84%
Summation formula: C11H6ClN5O3 (291.66)
IR (KBr): 3274 (NH2); 1687 (C = O)
1H-NMR (DMSO-d6): 13.96 (s, 1H,NH); 13.02 (s, 1H,NH); 8.11-7.93 (m, 3H,
phenyl-H); 7.28 (s, 1H, pyrazole-CH)
The additional reaction to the compound of general formula (I) is carried out with the
formation of the compounds of general formulas (E), (F) and (G) as intermediate products, which
can also be produced just like the already described compounds (E-1), (F-1) and (G-1).
IL Process for the Production of Compounds of Type (1) While Varying Substituent R:
IL1 Derivatives with Different Substituents in 1-Position
Synthesis strategy that is described above and that can be performed analogously to the
prior art can be used for the production of the compounds according to the invention with
different substituents in 1-position (for R ≠ H). Depending on the substitution pattern, further
derivatizations, such as the processes of oxidation, reduction, ether cleavage, acylation,
alkylation, hydrolysis, etc., that are known to one skilled in the art can be performed. The

production of the compounds according to the invention with different substituents in 1-position
is explained based on the examples below, but it is not limited to these examples.
Representatives that carry an alkyl, cycloalkyl, aryl or heteroaryl substituent are presented here,
whereby this radical is connected directly or via a spacer to the tricyclic compound.




























II 2. Derivatives of the Compounds According to General Formula (I) with Hydrogen Atoms
in 1-Position:
Derivatives in which substituent R (1-position) represents a hydrogen atom cannot be
obtained according to the previously-described methods. The latter are reacted, for example, by
reaction of the corresponding hydrazino compound with trimethyl orthoformate. Below, general
operating instructions, which explain the formation of such derivatives, as well as three
examples, are cited.

General Operating Instructions:
A suspension that consists of 2.0 mmol of the corresponding hydrazino compound in
trimethyl orthoformate (about 10 ml per mmol) is refluxed until the reaction is completed (TLC
monitoring: several drops of the reaction batch are mixed with water, the product is extracted
with ethyl acetate, mobile solvent: ethyl acetate).
After cooling to room temperature, the reaction product is isolated. This is carried out
either by the crystallized product being filtered off by suction or by mixing the reaction batch
with water and extraction with a suitable organic solvent (for example, dichloromethane). The
isolated crude product is then purified by recrystallization from a suitable solvent, for example
ethyl acetate, tetrahydrofuran, 1,4-dioxane, N, N-dimethylformamide or alcohols.
II 2. A. Synthesis of 4-[3(5)-Ch1oro-1H-pyrazol-5(3)-yl]-[1,2,4]triazolo[4,3-a]-quinoxaline (a
compound of general formula (T) with R = R1 = R2 = R3 = R4 = H, X =
Reaction time: 2 hours
Yield: 80% (colorless needles)
Summation formula: C12H7ClN6 (270.68)

Melting point: 302-304°C (from THF + 5% DMF)
1H-NMR (DMSO-d6): 14.24 (s, 1H, pyrazole NH), 10.21 (s, 1H, H1), 8.49-8.44
(m, 1H), 8.14-8.08 (m, 1H), 7.88-7.70 (m, 2H) (H6, H7,
H8, H9)
II.2.B Synthesis of 4-[3(5)-Chloro-1H-pyrazol-5(3)-yl]-7,8-dimethyl-[ 1,2,4]triazolo[4,3-a]-
qninoxaline (A Compound nf General Formula (1) with R = R1 = R4 = H, R2 = R3 = CH3, X =
Cl)
Reaction Time: 40 minutes
Yield: 90% (colorless powder)
Summation formula: C14H11ClN6 (298.74)
Melting point: 320-323°C (from THF)
1H-NMR (DMSO-d6): 14.13 (s, 1H, pyrazole NH), 10.04 (s, 1H 1H), 7.75 (s, 1H) (H6, H9), 7.56 (s, 1H, pyrazole-H4), 2.41
(s, 3H, CH3), 2.38 (s, 3H, CH3)
II.2.C. Synthesis of 4-[3(5)-chloro-1H-pyrazol-5(3)-yl]-7-methoxy-[1,2,4]triazolo[4,3-a]-
quinoxaline (A Compound of General Formula (1) with R = R1, R2, R4 = H, R3 = OCH3, X =
Cl)
Reaction time: 4 hours
Yield: 67% (yellowish powder)
Summation formula: C13H9ClN6O (300.71)
Melting point: 287-290°C (starting from 200°C conversion into another
modification) (from ethyl acetate/THF)
1H-NMR (DMSO-d6): 14.21 (s, 1H, pyrazole NH), 10.14 (s, 1H, H1), 8.40 (d, J =
9.0 Hz, 1H, H9), 7.64 (s, 1H, pyrazole-H4), 7.55 (d, J = 2.9
Hz, 1H, H6), 7.47 (dd, J = 9.0 Hz, J = 2.9 Hz, 1H, H8),

3.94 (s, 3H, OCH3)
II .3 Tetrazoloquinoxalines of General Formula (2). (1-Aza Derivatives):
In addition, the invention relates to new tetrazoloquinoxalines that can be considered as
N-isoteres of the previously cited triazoloquinoxalines according to general formula (I), i.e., a
ring-carbon was replaced by nitrogen. Such derivatives are, as indicated based on an example,
accessible by reaction with sodium azide starting from the corresponding chloroquinoxaline
derivatives.

General Operating Instructions:
Equimolar amounts of corresponding chloroquinoxaline derivative and sodium azide are
stirred in absolute N,N-dimethylformamide (about 10 ml per mmol of chlorine compound) at
130°C until the reaction is completed. For working-up, the reaction batch is added to dilute
hydrochloric acid (about 100 ml per mmol, the crystalline accumulating reaction product is
isolated, washed with water as well as petroleum ether and dried until a constant weight is
reached.
Analytically pure product is obtained by recrystallization from a suitable solvent.
II 3 A Synthesis of 4-[3(5)-Chloro-1H-pyrazol-5(3)-yl]tetrazolo[1,5-a]quinoxaline (A
Compound of General Formula (9) with R1 = R2 = R3 = R4 = H, X = Cl)
Reaction time: 5 hours
Yield: 86% (light yellow crystals)
Summation formula: C11H6ClN7 (271.67)

Melting point: 257-258°C (from ethyl acetate)
Elementary analysis: C H N
Cld. 48.63% 2.23% 36.09%
Fnd. 48.45% 2.17% 35.98%
1H-NMR (CDCl3): 14.49 (s, 1H, NH), 8.65-8.60 (m, 1H), 8.31-8.27 (m, 1H),
8.06-7.91 (m, 2H) (H6, H7, H8, H9), 7.62 (s, 1H, pyrazole
H4)
The structural modifications that are described in Sections III and IV below can also be
used in the N-isosteres of general formula (2) according to the invention.
ITT. Process for the Production of Compounds of Types (1) and (2) While Varying Substituent
R5:
In addition, the invention relates to new parazolyl-substituted [1,2,4]triazolo[4,3-
a]quinoxalines, or 1-aza-isosteres, which are characterized in that in the pyrazole ring, there is no
longer a free NH function, but rather another substituent, preferably alkyl, allyl, (hetero)aralkyl or
acyl, carries one of the two nitrogen atoms. The introduction of this substituent R5 is carried out
preferably by subsequent derivatization, for example alkylation, of a compound of general
formula (1), in which R5 is equal to hydrogen:

Owing to the chemical nature of the pyrazole, the formation of the R5-position isomers
can be expected, by which by selection of the suitable reaction conditions, one of the R5-position


isomers should preferably be produced. Optionally-occurring product mixtures can be separated
by purification processes that are known to one skilled in the art, such as fractionated
crystallization or chromatographic separating processes into the isomer-pure R5-substitution
products of general formula (I), as shown above.
Based on some examples, this structural variation is shown, whereby the invention is not
to be limited to this example, however; other operating methods that are described for alkylating
reactions can also be used.
General Operating Instructions for Alkylation of N-Unsubstitnted Derivatives of General
Formula (I)
2 equivalent bases (e.g., powdered potassium hydroxide, sodium, sodium hydride,
potassium-tert-butanolate) are added to a solution of one equivalent of the corresponding N-
unsubstituted derivative of general formula (I) in about 5 ml/mmol of an absolute solvent (for
example, dimethyl sulfoxide, tetrahydrofuran, 1,4-dioxane, DMF) under nitrogen atmosphere,
after which the mixture is stirred for one hour at room temperature. Then, 2 equivalents of the
alkylating agent (preferably alkyl halide or mesylate) are added, after which the reaction mixture
is stirred until the reaction is completed at room temperature (TLC monitoring: several drops of
the reaction batch are mixed with dilute hydrochloric acid and extracted with ethyl acetate,
mobile solvent: for example, dichloromethane/ethyl acetate = 19/1). For working-up, the
reaction batch is added in dilute hydrochloric acid (about 100 ml/mmol). The precipitate that is
produced is filtered off by suction and washed with water as well as petroleum ether or extracted
by extraction with an organic solvent. The dried crude product is then pre-purified by treatment
with activated carbon. A subsequent purification/separation of the positional isomers is carried
out by chromatography, optionally also by fractionated crystallization.
The structures of these derivatives can be determined unambiguously, for example by
means of x-ray structural analysis.
With use of these general operating instructions, the following synthesis examples are

performed for the production of compounds of general formula (I):

Solvent: Absolute dimethyl sulfoxide
Base: Powdered potassium hydroxide
Reaction time: 1.5 hours
Appearance: Yellow, platy-rhombic crystals
Summation formula: C18H13ClN6S (380.86)
Melting point: 205-207°C (from ethyl acetate)
1H-NMR (CDCl3): 8.32-8.27 (m, 1H), 8.06-8.01 (m, 1H), 7.66-7.50 (m, 2H) (H6, H7,
H8, H9), 7.87 (s, 1H, pyrazole H4), 7.24-7.22 (m, 1H), 6.95-6.90
(m, 1H), 6.81-6.80 (m, 1H) (thiophene H3, H4, H5), 5.11 (s, 2H,
CH2), 4.08 (s, 3H, CH3)
Synthesis of 4-[3(5)-Chloro-1 -methyl-1H-pyrazol-5(3)-yl]-1 -(3-phenylpropyl)-
[1,2,4]triazolo[4,3-a]-qninoxaline as Well as Separation into Its Positional Isomers
Solvent: Absolute THF
Base: Powdered potassium hydroxide
Isomer separation: Column chromatography:
Stationary phase: silica gel
Mobile phase: 1,4-dioxane + diisopropyl ether =1 + 1)


Appearance: Colorless crystals
Purification: Recrystallization from EA
Summation formula: C22H19ClN6
(402.86)
Yield: 0.145 g (32%)
Melting point: 179-180°C
IR[cm-1]: 3432, 3158, 2953 (NH)
1H-NMR (CDCl3): 8.29 (d, J = 7.6 Hz, 1H), 7.86-7.80 (m, 1H), 7.65-7.48 (m, 2H))
(H6, H7, H8, H9), 7.86 (s, 1H, pyrazole-H), 7.38-7.20 (m, 5H,
phenyl-H), 4.07 (s, 3H, CH3), 3.50 (t, J = 7.5 Hz, 2H, CH2), 2.93 (t,
J = 7.0 Hz, 2H, CH2), 2.48-2.33 (m, 2H, CH2)

Appearance: Colorless crystals
Purification: Recrystallization from EA
Summation formula: C22H19ClN6 (402.86)
Yield: 0.260 g (58%)
Melting point: 158-160°C
IR[cm-1]: 3432 (NH)
1H-NMR (CDCl3): 8.12 (dd, J = 8.1 Hz, J = 1.5 Hz, 1H), 7.83 (dd, J = 8.1 Hz, J = 1.5

Hz, 1H), 7.69-7.52 (m, 2H) (H6, H7, H8, H9), 7.88 (s, 1H,
pyrazole-H), 7.38-7.21 (m, 5H, phenyl-H), 4.40 (s, 3H, CH3), 3.49
(t, J = 7.6 Hz, 2H, CH2), 2.93 (t, J = 7.2 Hz, 2H, CH2)
A derivatization on the nitrogen atom of the pyrazole ring can take place not only in the
stage of the tri-or tetrazoloquinoxazoline derivative, but also in an earlier reaction stage. For the
compounds in question, the latter can be performed starting from compounds of type (D), (E),
(F) or (G). The subsequent synthesis diagram combines the different possibilities. A process for
introducing an acyl group is described in the literature for (E) with R1 to R4 equal to hydrogen
(B. Matuszczak et al., J. Heterocyclic Chem. 35: 113-115, 1998). Starting from compounds of
type (D), it is preferred to incorporate the derivatization on a compound that has a lactam
protective group on the nitrogen.


[Key:]
Einfuhrung von R5 = Introduction of R5
The introduction of substituents R5, starting from E, is to be described in more detail
below based on an example. The invention in question is not limited thereto., but can optionally
also easily be transferred to other substituents by slight modification of the reaction conditions.
By variation of the conditions, especially by solvent, base, alkylating agent, temperature and
optionally catalyst, the ratio of the two N-isomers can be varied and thus in the individual case
also be shifted in favor of the desired isomer.


[Key:]
(E-Alkyl) als Isomerengemisch = (E-Alkyl) as isomer mixture
TRENNUNG = SEPARATION
Alkylatinn of a 2-Choloro-1-[3(5)-choloro-1H-pyrazol-5(3)-yl]qninoxaline for the Production of
Compounds of the (E-Alkyl) Type:
2 equivalents of a base (for example, powdered potassium hydroxide, sodium, sodium
hydride, potassium-tert-butanolate) and, if necessary, catalytic amounts of an inorganic iodide,
are added to a solution or suspension of one equivalent of a chloroquinoxaline of type (E) in an
inert solvent (for example THF, DMF, 1,4-dioxane, DMSO; in each case preferably absolute
solvent) under nitrogen atmosphere. The mixture is stirred for 1 hour at room temperature.
When a suspension is present, an ultrasound treatment can have an advantageous effect on the
deprotonation and thus on the further course of the reaction. Then, 2 equivalents of the
corresponding alkylating agent, such as alkyl halides or mesylates, are added, after which the
reaction mixture is stirred until the reaction is completed (necessary reaction temperature: room
temperature up to the boiling range of the solvent that is used; the course of the reaction is
tracked by mean of TLC, a sample of the reaction batch is mixed with dilute hydrochloric acid
for this purpose and extracted with ethyl acetate; mobile solvent: suitable solvent or mixture). If
necessary, i.e., in the case of reaction that is incomplete or proceeds too slowly, more base and/or
alkylating agent can be added later. For working-up, the reaction mixture is added to dilute
hydrochloric acid, and the reaction product is isolated. This is carried out by separating the
precipitate that is produced or by extraction with an organic solvent, after which it is then washed
with water. The separation of the isomers as well as their purification is carried out by means of
chromatography and/or recrystallization.
The general operating instructions are explained in more detail based on the following
examples:

A) Synthesis of 2-Chloro-3-[3(5)-choloro-1-ethyl-1H-pyrazol-5(3)-yl]-qninoxaline with R5 =
Ethyl
Base: Powdered potassium hydroxide
Alkylating agent: Ethyl iodide
Solvent: Absolute THF
Isomer separation: Column chromatography:
Stationary phase: silica gel
Mobile phase: dichloromethane + ether = 49 + 1)
Summation formula: C13H10Cl2N4 (293.16)
1st Isomer
Appearance: Colorless crystals
Melting point: 149°C (from diisopropyl ether)
1H-NMR (CDCl3): 8.15-7.84 (m, 4H, H6, H7, H8, H9), 6.78 (s, 1H, pyrazole H4),
4.32 (q, J = 7.2 Hz, 2H, CH2), 1.49 (t, J = 7.2 Hz, 3H, CH3)
2nd Isomer
Appearance: Yellow, platy-rhombic crystals
Melting point: 126°C (from diisopropyl ether)
1H-NMR (CDCl3): 8.23-8.18 (m, 1H), 8.06-8.01 (m, 1H), 7.82-7.76 (m, 2H) (H6, H7,
H8, H9), 7.04 (s, 1H, pyrazole H4), 4.38 (q, J = 7.2 Hz, 2H, CH2),
1.54(t,J = 7.2Hz, 3H,CH3)
B) Synthesis of 2-Chloro-3-[3(5)-chloro-1-(2-methoxyethyl)-1H-pyrazol-5(3)-yl]-quinoxaline
with R5 = methoxyethyl
Base: Powdered potassium hydroxide
Alkylating agent: Methanesulfonic acid-(2-methoxyethyl)ester

Catalyst: Potassium iodide
Solvent: Absolute 1,4-dioxane
Isomer separation: Column chromatography:
Stationary phase: Silica gel
Mobile phase: Dichloromethane + diisopropyl ether =
1 + 1)
Summation formula: C14H12Cl2N4O (323.18)
1st Isomer
Appearance: Colorless crystals
Melting point: 89-90°C
1H-NMR (CDCl3): 8.16-8.02 (m, 2H), 7.91-7.79 (m, 2H) (H6, H7, H8, H9), 6.75 (s,
1H, pyrazole H4), 4.53 (t, J = 5.5 Hz, 2H, CH2), 3.65 (t, J = 5.5 Hz,
2H,CH2), 3.12 (s, 3H,CH3)
2nd Isomer:
Appearance: Colorless needles
Melting point: 125°C
1H-NMR (CDCl3): 8.22-8.16 (m, 1H), 8.06-8.01 (m, 1H), 7.83-7.74 (m, 2H) (H6, H7,
H8, H9), 7.04 (s, 1H, pyrazole H4), 4.48 (t, J = 5.8 Hz, 2H, CH2),
3.88 (t, J = 5.8 Hz, 2H, CH2), 3.76 (s, 3H, CH3)
Production of Compounds of Type I,:
For reaction, a suspension of the corresponding isomer-pure substituted 2-
chloroquinoxaline (E-alkyl) in hydrazine hydrate (about 10 ml/mmol) is refluxed until the
reaction is completed, whereby optionally several ml of a high-boiling solvent, such as, for
example, 1,4-dioxane, is added (reaction monitoring: a sample of the reaction batch is extracted

with ethyl acetate and monitored with TLC, mobile solvent: suitable solvent or mixture). For
working-up, the reaction mixture is added to ice water, and the reaction product is isolated by
separation of the precipitate that is produced or by extraction with an organic solvent, and it is
washed with water. Analytically pure products are obtained from a suitable solvent by
recrystallization. If necessary, the crude product is purified by chromatography in advance.
These general operating instructions are explained in more detail based on the following
synthesis example:
Synthesis of 3-[3(5)-Chloro-1-ethyl-1H-pyrazolo-5(3)-yl]-2-hydrazinoquinoxaline
Summation formula: C13H13ClN6 (288.74)
1st Isomer:
Appearance: Yellowish crystals
Yield: 83%
Melting point: 141-143°C
1H-NMR (CDCl3): 7.96-7.91 (m, 1H), 7.83-7.79 (m, 1H), 7.72-7.64 (m, 1H), 7.54-
7.45 (m, 1H) (H6, H7, H8, H9), 6.62 (s, 1H, pyirazole H4), 4.33 (q,
J = 7.2 Hz, 2H, CH2), 4.18 (s br, 2H, NH2), 1.47 (t, J = 7.2 Hz, 3H,
CH3)
2nd Isomer:
Appearance: Yellowish crystals
Yield: 96%
Melting point: 202-204°C
1H-NMR (CDCl3): 9.29 (s, 1H, NH), 7.92-7.87 (m, 1H), 7.75-7.70 (m, 1H), 7.61-7.53
(m, 1H), 7.53-7.35 (m, 1H) (H6, H7, H8, H9), 7.17 (s, 1H,
pyrazole H4), 4.34-4.23 (m, 4H, NH2, CH2), 1.52 (t, J = 7.2 Hz,

3H, CH3)
Production of Compounds of Type M and Type N:
I) Production of Derivatives with Hydrogen Atom in 1-Position by Reaction of the
Compounds of Type L with Orthoformate
The production is carried out by reaction of the isomer-pure hydrazine of type L
according to general operating instructions (see Section II.2). In this connection, the following
synthesis examples are indicated:
Synthesis of 4-[3(5)-Chloro-1-ethyl-1H-pyrazol-5(3)-yl]-[1,2,4]triazolo[4,3-a]-quinoxaline
Summation formula: C14H11ClN6 (298.74)
1st Isomer:
Appearance: Colorless crystals
Melting point: 282-284°C (from THF)
1H-NMR (CDCl3): 9.36 (s, 1H, CH), 8.19-8.14 (m, 1H), 8.01-7.97 (m, 2H), 7.82-7.69
(m, 2H) (H6, H7, H8, H9, pyrazole H4), 4.32 (q, J = 7.2 Hz, 2H,
CH2), 1.49 (t, J = 7.2 Hz, 3H, CH3)
2nd Isomer:
Appearance: Colorless crystals
Melting point: 191-192°C (from ethyl acetate)
1H-NMR (CDCl3): 9.36 (s, 1H, CH), 8.37-8.31 (m, 1H), 7.99-7.93 (m, 1H), 7.75-7.65
(m, 2H), (H6, H7, H8, H9), 7.88 (s, 1H, pyrazole H4), 4.46 (q, J =
7.3 Hz, 2H, CH2), 1.57 (t, J = 7.3 Hz, 3H, CH3)
II) Reaction of the Compounds of Type L with Acid Chlorides
Starting from compounds of type L, substituted [1,2,4]triazolo[4,3-a]quinoxalines can be

produced according to the methods already previously described, i.e., acylation and subsequent
cyclization (see production of compounds of type G-l and type (1)).
The production is carried out by reaction of the isomer-pure hydrazine of type L
according to general operating instructions (see Section II.2) or by a single-pot process, i.e., the
hydrazide is not isolated, but rather also converted directly into the tricyclic compound.
Although this process is described only on this spot, it is also suitable for the production of
pyrazolyl-unsubstituted derivatives. In this connection see, for example, the following:
Synthesis of 4-[1(5)-Choploro-1-ethyl-1H-pyrazol-5(3)-yl]-1-(3-phenylpropyl)-[1,2,4]triazolo[4,3-
a]-quinoxalinei
Summation formula: C23H21ClN6 (416.92)
1st Isomer:
Production in a Single-Pot Process with Use of Acetonitrile as a Solvent
Appearance: Colorless crystals
Melting point: 175-176°C (from ethyl acetate)
1H-NMR(CDCl3): 8.13-8.08 (m, 1H), 7.89 (s, 1H), 7.86-7.81 (m, 1H), 7.69-7.53 (m,
2H), (H6, H7, H8, H9, pyrazole H4), 7.38-7.21 (m, 5H, phenyl-H),
4.85 (q, J = 7.2 Hz, 2H, CH2), 3.49 (t, J = 7.8 Hz, 2H, CH2), 2.94
(t, J = 7.1 Hz, 2H, CH2), 2.48-2.33 (m, 2H, CH2), 1.55 (t, J = 7.2
Hz, 3H, CH3)
2nd Isomer:
Production in 2 Stages, Namely Acylation and Cyclization with Use of Acetonitrile as a Solvent
Appearance: Colorless needles
Melting point: 146-147°C (from diisopropyl ether)
1H-NMR (CDCl3): 8.33-8.29 (m, 1H), 7.86-7.180 (nm, 2H), 7.66-7.48 (m, 2H)) (H6,

H7, H8, H9, pyrazole H4), 7.38-7.20 (m, 5H, phenyl-H), 4.44 (q, J
- 7.3 Hz, 2H, cH2), 3.50 (t, J = 7.7 Hz, 2H, CH2), 2.94 (t, J = 7.1
Hz, 2H, CH2), 2.48-2.34 (m, 2H, CH2), 1.55 (t, J = 7.3 Hz, 3H,
CH3)

The invention relates to additional pyrazolyl-substituted [1,2,4]triazolo[4,3-a]quinoxaline
or tetrazolo derivatives, in which the chlorine atom that is bonded to the pyrazole ring is replaced
by other halogens or by hydrogen. The dehalogenation can be carried out, for example,
reductively, i.e., by reaction in hydrogen atmosphere or with a hydrogen deliverer such as
ammonium formate in the presence of a suitable catalyst (for example, palladium on activated
carbon (B. Matuszczak, K. Mereiter, 'Synthesis in the Series of Pyrazolyl-Suhstituted
Quinoxalines,' Heterocycles, 45, 2449-2462 (1997)). This dehalogenation reaction is enhanced
by reaction at elevated temperature: As solvents, primarily alcohols, tetrahydrofuran as well as
1,4-dioxane are suitable.

The compounds in their salts, in particular for pharmaceutical use, optionally can be
converted into their physiologically compatible salts with an inorganic or organic acid. As an
acid, for example, succinic acid, hydrogen bromide, acetic acid, fumaric acid, maleic acid,
methanesulfonic acid, lactic acid, phosphoric acid, hydrochloric acid, sulfuric acid, tartaric acid
or citric acid is considered for this purpose. Also, mixtures of the previously mentioned acids
can be used.

If an acid function is present in the molecule, this compound can also be converted into a
physiologically compatible salt for pharmaceutical use. The counterions can have both an
inorganic and an organic nature. In this case, ions consist of alkali metals, alkaline-earth metals,
ammonium as well as ammonium derivatives, in which instead of hydrogen, one to four organic
substituents, preferably alkyl radicals, are present.
In addition, the compounds can also be present in the form of physiologically compatible
solvates, especially hydrates.
In the section below, several results of the biological testing of selected representatives
are listed. The compound number corresponds to the number that is described in the synthetic
portion.

The data of the biological tests that are cited below results from radio ligand-binding
assays on A1, A2A, A2B and A3 adenosine receptors (ARs).
The following selective radioligands are used in the biological tests:
[3H]CCPA (for A1 ARs) [Klotz et al, Naunyn-Schmiedeberg's Arch. Pharmacol,
340, 679 (1989)]
[3H]MSX-2 (for A2A ARs) [Müller et al., Eur. J. Pharm. ScL, 10, 259 (2000)]
[3H]ZM241385 (for A2B ARs_ [X.-D. Ji, K. A. Jacobson, Drug Des. Discov., 16, 217
(1999)]
[3H]PSB-11 (new antagonistic radioligand for human A3 ARs) [M. Dieckmann, M.
Thorand, V. Ozola, C. E. Muller, in Vorbereitung [Preparation] (2001)].
[125I]AB-MECA (for rat-A3 ARs) [Olah et al., Mol. Pharmacol, 45, 978 (1994)].

Description of the Assays That are Used for Testing Substances
Production of Tissue Preparations Made from Rat Brains
For the preparations, deep-frozen rat brains of the Pel Freez Company (Rogers, Arkansas,
USA) are used. The rat brains are thawed in 0.32 M saccharose solution, the cortex is cut off,
and the striata are prepared outside.
The cell decomposing of the cerebral cortex is carried out with a glass-Teflon
homogenizer (stages 5-6, 10 seconds) in 0.32 M saccharose solution. The membranes are
purified over various centrifuging steps. With centrifuging at 600 g, 4°C, for 10 minutes, a large
amount of cell debris is separated via the P1 fraction, and the supernatant (P2 fraction) is further
worked up: in the subsequent three centrifuging steps (35,000 g; 4°C; 60 minutes), a pellet is
produced that is resuspended in 50 mmol of TRIS buffer, pH 7.4 with the Ultraturrax (stages 3-4,
3 seconds); the respective supernatant is discarded. The striata are added to cold TRIS buffer,
homogenized with the Ultraturrax in stages 3 to 4 (3 seconds) and then centrifuged at 35,000 g,
4°C, for 20 minutes. The supernatant is discarded, and the pellet is resuspended in 50 mmol of
TRIS buffer (50 mmol, pH 7.4). The washing process is repeated twice more. The membrane
preparations are stored at -80°C and are held for several months. The cerebral cortex membrane
preparation is used for A1-radioligand binding studies, and the striatum is used for A2A-
radiologiand binding studies.
Tell Culture-
As cell cultures, for example, CHO cells, which express the human Ai-adenosine
receptor, are used.

The nutrient medium, trypsine and PBS (phosphate-buffered common salt solution) are
heated in a water bath to 37°C. The medium is suctioned off from the flask that is approximately
80% to 90% confluently covered with CHO cells. PBS buffer is added, and the latter is allowed
to act for about 5 minutes. Then, the buffer is suctioned off, and the cells are covered with
trypsine/EDTA solution. After about 5 minutes, the cells are detached from the bottom of the
flask. The trypsine/EDTA solution is diluted with at least the same amount of medium. With
this mixture, the flask bottoms are rinsed two to three times to detach cells that are still adhering.
Then, the suspension is added to a centrifuge glass and centrifuged at 20°C for 5 minutes
at 1,000 g. The supernatant is suctioned off, and the cell pellet is taken up in fresh medium. The
cell suspension is dispersed uniformly into 20 to 25 cell culture flasks that are inscribed with 20
to 25 and that are filled with medium. The flasks are lightly shaken to disperse the cells well and
then incubated for 2 to 3 days in an incubator (37°C; 5% CO2).
The following medium composition is used, for example, for CHO cells:
DMEM F12 with the following additives:
• 10% fetal calf serum
• 1% penicillin/streptomycin (finished mixture with 10,000 U of penicillin and 10
mg of streptomycin)
• 2 mmol of L-glutamine (stock solution: 200 mmol in 0.85% NaCl solution)
• 0.2 mg/ml of G418 (genticin sulfate)
For CHO cells that express the A2A-adenosine receptor, the operating steps are performed
analogously to the previously mentioned A1-adenosine receptor-CHO culture. 0.5 U/ml of
adenosine deaminase is added to the medium.
In addition, A28-adenosine receptor membranes are prepared, whereby, for example,
finished prepared membranes of HEK cells, which express the human A2B-receptor in high

density (about 4 pmol/mg of protein), were available commercially (Receptor Biology USA via
Perkin Elmer Life Sciences, Cologne, Germany).
For CHO cells, which express the A3-adenosine receptor, the operating steps are also
performed analogously to the A1-adenosine receptor-CHO culture. The medium is used as
described above.
Membrane Preparation of Recombinant Human Receptors:
Preparation of recombinant, human Ai-adenosine receptors expressed by CHO cells for
Ai-adenosine receptor binding studies:
2 to 3 ml of ice-cold TRIS buffer (pH 7.4; 50 mmol) is added to the small tissue culture
dishes. The cells are scraped off from the plates with a rubber scraper and collected in a beaker.
The plates are rinsed with another 1 to 2 ml of TRIS buffer (pH 7.4; 50 mmol) and added to a
beaker. The cell suspension is dispersed onto centrifuge tubes, homogenized with the
homogenizer at the highest level (3 to 4 seconds) and centrifuged at 4°C, 35,000 g, for 20
minutes. The supernatant is discarded, and the pellet is resuspended in TRIS buffer (pH 7.4; 50
mmol) with the glass-Teflon homogenizer at the highest level for 3 to 4 seconds. This
suspension is centrifuged again (4°C; 35,000 g, 20 minutes). The washing process is repeated
another time. The pellet that is obtained is resuspended with the least possible TRIS buffer (pH
7.4; 50 mmol) and delivered in aliquots (0.25 ml and 0.5 ml).
Preparation of recombinant human A2A-adenosine receptors expressed in CHO cells for
A2A-adenosine receptor binding studies:
2 to 3 ml of ice-cold TRIS buffer (pH 7.4; 50 mmol) is added to the tissue culture dishes.
The cells are scraped off from the plates with a rubber scraper and collected in a beaker. The
plates are rinsed with another 1 to 2 ml of TRIS buffer (pH 7.4; 50 mmol). The cell suspension

is dispersed to the centrifuge tubes and centrifiiged at 4°C, 35,000 g, for 20 minutes. The
supernatant is discarded, and the pellet is resuspended in TRIS buffer (pH 7.4; 50 mmol) with the
homogenizer at the highest level for 3 to 4 seconds. This suspension is again centrifuged. The
washing process is repeated still another time. The pellet that is obtained is resuspended with the
least possible TRIS buffer (pH 7.4; 50 mmol) and delivered in aliquots (0.25 ml and 0.5 ml).
Before the tissue is used in an assay, it must again be washed with TRIS buffer (pH 7.4;
50 mmol) for 20 minutes at 4°C and 35,000 g. The unspecific binding can thus be reduced.
Preparation of Recombinant Human A3-Adenosine Receptors Expressed in CHO Cells for A3-
Adenosine Receptor Binding Studies
2 to 3 ml of ice-cold TRIS buffer (pH 7.4; 50 mmol) is added to the tissue culture dishes.
The cells are scraped off from the plates with a rubber scraper and collected in a beaker. The
plates are rinsed with another 1 to 2 ml of TRIS buffer (pH 7.4; 50 mmol). The cell suspension
is dispersed into centrifuge tubes and centrifuged at 4°C, 35,000 g, for 20 minutes. The
supernatant is discarded, and the pellet is resuspended in TRIS buffer (pH 7.4; 50 mmol) with the
homogenizer at the highest level for 3 to 4 seconds. This suspension is again centrifuged. The
washing process is repeated another time. The pellet that is obtained is resuspended with the
least possible TRIS buffer (pH 7.4; 50 mmol) and delivered in aliquots (0.25 ml and 0.5 ml).
Radioligand-Receptor Rinding Studies:
The test substances are dissolved in DMSO to 10 mmol. The final concentration of
DMSO in the assay is 2.5% for A1- and A2A-adenosine receptor assays and 1-2% for A2B- and
A3-assays. Dilution series of the test substances are produced from the stock solution. Five to
eight different test concentrations, which comprise 3 orders of magnitude (e.g., 1 nm to 1000

nm), are used.
Radioligand Binding Studies with [3H]CCPA on A1-Adenosine Receptors:
Contained in 1 ml of total volume are 25 ul of DMSO (total bond) or 25 ul of 2-
chloroadenosine (400 µmol in DMSO, unspecific bond) or 25 ul of test substance in DMSO as
well as 775 µl of TRIS buffer, 50 mmol, pH 7.4; 100 µl of [3 H]CCPA (final concentration: 0.5
nmol; KD-value: 0.2 nmol) and 100 ul of rat brain homogenate (70 ug/ml) or a membrane
preparation that consists of CHO cells, which express recombinant human A1-adenosine
receptors (30-50 g/ml) in 50 mmol of TRIS buffer, pH 7.4, mixed with 0.12 I.U. ADA. The
mixture is incubated for 90 minutes in an oscillating water bath at 23°C. Then, it is filtered off
with a Brandel cell-harvester and washed twice more with ice-cooled TRIS buffer, 50 mmol, pH
7.4 (3 ml). The filter plates are conveyed in scintillation vials, doused with 2.5 ml of Ultima
Gold Scintillation cocktail and incubated for at least 6 hours before they are measured in a
scintillation counter.
Receptor Binding Assay with [3H]MSX-2 on A2A-Adenosine Receptors:
25 µl of DMSO, NECA (800 nmol) or test substance dilutions
775 µl of TRIS buffer (for production, see above)
100 µl of [3H]MSX-2 (final concentration 1 nmol; KD value 8 nmol)
100 µl of rat-striatum-membrane preparation or preparation of CHO cells, which
express the human A2A receptor, incubated with 0.12 IE adenosine-deaminase
(protein concentration: 25-75 µg/ml)
1000 µl of final volume


The assay is performed according to the instructions of the receptor-binding assay with
[3H]CCPA with consideration of the amounts and solutions that are listed above. The incubation
time is 30 minutes at 23°C in an oscillating water bath. The glass fiber filter is introduced 30
minutes before use in 0.5% PE1 solution.
Receptor Binding Assay with [3H]ZM241385 Expressed on Recombinant A2B-Adenosine
Receptors in HEK Cells:
10 µl of DMSO, NECA (1 mmol) or test substance dilutions
790 µl of 10 mmol HEPES buffer, pH 7.4 (for production, see above)
100 µl of [3H]ZM241385 (final concentration 5 nmol; KD-value 33 nmol)
100 µl of membrane preparation, incubated for at least 15 minutes with 0.12 IE
adenosine-deaminase (protein concentration: 40 µg/ml)
1000 µl of final volume
The membranes are thawed and the receptor-binding assays are carried out with
[3 H]CPPA according to the instructions given below with consideration for the amounts and
solutions listed above. The dilution in the assay is 1:100 (to reduce the DMSO content to 1 %,
since a higher DMSO concentration has a disadvantageous effect). The incubation time is 30
minutes at 23°C in an oscillating water bath. The glass filter is introduced into 0.5% PEI solution
30 minutes before use.
Receptor Binding Assay with [3H]PSB-11 on Recombinant A3-Adenosine Receptors Expressed
in CHO Cells:
10µl of DMSO, R-PIA (100 µmol) or test-substance dilutions


350 µl of 50 mmol of TRIS buffer, pH 7.4 (for production, see above)
40 µl of [3H]PSB-11 (final concentration 0.5 nmol; KD-value 2 nmol)
100 µl of membrane preparation (at least 15 minutes) incubated with 0.12 of IE
adenosine deaminase (protein concentration: 100 µg/ml)
500 µl of final volume
The assay is performed with [3H]CCPA according to the instructions under the receptor-
binding assays with consideration for the above-listed amounts and solutions. The dilution in the
assay is 1:50. The DMSO content is 2% here. The incubation at 23°C in the oscillating water
bath lasts for 45 minutes.
[35 S]GTP γ Assay:
10 µl of DMSO, GTPyS or test-substance dilutions
150 µl of TRIS buffer, 50 mmol, pH 7.4 for [35S]GTPγS assay (see above)
20 µl of [35S]GTPγS (final concentration 0.1 to 0.5 nmol; corresponds to ~ 1250
Ci/mmol)
20 µl of membrane preparation, incubated with 0.12 IE adenosine-deaminase (protein
concentration: 75 µg/ml)
200 µl of final volume

First, solutions of the test substances in DMSO are produced in the required
concentrations. The curve consists of 7 to 8 measuring points (measured in each case as triplets),
which extend over a concentration range of 6 to 7 powers often. After the addition of 50 mmol
of TRIS buffer, 50 mmol, pH 7.4, to the radioligand [35S]GTPγS and the membrane preparation,
which was mixed with adenosine deaminase, a final volume of 200 µl is achieved. The
incubation is carried out for 45 minutes at 25°C in an oscillating water bath. Then, the reaction is
first stopped with 2 ml of cold washing buffer (50 mmol of TRIS, 5 mmol of MgCl2 x 2 H2O, pH
7.4), and the suspension is filtered with a GF/B filter with the aid of the harvester. The reagent
glasses are rinsed twice with 2 ml each of column washing buffer. The filter plates are conveyed
by means of a punched-out plate into the scintillation vial, which is filled with 2 ml of
Scintillation cocktail. The vials are shaken well to wet the filter papers completely. After an
incubation of at least 3 hours, the radioactivity in the LS counter is determined by a 2-minute
measurement. The curves are reproduced three times in each case.
In the assay, solutions of test substances 1:20 are diluted; the DMSO content in the assay
is 5% (V/V).
Evaluation of the Radioligand Rinding Studies:
The mean value is calculated from three independent experiments. IC50 and K1 values are
obtained from the Cheng-Prusoff equation, the concentration and the KD value of the radioligand.
For calculation, the program GraphPadPrism™, Version 3.0 (GraphPad, San Diego, California,
USA), was used.






Table 2. Receptor Affinities of Several New Triazolo- and Tetrazoloquinoxaline Derivatives
(nt = not tested)
Dosages and Forms nf Administration
The compounds of general formula (1) or (2) according to the invention can be
administered to patients perorally, for example by means of tablets, coated tablets, capsules and
drinking solutions; rectally, for example by means of suppositories; by inhalation, for example by

inhaling aerosols at defined concentration and size distribution of particles; transdermally, for
example by active ingredient-containing patches, rubbing solutions, gels, etc.; transmucosally, for
example in terms of a resorption through the mucous membranes of the mouth and nose,
whereby the active ingredient in the cavity of the mouth is released by solution in the saliva, or
can be introduced into the nose by spray solutions and the like, by means of implanted
condensers, which, for example, release the active ingredient by passive osmosis or in a
controlled manner by means of mini-pumps or the like; or by an intravenous, intramuscular or
subcutaneous injection and intracerebroventricular method.
Typical dosages in the administration of these active ingredients depend on the type of
compound that is used and lie in a range of 0.5-100 mg (preferably 1-50 mg) for intravenous
administration for an average adult; in the range of 1-1000 mg (preferably 5-500 mg) for peroral
administration, and in the range of 0.5-50 mg (preferably 1-20 mg) for transdermal
administration.
Owing to the variable administration spectrum, the compounds of general formulas (1) or
(2) according to the invention are suitable for the production of pharmaceutical agents for
treating diseases in the kidney area, such as in acute renal failure, nephritis, hepatorenal
syndrome; for treating the heart, preferably for treating cardiac irregularities, ischemia,
myocardial infarction or angina pectoris; for treating the central nervous system (CNS);
preferably for treating dementia, Alzheimer's disease, anxiety disorders, epilepsy, Parkinson's
disease, stroke, depression, opiate withdrawal or comatose conditions; or for treating the lungs,
preferably for treating respiratory diseases, such as asthma, bronchitis and mueoviscidosis; and
for treating hypertension, allergic skin diseases, such as urticaria, or inflammations.
In addition, immunostimulants as well as protective agents, which are used in lung
transplants, can be produced from compound (1) or (2) according to the invention.

WE CLAIM:
1. Pyrazolyl-substituted [1,2,4-]triazolo[4,3-a]quinoxalines according to formula (1)

in which R1 to R4 are hydrogen, directly or via oxygen or via carbonyl(oxy) bonded C1 to C8
hydrocarbon radicals which are unbranched, branched, linear or cyclic, saturated or partially
unsaturated with double and/or triple bond(s) optionally having one or more heteroatoms, namely O,
S or N, aryl or heteroaryl radicals, in the form of a mono-, bi- tri and tetracyclic ringsystem of from 5
to 9 ring atoms having up to four hetero atoms per ring independently selected from N, O or S,
alkoxy, hydroxy, halogen, amino, nitro, trihalomethyl, carboxy, alkoxycarbonyl or sulfo groups,
whereby Rl to R4 are identical or different or can be present as fused aryl or heteroaryl radicals in
the form of a mono-, bi- tri and tetracyclic ringsystem of from 5 to 9 ring atoms having up to four
hetero atoms per ring independently selected from N, O or S, or as correspondingly hydrogenated or
partially hydrogenated systems, and in which substituent R is hydrogen or a linear or branched-chain,
saturated, and/or unsaturated C1 to C6 hydrocarbon radical, a C3 to C8 cycloalkyl radical, an aryl or
heteroaryl radical in the form of a mono-, bi- tri and tetracyclic ringsystem of from 5 to 9 ring atoms
having up to four hetero atoms per ring independently selected from N, O or S, in substituted or
unsubstituted form, whereby substituent R is bonded to the base either directly or via an alkylene
group, in which one or more carbon atoms can be replaced by heteroatoms, such as oxygen, sulfur or
nitrogen, and in which substituent R5 is hydrogen, C1-C8 alkyl, allyl, arylalkyl, (hetero) arylalkyl or
acyl, and in which radical R6 is a halogen or hydrogen, excluding compounds with R1 to R5 equal
to hydrogen, R6 equal to chlorine and R equal to methyl, phenyl, benzyl, 2-furyl, 2-thienyl or 2-
thienylmethyl.
2. Process for the production of pyrazolyl-[1,2,4]triazolo[4,3-a]quinoxalines according to
formula (1), comprising the steps of:

reacting substituted 1,2 diazines according to formula (C)

in which radicals R1, R2, R3, and R4 have the meaning according to claim 1 and in which X' is a
leaving group, such as herein described, and X is halogen or hydrogen, by ring closure in the manner
such as herein described, to form pyrazolyl-substituted quinoxalines according to Formula (D)

followed by production of 2-chloroquinoxaline derivatives according to formula (E), in the manner
such as herein described,
reacting the said derivatives of formula (E), in the manner such as herein described, to the
corresponding 2-hydrazino derivatives according to formula (F)

obtaining the compounds according to Formula (G)


from the derivatives of formula (F), by acylation,
and obtaining from the compounds of formula (G), by ring closure reaction in the manner such as
herein described, the pyrazolyl[l,2,4]triazolo-[4,3-a]quinoxalines according to formula (1).
3. Process as claimed in claim 2, wherein the ring closure reaction is carried out by starting
from the corresponding hydrazine without isolating the hydrazide intermediate product.
4. Process as claimed in claim 2 or 3, wherein the compounds according to formula (G) are
obtained from substituted 2-chloroquinoxalines by reaction with hydrazides.
5. Process as claimed in any one of claims 2 to 4 for production of symmetrically
substituted pyrazolyl[1,2,4]triazolo[4,3-a]quinoxalines, wherein substituted diazine according to
formula (C) is obtained by reaction of o-phenylenediamine
according to formula (B),

in which radicals R1 to R4 have the meaning as defined in claim 1, with activated 3,6-
dihalopyridazine-4-carboxylic acid.
6. Process as claimed in claim 2, for the production of unsymmetrically substituted pyrazolyl
[1,2,4]triazolo[4,3-a]-quinoxalines according to formula (1), as defined in claim 1, wherein
substituted diazines according to formula (C), are obtained by N-acylation of the o-nitroaniline
derivatives according to formula (H)


with 3,6-dihalopyridazine-4-carboxylic acid chloride, with formation of the compound according to
formula (J)

in which the amine group in the compound according to formula (C) is obtained by reduction of the
nitro group.
7. Process for the production of unsymmetrically substituted tricyclic compounds according
to formula (1), as defined in claim 1, wherein an unsymmetrically substituted phenylenediamine is
used with one or more substituents that influence the reactivity, so that at least one of the two amino
groups for an acylation reaction is activated or deactivated, by which a selective substitution is
carried out on the ring system/on the ring systems.
8. Pyrazolyl-substituted tetrazolo[1,5-a]quinoxalines according to formula (2),


in which R1 to R6 as well as R have the meanings as defined in claim 1.
9. Process for the production of compounds according to general formula (1) or (2)

in which R1, R2, R3, R4 and R6 are as defined in claim 1, with R5 being unequal to hydrogen, as
well as the separation of the accumulating isomers, wherein either a compound of formula (1) or (2)
with R5 equal to hydrogen is alkylated or wherein the introduction of substiruent R5 already takes
place in the steps of obtaining compounds (D), (E), (F) or (G), as claimed in claim 2, where the
reaction of 2-chloroquinoxaline (E) being preferred.
10. Process for the production of the compound according to formula (2), defined in claim 9,
wherein the compound of formula (E), as defined in claim 2, is produced and reacted with salts of
hydrazoic acid.
11. Pyrazolyl[1,2,4]triazolo[4,3-a]quinoxalines according to formula (1), as defined in claim
1, or pyrazolyl-substituted tetrazolo[1,5-a]quinoxalines according to formula (2), as defined in claim
8, that are isolated or in the form of their pharmaceutically compatible salts and solvates as
pharmaceutical active ingredients, in particular as adenosine receptor ligands.
12. Pharmaceutical agent, wherein as active ingredient, it contains pyrazolyl-substituted
[1,2,4]triazolo[4,3-a]quinoxalines according to formula (1), as defined in claim 1, and/or pyrazolyl-
substituted tetrazolo[1,5-a]quinoxalines according to formula (2), as defined in claim 8, and/or their
pharmaceutically compatible salts.

13. Pharmaceutical agent as claimed in claim 12, which is present in a form that is suitable
for peroral, rectal, inhalational, transdermal, transmucosal, or intracerebroventricular administration.
14. Pharmaceutical agent as claimed in claim 12, which is present in a form of administration
that is suitable for implants, infusions or injections.
15. Pharmaceutical agents as claimed in any one of claims 12 to 14, which are capable of
being used for treating diseases in the kidney area, such as for acute renal failure, nephritis,
hepatorenal syndrome; for treating the heart, preferably for treating cardiac irregularities, ischemia,
myocardial infarction or angina pectoris; for treating the central nervous system (CNS); preferably
for treating dementia, Alzheimer's disease, anxiety disorders, epilepsy, Parkinson's disease, stroke,
depression, opiate withdrawal or comatose conditions; or for treating the lungs, preferably for
treating respiratory diseases, such as asthma, bronchitis and mucoviscidosis.
16. Pharmaceutical agents as claimed in any one of claims 12 to 14, which are capable of
being used as protective agents, in lung transplants.

17. Pharmaceutical agents as claimed in any one of claims 12 to 14, which are capable of
being used for treating hypertension, allergic skin diseases, such as urticaria, or inflammations.
18. Pharmaceutical agent as claimed in any one of claims 12 to 14, which is capable of being
used as an immunostimulant.

According to the invention, derivatives of pyrazolyl[1,2,4]triazolo[4,3-
a]quinoxaline according to formula I or the analog in the form of pyrazolyl-substituted
tetrazolo[1,5-α]quinoxalines according to formula II are indicated. The substances according to
formula 1 or 2 are suitable in this form or in the form of their pharmaceutically compatible salts
as active ingredients, in particular as adenosine receptor ligands.

Documents:

838-kolnp-2004-granted-abstract.pdf

838-kolnp-2004-granted-assignment.pdf

838-kolnp-2004-granted-claims.pdf

838-kolnp-2004-granted-correspondence.pdf

838-kolnp-2004-granted-description (complete).pdf

838-kolnp-2004-granted-examination report.pdf

838-kolnp-2004-granted-form 1.pdf

838-kolnp-2004-granted-form 18.pdf

838-kolnp-2004-granted-form 3.pdf

838-kolnp-2004-granted-form 5.pdf

838-kolnp-2004-granted-gpa.pdf

838-kolnp-2004-granted-reply to examination report.pdf

838-kolnp-2004-granted-specification.pdf


Patent Number 226497
Indian Patent Application Number 838/KOLNP/2004
PG Journal Number 51/2008
Publication Date 19-Dec-2008
Grant Date 17-Dec-2008
Date of Filing 17-Jun-2004
Name of Patentee JSW-RESEARCH FORSCHUNGSLABOR GMBH
Applicant Address RANKENGASSE 28, A-8020, GRAZ
Inventors:
# Inventor's Name Inventor's Address
1 MATUSZCZAK BARBARA HERZOG-FRIEDRICH-STRASSE 11 A-6020, INNSBRUCK
2 MULLER CHRISTA E ALFRED-BUCHERER-STRASSE 9, 53115 BONN
PCT International Classification Number C07D 487/04
PCT International Application Number PCT/AT02/00361
PCT International Filing date 2002-12-19
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 A 2025/2001 2001-12-21 Austria