Title of Invention

2,4,5-SUBSTITUTED THIAZOLE DERIVATIVES AS CANNABINOID RECEPTOR MODULATORS

Abstract

The present invention relates to a group of thiazole derivatives, to methods for the preparation of these compounds, to pharmaceutical compositions containing at least one these compounds as active ingredient, as well to the use of these compositions for the treatment of psychiatric and neurological disorders and other diseases involving cannabinoid CB neurotransmission. 'The thiazole derivatives of the invention are either cannabinoid (CB) receptor antagonists, CB receptor antagonists, CB receptor inverse agonists or CB receptor partial agonists The compounds have the general formula (1) wherein R, R<SUB>l</SUB> and X have the meanings given in the specification.

Full Text

THIAZOLE DERIVATIVES AS CANNABINOID RECEPTOR MODULATORS The present invention relates to a group of thiazole derivatives, to methods for the preparation of these compounds, to pharmaceutical compositions containing at least one these compounds as active ingredient, as well to the use of these compositions for the treatment of psychiatric and neurological disorders and other diseases involving cannabinoid CB neurotransrnission. The thiazole derivatives of the invention are either cannabinoid (CB) receptor antagonists, CB receptor agonists, CB receptor inverse agonists or CB receptor partial agonists. The thiazole derivatives of the invention bind either on the CB1 receptor or on the CB2 receptor or on both the CB1 and CB2 receptor. The invention relates to the use of a compound disclosed herein for the manufacture of a medicament giving a beneficial effect. A beneficial effect is disclosed herein or apparent to a person skilled in the art from the specification and general knowledge in the art. The invention also relates to the use of a compound of the invention for the manufacture of a medicament for treating or preventing a disease or condition. More particularly, the invention relates to a new use for the treatment of a disease or condition disclosed herein or apparent to a person skilled in the art from the specification and general knowledge in the art. In embodiments of the invention specific compounds disclosed herein are used for the manufacture of a medicament. Thiazoles have been claimed in WO0127094 as triglyceride inhibitors. WO0426863 describes thiazole derivatives as transforming growth factor (TgF) inhibitors. 4,5-Diarylthiazole derivatives have been described in EP 388909 and EP 377457 as 5-lipoxygenase inhibitors for the treatment of thrombosis, hypertension, allergy and inflammation. The exemplified structures therein all contain two phenyl rings which are p-substituted with a methoxy, fluoro, methylthio or methylsulfinyl group. WO 9603392 describes sulfonylaryl-arylthiazoles for inflammation and pain, arthritis or fever as inflammation-associated disorders. JP 05345772 relates to 4,5-diarylthiazoles as acetyl cholinesterase inhibitors, and JP 04154773 describes 4,5-diaryithiazoles having analgesic, anti-inflammatory and antipyretic action. t has now surprisingly been found that the thiazole derivatives of the formula (I), pro-jrugs thereof and salts thereof vherein - R and R1 are the same or different and represent phenyl or pyridinyl, optionally substituted with 1-3 substituents Y, wherein Y represents a substituent from the group methyl, ethyl, propyl, methoxy, ethoxy, hydroxy, hydroxymethyl, hydroxyethyl, chloro, iodo, bromo, fluoro, trifluoromethyl, trifiuoromethoxy, methylsulfonyl, methylsulfanyl, trifluoromethylsulfonyl, phenyl or cyano, with the proviso that X does not represent the subgroup (ii), or one of the moieties R and R1 represents a phenyl or pyridinyl group, optionally substituted with 1-3 substituents Y, wherein Y has the abovementioned meaning and the other moiety represents a hydrogen atom or a C1-8 branched or linear alkyl group, C3-8 branched or linear heteroalkyl group containing one heteroatom from the group (N, 0, S), a C3.7 cycloalkyl group, C3-7-cycloalkyl-C1-3-alkyI group, C3-7-rheterocycloalkyl-C1-3-alkyI group which groups may be substituted with a hydroxy, methoxy, methyl, trifluoromethylsulfonyl or trifluoromethyl group or a fluoro atom and which C3-7-heterocycloalkyI-C1-3-alkyl group contains one or two heteroatoms from the group (0, N, S), or said other moiety represents a benzyl group optionally substituted on its phenyl ring with 1-3 substituents Y, wherein Y has the abovementioned meaning, X represents one of the subgroups (i) or (ii), wherein - R2 represents a d-s branched or linear alkyl group, C3-7 cycloalkyl group, cycloalkyi-C-1-2-aIkyl group, Cs-r-heterocydoalkyl-C1-2-alkyl group which groups may be substituted with a hydroxy, methyl or trifluoromethyl group or a fluoro atom and which C3-7-heterocycloaIkyI-C1-2-alkyl group contains one or two heteroatoms from the group (O, N, S), or R2 represents a phenyl, benzyl, phenethyl or phenylpropylgroup which may be substituted on their phenyl ring with with 1-3 substituente Y, wherein Y has the abovementioned meaning, or R2 represents a pyridyl, thienyl or naphtyl group, which napthyl group may be substituted with a halogen atom, a methyl group or a methoxy or trifluoromethyl group,, - R3 represents a hydrogen atom or a branched or linear C1-3 alkyl group, - R4 represents hydrogen, a branched or linear d-10 alkyl or C3-8-cycloalkyI-C1-2- alkyl group, branched or linear C1-10 alkoxy, C3-8 cycloalkyl, C5-10 bicycloalkyl, C5- io-bicycloalkyl-C1-2-alkyl, C6-10 tricycloalkyl, C6-IO tricycloalkyl-methyl, branched or linear C3-1O alkenyl,C5-8 cycloalkenyl, which groups may contain one or more heteroatoms from the group (O, N, S) and which groups may be substituted with a hydroxy group, 1-3 methyl groups, an ethyl group or 1-3 fluoro atoms, or R4 represents a phenyl, phenylamino, phenoxy, benzyl, phenethyl or phenylpropyl group, optionally substituted on their phenyl ring with 1-3 substituents Y, wherein Y has the abovementioned meaning, or R4 represents a pyridyl or thienyl group, or R4 represents a group NR5R6 wherein R5 and RB - together with the nitrogen atom to which they are attached -form a saturated or unsaturated, monocydic or bicyclic, heterocyclic group having 4 to 10 ring atoms, which heterocyclic group contains one or more heteroatoms from the group (O, N, S) and which heterocyclic group may be substituted with a branched or linear d-3 alkyl, phenyl, hydroxy or trifluoromethyl group or a fluoro atom, or R3 and FU - together with the nitrogen atom to which they are attached - form a saturated or unsaturated, monocydic or bicyclic, heterocydic group having 4 to 10 ring atoms, which heterocyclic group contains one or more heteroatoms from the group (O, N, S) and which heterocyclic group may be substituted with a branched or linear CV3 alkyl, phenyl, amino, hydroxy, methoxy, cyano or trifluoromethyl group or a fluoro or chloro atom, 35 are modulators of the cannabinoid CB receptor. To the invention belong all compounds having formula (I), racemates, mixtures of diastereomers and the individual steroisomers. Thus compounds in which the substltuents on potentially asymmetrical carbon atoms are in either the reconfiguration or the S-configuration belong to the invention. Also prodrugs, i.e. compounds which when administered to humans by any known route, are metabolised to compounds having formula (I), belong to the invention. Prodrugs are bioreversible derivatives of drug molecules used to overcome some barriers to the utility of the parent drug molecule. These barriers include, but are not limited to, solubility, permeability, stability, presystemic metabolism and targeting limitations (J. Stella, Trodrugs as therapeutic”, Expert Opin. Ther. Patents, 14(3), 277-280, 2004). In particular this relates to compounds with primary or secondary amino or hydroxy groups. Such compounds can be reacted with organic acids to yield compounds having formula (I) wherein an additional group is present which is easily removed after administration, for instance, but not limited to amidine, enamine, a Mannich base, a hydroxyl-methylene derivative, an 0-(acyloxymethylene carbamate) derivative, carbamate, ester, amide or enaminone. A pro-drug is an inactive compound, which when absorbed is converted into an active form (Medicinal Chemistry: Principles and Practice, 1994, BBN 0-85186-494-5, Ed.: F. D. King, p. 216). Due to the CB receptor activity the compounds according to the invention are suitable for use in the treatment of psychiatric disorders such as psychosis, anxiety, depression, attention deficits, memory disorders, cognitive disorders, appetite disorders, obesity, addiction, appetence, drug dependence and neurological disorders such as neurodegenerative disorders, dementia, dystonia, muscle spasticity, tremor, epilepsy, multiple sclerosis, traumatic brain injury, stroke, Parkinson's disease, Alzheimer's disease, epilepsy, Huntington's disease, Tourette's syndrome, cerebral ischaemia, cerebral apoplexy, craniocerebral trauma, stroke, spinal cord injury, neuroinflamrnatory disorders, plaque sclerosis, viral encephalitis, demyelinisation related disorders, as well as for the treatment of pain disorders, including neuropathic pain disorders, and other diseases involving cannabinoid neurotransmission, including the treatment of septic shock, glaucoma, cancer, diabetes, emesis, nausea, asthma, respiratory diseases, gastrointestinal disorders, sexual disorders, gastric ulcers, diarrhoea and cardiovascular disorders. PHARMACOLOGICAL METHODS In vitro affinity for human cannabinoid CB1 receptors The affinity of the compounds of the invention for cannabinoid CBn receptors can be determined using membrane preparations of Chinese hamster ovary (CHO) cells in which the human cannabinoid CB1 receptor is stably transfected in conjunction with [3H]CP-55,940 as radioligand. After incubation of a freshly prepared cell membrane preparation with the [3H]-Iigand, with or without addition of compounds of the invention, separation of bound and free ligand is performed by filtration over glassfiber filters. Radioactivity on the filter is measured by liquid scintillation counting. In vitro affinity for human cannabinoid CB2 receptors The affinity of the compounds of the invention for cannabinoid CB2 receptors can be determined using membrane preparations of Chinese hamster ovary (CHO) cells in which the human cannabinoid CB2 receptor is stably transfected in conjunction with [3H]CP-55,940 as radioligand. After incubation of a freshly prepared cell membrane preparation with the [3H]-ligand, with or without addition of compounds of the invention, separation of bound and free ligand is performed by filtration over glassfiber filters. Radioactivity on the filter is measured by liquid scintillation counting. In vitro antagonism on human cannabinoid CB1 receptors In vitro CBi receptor antagonism can be assessed with the human CB1 receptor cloned in Chinese hamster ovary (CHO) cells. CHO cells are grown in a Dulbecco's Modified Eagle's medium (DMEM) culture medium, supplemented with 10% heat-inactivated fetal calf serum. Medium is aspirated and replaced by DMEM, without fetal calf serum, but containing [3HI-arach]donic acid and incubated overnight in a cell culture stove (5% CO2/95% air; 37 QC; water-saturated atmosphere). During this period [3H]-arachidonic acid is incorporated in membrane phospholipids. On the test day, medium is aspirated and cells are washed three times using 0.5 mL DMEM, containing 0.2% bovine serum albumin (BSA). Stimulation of the CB1 receptor by WIN 55,212-2 leads to activation of PLA followed by release of [3H]-arachidonic acid into the medium. This WIN 55,212-2-induced release is concentration-dependently antagonized by CB1 receptor antagonists. The CB1 antagonistic potencies of the test compounds are expressed as pA2 values. In vivo antagonism on human cannabinoid CBn receptors In vivo CB1 antagonism can be assessed with the CP-55,940-induced hypotension test in rat. Male normotensive rats (225-300 g; Harlan, Horst, The Netherlands) are anaesthetized with pentobarbital (80 mg/kg ip). Blood pressure is measured, via a cannula inserted into the left carotid artery, by means of a Spectramed DTX-plus pressure transducer (Spectramed B.V., Bilthoven, The Netherlands). After amplification by a Nihon Kohden Carrier Amplifier (Type AP-621G; Nihon Kohden B,V., Amsterdam, The Netherlands), the blood pressure signal is registered on a personal computer (Compaq Deskpro 386s), by means of a Po-Ne-Mah data-acquisition program (Po-Ne-Mah Inc., Storrs, USA). Heart rate is derived from the pulsatile pressure signal. All compounds are administered orally as a microsuspension in 1% methylcellulose 30 minutes before induction of the anesthesia which is 60 minutes prior to administration of the CB-i receptor agonist CP-55,940. The injection volume is 10 mL kg-1. After haemodynamic stabilization the CB-, receptor agonist CP-55,940 (0.1 mg kg”1 i.v.) is administered and the hypotensive effect established. (Wagner, JA ef a/., Hemodynamic effects of cannabinoids: coronary and cerebral vasodilation mediated by cannabinoid CB1 receptors. Ear. J. PhatrnacoL 2001, 423,203-210). This hypotension test can also be used to assess CB1 receptor agonistic effects of the compounds. Such CBi agonistic effects on blood pressure may be counteracted by a selective CB-, receptor antagonist such as rimonabant. Cannabinoid receptor agonistic or partial agonistic activity of compounds of the invention can be determined according to published methods, such as assessment of in vivo cannabimirnetic effects (Wiley, J. L et a!., J Pharmacol Exp. Ther. 2001, 296, 1013). The compounds of the invention can be brought into forms suitable for administration by means of usual processes using auxiliary substances and/or liquid or solid carrier materials. Compounds of the present invention are generally administered as pharmaceutical compositions which are important and novel embodiments of the invention because of the presence of the compounds, more particularly specific compounds disclosed herein. Types of pharmaceutical compositions that may be used include but are not limited to tablets, chewable tablets, capsules, solutions, parenteral solutions, suppositories, suspensions, and other types disclosed herein or apparent to a person skilled in the art from the specification and general knowledge in the art. In embodiments of the invention, a pharmaceutical pack or kit is provided comprising one or more containers filled with one or more of the ingredients of a pharmaceutical composition of the invention. Associated with such container(s) can be various written materials such as instructions for use, or a notice in the form prescribed by a governmental agency regulating the manufacture, use or sale of Pharmaceuticals products, which notice reflects approval by the agency of manufacture, use, or sale for human or veterinary administration. GENERAL ASPECTS OF SYNTHESES Thiazole derivatives can be obtained according to methods known, for example. a) Organic Reactions, Vol. VI, (1951), p. 367-409, Ed. R. Adams, John Wiley and Sons Inc., New York b) J. S. Carter et al., Bioorg. Med. Chem. Lett. (1999), 9,1167-1170 c) T. T. Sakai et al., Bioorg. Med Chem. (1999), 7,1559-1566 d) A. Tanaka et al., J. Med. Chem. (1994), 37,1189-1199 e) J. J. Talley et al., WO 9603392: Chem. Abstr. 125, 33628 f) V. Cecchetti et al., Bioorg. Med Chem. (1994), 2, 799-806 g) T. Eicher et al., The Chemistry of Heterocycles, (1995) p. 149-155, Georg Thieme Verlag, Stuttgart, 1995, ISBN 313-100511-4, and references cited therein h) Gilchrist, T.L, Heterocyclic Chemistry, 3th Ed. 1997, p. 319-327, Longman, UK, ISBN 0-582-27843-0. Alfahaloketones can be obtained by halogenation of the corresponding ketone. The reaction of affa-halo carbonyl compounds and thioamide can produce a wide range of thiazole derivatives. More in particular, condensation of alfa-bromoketones with ethyl thiooxamate provides (2-ethoxy-carbonyl)thiazoles of general formula (II). Compounds of formula (II) can be converted to the corresponding N-methoxy-N-methylamide (III) and subsequently reacted with an alkyliithium or aryl lithium reagent to give a compound of general formula (1), wherein X represents subgroup (i). Compounds of general formula (II) can be amidated with an amine of general formula R3R4NH into a compound of general formula (I) wherein X represents subgroup (if). Such amidations can be catalyzed by (CH3)3AL (For more information on aluminum-mediated conversion of esters to amides, see: J. I. Levin, E. Turos, S. M. Weinreb, Synth. Commun. (1982), 12, 989-993.) Alternatively, a compound having formula (II) is converted into the corresponding carboxylic acid and subsequently reacted with a so-called halogenating agent such as for example thionyl chloride (SOCI2). This reaction gives the corresponding carbonyl chloride that is subsequently reacted with a compound having formula R3R4NH wherein R3 and R4 have the meanings as described above. Alternatively, the ester group in (II) can be converted to the corresponding carboxylic acid. This carboxylic acid can be reacted with a compound having formula R3R4NH wherein R3 and R4 have the meanings as described hereinabove via activating and coupling methods such as formation of an active ester, or in the presence of a so-called coupling reagent, such as for example, DCC, HBTU, HOAT (N-hydroxy-7-azabenzotriazole), BOP, CIP (2-chloro-1,3-dimethyIimida2olinium hexafluoro-Dhosphate), PyAOP (7-azabenzotriazol-1-yloxytris(pyrroIidino)-phosphonium hexa-luorophosphate) and the like. (For more information on activating and coupling methods see a) M. Bodanszky, A. Bodanszky: The Practice of Peptide Synthesis, Springer-Verlag, New York, 1994; ISBN: 0-387-57505-7; b) K. Akaji et aL, Tetrahedron Lett. (1994), 35, 3315-3318; c) F. Albericio et al., Tetrahedron Lett. 1997), 38,4853-4856). According to these procedures the following compounds can be prepared. They are itended to further illustrate the invention in more detail, and therefore are not deemed to restrict the scope of the invention in any way. SYNTHESES OF SPECIFIC EXAMPLES 1H NMR spectra were recorded on a Varian UN400 instrument (400 MHz) with tetramethylsilane as an internal standard. Chemical shifts are given in ppm (d?scale) downfield from tetramethylsilane. Coupling constants (J) are expressed in Hz. Thin-layer chromatography was performed on Merck pre-coated 60 F254. plates, and spots were visualised with UV light. Flash chromatography was performed using silica gel 60 (0.040-0.063 mm, Merck). Column chromatography was performed using silica gel 60 (0.063-0200 mm, Merck). Melting points were recorded on a Buchi B545 melting point apparatus and are uncorrected. Example 1 Part A: To a solution of 1-(2s4-dichlorophenyI)-2-phenylethanone (54.35 gram, 0.205 mol) in benzene (220 mL) is slowly added bromine (10.6 mL, 0.205 mol) and the resulting solution is stirred at room temperature for i hour. Aqueous (5 %) NaHCO3 solution is slowly added. The organic layer is separated, dried over MgSO4, filtered and evaporated in vacua to give crude 2-bromo-1 -(2,4-clichlorophenyl)-2-phenylethanone (69.4 g, 98 % yield) as an oil. 1H-NMR (400 MHz, CDCt): d 8.20 (s, 1H), 7.26 (del, J = 8 and 2 Hz, 1H), 7.31-7.50 (m, 7H). Part B; 2-Bromo-1-(2,4-dichlorophenyI)-2-phenylethanone (25.83 gram, 0.075 mol) and ethyl thiooxarnate (15.0 gram, 0.112 mol) are dissolved in absolute ethanol (200 mL). The resulting mixture is heated at reflux temperature for 16 hours. After evaporation in vacuo the crude material is dissolved in a mixture of water and dichloromethane. The dichloromethane layer is separated and the water layer is extracted three times with dichloromethane. The collected organic layers are dried (MgSO4), filtered and concentrated. The resulting material is purified by column chromatography (silica gel / dichloromethane) to give ethyl 4-(2,4-dichloropheny!)-5-phenylthiazole-2-carboxylate (10.5 gram, 37 % yield). 1H-NMR (400 MHz, CDCI3): d T.46 (t, J = 7 Hz, 3H), 4.53 (q, J = 7 Hz3 2H)3 7.24-7.38 (m, 7H), 7.43 (d, J = 2 Hz, 1H). Part C: To a solution of ethyl 4(2,4-dichlorophenyI)-5-phenylthiazole-2-carboxylate (10.5 g, 0.028 mol) in methanol (170 ml) is slowly added a solution of KOH (8.9 g, 0.0896 mol) in water (170 ml). The resulting solution is heated at 90 °C for 2 hours and cooled to room temperature. A mixture of concentrated HCI and ice is added. The formed precipitate is collected, washed with water and diethyl ether and dried to give 4-(2,4-dichlorophenyl)-5-phenyIthiazole-2-carboxylic acid (8.99 gram, 92 % yield). Melting point: 105 °C. Example 5: Melting point: 131-132 °C. Example 6 Part A: To a magnetically stirred solution of 1-phenylheptan-1-one (23.7 gram, 0.125 mo!) in benzene (160 mL) is slowly added bromine (7.0 mL, 0.125 mol) and tie resulting solution is reacted at room temperature for 1 hour. Aqueous (5 %) NaHCO3 solution is slowly added, followed by dichloromethane. The organic layer is separated, dried over MgSO4s filtered and evaporated in vacuo to give crude 2 bromo-1-phenylheptan-1-one (41.8 g, quantitative yield) as an oil. 1H-NMR (400 MHz, CDCI3): dtt.90 (t, J = 7 Hz, 3H), 1.28-1.78 (m, 6H), 2.04-2.25 (m, 2H), 5.11- 5.16 (m, 1H), 7.42-7.62 (m, 3H), 8.00-8.04 (m. 2H). Part B; 2-Bromo-1-phenylheptan-1-one (20.17 gram, 0.075 mol) and ethyl thiooxamate (15.0 gram, 0.112 mol) are dissolved in absolute ethanol (200 mL). The resulting mixture is heated at reflux temperature for 16 hours. After evaporation in vacuo the crude material is dissolved in a mixture of water and dichloromethane. The dichloromethane layer is separated and the water layer is extracted three times with dichloromethane. The collected organic layers are dried (MgSO4), filtered and concentrated. The resulting material is purified by column chrornatography (siiica gel / dichloromethane/petroleum ether = 1/1) to give ethyl 5-(n-pentyI)-4-phenylthiazole-2-carboxylate (12.09 gram, 53 % yield) as an oil which slowly solidified. Melting point: 51-52 °C. Part C: To a magnetically stirred solution of ethyl 5(n-pentyI)-4-phenylthiazole-2- carboxylate (12.09 g, 0.039 mol) in methanol (240 ml) is slowly added a solution of KOH (8.9 g) in water (240 ml). The resulting solution is heated at reflux temperature for 2 hours and subsequently cooled to room temperature. A mixture of concentrated HCI and ice is added. The formed precipitate is collected, successively washed with water and cold diethyl ether and dried to give 5-(n-pentyl)-4-phenyithiazole-2- carboxylic acid (3.54 gram, 32 % yield). 1 H-NMR (400 MHz, CDCI3): d?3.87 (t, J = 7 Hz, 3H), 1.28-1.40 (m, 4H), 1.66-1.76 (m, 2H), 2.93-3,00 (m, 2H), 4.00 (br s, 1H), 7,35-7.46 (m, 3H), 7.58-7.64 (m, 2H). Part D: To a magnetically stirred suspension of 5-(n-perrtyI)-4-phenyithiazole-2-carboxylic acid (1.18 g, 0.0043 mol) in anhydrous dichloromethane (35 ml) is successively added 7-aza-1-hydroxybenzotriazoie (HOAT) (1.46 gram, 0.0107 mol), 7-azabenzotriazoI-1-yioxytris(pyrroIidino)phosphonium hexafluorophos- phate (PyAOP) (5.59 gram, 0.0107 mol), diisopropylethyiamine (2.24 ml, 0.0129 mol) and aniline (0.98 ml, 0.0107 mol) and the resulting solution is stirred for 16 hours at room temperature. The resulting mixture is concentrated and purified by flash chromatography (silica gel / dichloromethane) to give N-pheny!-5-(n-pentyl)-4-phenylthiazole-2-carboxamide (0.89 gram, 59 % yield). 1H-NMR (400 MHz, CDCb): d from 5-(n-pentyI)-4-phenylthiazole-2-carboxyIic acid and 1-aminoadamantane. Example 7: Melting point: 90-92 °C. from 5-(n-pentyl)-4-phenytthiazole-2-carboxyIic acid and cis-myrtanylamine (CAS 38235-68-6) Example 9 Part A: 1-Bromo-1-phenylheptan-2-one (19.98 gram, 0.074 mol) and ethyl thiooxamate (15.0 gram, 0.112 mol) are dissolved in absolute ethanol (200 mL). The resulting mixture is heated at reflux temperature for 2 hours. After evaporation in vacuo the crude material is dissolved in a mixture of water and dichloromethane. The dichloromethane layer is separated and the water layer is extracted three times with dichloromethane. The collected organic layers are dried (MgSO4), filtered and concentrated. The resulting material is purified by column chromatography (silica gel Analogously were prepared: Ethyl 4-benzyI-5-phenylthiazole-2-carboxylate as an oil. Ethyl 5(n-pentyl)-4-(2,4-dichoropheny()thia2ole-2-carboxylate. Melting point: 92-93 °C. Part B: To a magnetically stirred solution of 1-aminoadamantane (1.607 gram, 0.0086 mol) in anhydrous dichloromethane (10 ml) is added AI(CH3)3 (4.3 mL, 2M solution in hexane, 0.0086 mol) and the resulting solution is reacted at room temperature for 10 minutes. Aqueous (5 %) NaHCO3 solution is slowly added. Extraction with dichloromethane, drying over MgSO4, filtration and concentration in vacuo, followed by column chromatography (silica gel / dichloromethane) gives N-

Documents:

941-CHENP-2006 ABSTRACT.pdf

941-CHENP-2006 CLAIMS GRANTED.pdf

941-CHENP-2006 CORRESPONDENCE OTHERS.pdf

941-CHENP-2006 CORRESPONDENCE PO.pdf

941-CHENP-2006 FORM 18.pdf

941-CHENP-2006 FORM 2.pdf

941-CHENP-2006 FORM 3.pdf

941-CHENP-2006 PETITIONS.pdf

941-chenp-2006-abstract.pdf

941-chenp-2006-claims.pdf

941-chenp-2006-correspondnece-others.pdf

941-chenp-2006-description(complete).pdf

941-chenp-2006-form 1.pdf

941-chenp-2006-form 3.pdf

941-chenp-2006-form 5.pdf

941-chenp-2006-pct.pdf

941.rtf