Title of Invention

PROCESS FOR THE RECYCLING OF SOLID PHASE BONDED CTC-RESIN

Abstract

The present invention relates to a recycling process for the preparation of solid phase bonded 2-chlorotrityl chloride (2-CTC resin) useful for solid phase peptide synthesis. Specifically what is claimed is a process for the preparation of solid phase bonded 2-chlorotrityl chloride (2-CTC resin) of formula I5 wherein-Ps is a polymeric support and n has the following meaning; 1 >= n> 0 comprising the reaction of solid phase bonded 2-chlorotrityl of formula II, wherein R is OH or/and OCl-4-alkyl or/and NR'R" wherein R* and R" independently of each other represent Cl-4-alkyl, or R' and R" together with the nitrogen to which they are bonded represent a 5 to 8 membered heterocyclic radical in the presence of a chlorinating agent and an organic solvent.

Full Text

Process for the recycling of solid phase bonded ctc-resin Trityl resins are useful solid phase bonded protecting groups, originally developed for solid phase peptide synthesis and as well used for solid phase organic synthesis. Solid phase bonded 2-chlorotrityl chloride (2-CTC resin) is commercial available [CBL Patras] and based on crosslinked polystyrene (Ps) or modified polystyrenes (e.g. teritagel, polystyrene grafted with polyethylerieglycol) [1: catalog ACTj NoviabiocherhJ: The 2- CTC linker is an nr\c\ lahilp resin artrl Keranse of its excellence bronerties nlavinS a significant role in hoVel iMer techhbld^ [2:THI; 1997,6347,2629; Int. J. Pep. Pfbt. Res. 37 Yl 9911 513L tteavaeebf bebtides from 2-CTC re:sih can be effected bv treatment under very mild acidic conditions (e. g. dilute TFA/DCM, AcOH/DCM, HFIP) [1,3: Liebigs A. 1988,1079, THL 1997,72$?], Despite being an expensive [1] and a valuable synthetic tool, a si^iplg, efficient, gentle, reproducible experimental description for the recycling of-in solid phase synthesis - "used 2-CTC resin" without any loss of activity is so far unknown in the Hterature. To syhtJiesize 2-CTC resin from the 2ichIorbtriphehylcarbihdl resin (2-CT-OH resin), references are giveii to the experimental pitocfedure of the parent tritylchlpride re^in frbrri the: tripHfe^lniethkriolresin iriah arialogoiis mariner [4: THIi 1989* 3943; 1 bail! j:Cl^54v(|^ detailed [1, 5: THI? 199^3241; 6: Reactl Fimcfc Polym.41 (1999) 111]. WO 01/85758 A2 [7] discloses the recycling of carboxylic acid (e.g. preferably trifluoroacedic acid) trityl ester resins with HC1 in CH2CI2- Apart of the fact that trifluoroacedic acid trityl esters are subject to hydrolysis [8: ZVPhy. Chem. 113 (1978) 199] and therefore difficult to hancUe, the reexamination of the example given in [7] achieved only 77% of the content of active chloride [6] before use. After loading of 2-CTG resin with Fmoc-amino acids, unreacted active sites are end-capped with alcohols, especially methanol and Fmoc protecting groups are deprptected with ^roine^ 9; W-CvChan, p. D, White in Fmoc Solid Phase Peptide Synthesis] leading to 3 certain amount of methylether and amine substructures in .the resin. These substructures decrease, the yield of the recycling step and consequently the activity (content of active chloride) of the recycled resin. Surprisingly it has now been found, that by carryiiig out a reaction of used 2-CTC resin (comprising of a compound of formula II) ixi the presence'bf a chlorinating agent and an organic solvent, the recovered 2-CTC resin achieved unexpectedly the Content of active chloride [6] before use. Further it has been found that above recycling of "Used resin" surprisingly took place quantitatiydy due to conversion of compound of formula II wherein R is, as defined below tq 2rCTC resin. The recycled 2-CTC resin loaded successftU Fmoe-Trp(Boc) or Fmoc-Leu [9:,p. 217]. -Itjvas found that chlorination with ; HCHb the presence of an, prganic $olyentis aisp; applicable for; the conversion of 2-CT-OH resin to 2-GTC resin. The present invention describes a process for the preparation of solid phase bonded 2-chlofbtrityl chloride (2-CTC resin) of formula I wherein Vsis a polymeric support ana n nas me xoiiowing meaning; i ^ us u comprising the reaction of sblid pMSe bonded 2-chlorotrityl of formula II wherein R is OH or/and OCM-alkyl or/and NR'R" wherein R' and R" independently of each other represent CM-alkyl, or R' and R" together with the nitrogen to which they are bonded represent a 5 to 8 membered heterocyclic radical in the presence of a chlorinating agent and an organic solvent In a further embodiment the reaction is carried out wherein R is OH, OCH3, OQH5, OC3H7, and R' and R" independently of each other represent methyl, ethyl, or R' and_R" together ™\th tVip nitrogen to which th^v arp hnnded represent piperidine most preferred wfterein R is OH or/and OCH3 or/and piperidine iri the presence of HCland an organic solvent.; The teim "polymeric support" within the present invention means polymeric resins suitable for use in solid phase synthesis, or surfaces in \yhich polymers, having synthesis properties similar to these polymeric resins are attached to a solid support, or modified silica gels suitable for use in solid phase synthesis, preferably polystyrene (0-25% divinylbenzene crosslinked), more preferred 0-10% divinylbenzene crosslinked and most preferred 1% divinylbenzene crosslinked. The term "solid phase bonded 2-chlorotrityl" within the present invention means 2-chlorotrityl bonded to the polymeric support as defined above. The value "n" within the present invention has the following meaning: 1 > n> 0, therefore the value "n" may be between 0 and 1, whereas 1 is included. In a preferred embodiment, the value "n" has the following meaning: 0.9 > n > 0.5. The term "alky!" as used herein denotes an optionally substituted straight or branched chain hydrocarbon residue containing 1 to 4 carbon atoms; such as methyl, ethyl, n-propyl, isopropyl, n-butyl, l-sec-butyl> isobutyl and tert-butyl. Preferably, the term "alkyl" denotes an optionally substituted straight or branched chain hydrocarbon residue containing 1 to 3 carbon atoms. More preferred the term "alkyl" denotes a methyl or ethyl group. Most preferred the term "alkyl" denotes a methyl group. Within the present invention a compound of formula II wherein R is OH or/and OCi-4-alkyl or/and NR'R" wherein R* and R" independently of each other represent Ci-4-alkyl, or R' and R" together with the nitrogen to which they are bonded represent a 5 to 8 membered heterocyclic radical (preferably wherein R is OH, OCH3) OC2H5) OC3H7> dimethylamine, diethylamine, methylethylamine or/and piperidine; most preferred wherein R is OH or/and OCH3 or/and piperidine) is used. The ratio of OH and OCM-alkyl and NR'R" may be between 100:0:0 and 0:100:0 and 0:0:100. In a preferred embodiment the compound of formula II wherein R is OH is enriched. Within the present invention 5 to 8 membered heterocyclic radicals for the term NR'R" are the following moieties: pyrrolidinyl> piperidinyl According to the present invention, "used resin" (formula II), obtained after peptide cleavage [1,3], e.g. in the c^se ofT-20 or T-1249 (10: US 5,464,933, US 6258782] and quenching with pyridine (traces of water) [11: JAGS 80 (1958) 812], was recycled after washing (e.g. dioxane) in the presence of a chlorinating agent and an organic solvent. The carbinol substructure in "used resin" could be verified by IR-spectroscopy (VOH = 3566 cm"1)! Trace amounts of Methanol (evidence of minimum -OCH3 content in "used resin") could be detected by GC in the filtrate of the recycling experiments and nitrogen content by elemental analysis of "used 'resin".Thfe recycling reaction maybe carried out in organic solvents: e. g. toluene, chlorobenzene, CH2CI2, DMSO, NMP (1-metyl-2-pyrroiidinone), DM?, ethers or cyclic ethers with high absorption capacity of HC1 gas (such as alkylethers, DME, Diglyrne, THF of dioxane). The recycling reaction is preferably carried out in the presence of THF or dioxarie, most preferred in the presence . of dioxane. Further, the recycling reaction may be carried but with chlorinating agents known from textbooks about organic chemistry (e.g. from J. March (1992), "Advanced Organic Chemistry: Reactions, Mechanisms, and Structure", 4th ed. John Wiley &c Sons) such as PCU, PCI3, POCl3, SOCl2, CH3COCl, CO2CI2, (CH3)3SiCI or HCL Preferred chlorinating agents are PC15, PC13> POCl3 or HC1, and most preferred chlorinating agent is HCl. In a further embodiment, the present invention may be carried out in a single percolation or in repetitive percolations. In a preferred embodiment, the process is carried out with excess HC1. The reaction may be carried out at a temperature between 0°C and 110°C preferably at a temperature between 0-50°C and most preferred at a temperature between 10°Cand25°C The reaction may be carried out in the organic solvent (preferred dioxane or THF, most preferred dioxane) wherein the HC1 content is about 10-20 g/100 ml, most preferred > 20 g/100 ml. In a further embodiment of the invention, the reaction maybe carried out in the organic solvent (preferred dioxane or THF, most preferred dioxane) wherein the HC1 content is > 0 to about 40 g/lOOml, preferably 10-35 g/lQO ml, and most preferred 20-30 g/100 ml. The reaction maybe c—'~J ~"*c— ^ n^ u ^^^fQ^oKKr fnr 17.QA h anH most preferred for 21-24 h. Experimental part: In a double-walled jacket reactor with glass frit bottom 5 g pure "used resin" ..(formula II) was.- optionally after pretreatment in the organic solvent (table 1) and suction of the solvent - stirred slowly in the organic solvent (table 1) with /dissolved! chlorinating agent (table l)at specified reaction temperature (T: table 1) for specified reaction tirhe (t: table 1). After completion of the percolation and suction of the reaction solution the remaining resin was washed with the reaction solvent, treated with hexane and dried under vacuum at 35°C. The content of active chloride (table 1) of the recycled 2-CTC resin (formula I) was determined [6] and its content of nitrogen by elemental analysis was below detection limit. The virgin 2-CTC resin (formula I) had content of active chloride before use: -1.27 mol/kg. The "used resiii" (formula II) had no active chloride before use [6] and the content of compound of formula II wherein R is OC1-4-alkyl is lower 5% but higher 0%, and the content of nitrogen is lower 0.2% but higher From the data presented in Table 1 it is clear, that by carrying out the reaction according to the present invention the recovered 2-CTG resin achieved unexpectedly the content of active chloride before use. Claims 1. Process for the preparation of solid phase bonded 2-chlorotrityl chloride (2-CTC resin) of formula I wherein Ps is a polymeric support and n has the following meaning: 1 > n> 0 comprising the reaction of solid phase bonded 2-chlorotrityl of formula II wherein R is OH or/and OQ,4-alkyl or/and NR'R" wherein R' and R" independently of each other represent Ci^-alkyl, or R* and R" together with the nitrogen to which they are bonded represent a 5 to 8 membered heterocyclic radical in the presence of a chlorinating agent and an organic solvent. 2. Process according to claim 1 wherein the organic solvent is toluene, chlorobenzene, CH2C12> DMSO, NMP> DMF, alkylethers, DME, Diglyme, THF or dioxane. 3. Process according to claim 1 or 2 wherein the chlorinating agent is PCI5, PCI3, POCl3) SOCI2, CHaCOCl, C02C12) (CH3)3SiCl or HCL 4. Process according to claims 1-3 wherein n has the following meaning: 0.9 > n > 0.5. 5. Process according to claim 1-4 wherein the reaction temperature is between 0 and 110°C. 6. Process according to claim 1-5 wherein the HC1 content in dioxane is > 0 to about 40 g/lOOml, 7. Process according to claim 1-6 wherein the reaction time is 6-96 h. 8. Process according to claim 1-7 wherein it is carried out in a single percolation or in repetitive percolations

Documents:

1325-chenp-2005-abstract.pdf

1325-chenp-2005-claims.pdf

1325-chenp-2005-correspondnece-others.pdf

1325-chenp-2005-correspondnece-po.pdf

1325-chenp-2005-description(complete).pdf

1325-chenp-2005-form 1.pdf

1325-chenp-2005-form 18.pdf

1325-chenp-2005-form 3.pdf

1325-chenp-2005-form 5.pdf

1325-chenp-2005-pct.pdf