Cysteine methyl ester

Almqvist and coworkers have developed a two-step synthesis of optically active 2-pyridones via thiazolines (Scheme 6.216) [388]. Thus, heating a suspension of (R)-cysteine methyl ester hydrochloride with 2 equivalents of an imino ether and 2 equivalents of triethylamine base in 1,2-dichloroethane at 140 °C for 3 min furnished the desired thiazolines in near quantitative yield with limited racemization. Purification by filtration through a short silica gel column and concentration of the filtrate gave a crude product, which was used directly in the next step. Thus, after... 

For the synthesis of a small library of palmitoylated and isoprenylated N-Ras peptides in solution, a modular strategy was adopted, with the tetrapeptide MGLP 38 as a key intermediate. This tetrapeptide allowed further elongation at its C-terminus with lipidated or nonlipidated cysteine methyl esters, as well as the addition of various N-terminally MIC-labeled dipeptides, consisting of different GC lipidated units 39—41... 

S-Farnesylated cysteine methyl ester represents in most of the cases the C-terminal residue of the synthetic model peptides. The choice whether to use this amino acid derivative or related larger fragments for the final coupling step, strongly depends upon the peptide sequence. 

An early synthesis of A5-palmitoy]-.S -[2,3-bis(palmitoyloxy)propyl]cysteine employed cysteine methyl ester, however, this leads to difficulties in the saponification step of the tri-palmitoylated residue. 96 The optimized procedure, in which the cystine di-fert-butyl ester is used, 90 is outlined in Scheme 6 after N-acylation with palmitoyl chloride, the ester is reduced to the cysteine derivative for S-alkylation with l-bromopropane-2,3-diol to yield chirally defined isomers if optically pure bromo derivatives are used. Esterification of the hydroxy groups is best carried out with a 1.25-fold excess of palmitic acid, DCC, and DMAP. The use of a larger excess of palmitoyl chloride is not recommended due to purification problems. The diastereomeric mixture can be separated by silica gel chromatography using CH2Cl2/EtOAc (20 1) as eluent and the configuration was assigned by comparison with an optically pure sample obtained with 2R)- -bromopropane-2,3-diol. 

Acetophenone was enantioselectively hydrosilylated using a catalyst prepared from [(COD)Rh Cl]2 and the (R)-cysteine derivative (27). (27) is the condensation product of (R)-cysteine methyl ester and 2-pyridinecarboxaldehyde. 

Condensation of (R)-cysteine methyl ester (85) with monochloroacetone followed by reduction with sodium borohydride yielded (3R,5S)-5-methyl-l,4-thiazane-3-carboxylate (86a) and its (5R)-methyl isomer (86b) in a ratio of 3.1 1 106). The use of (R)-cysteine isopropyl ester instead of the methyl ester (85) gave the corresponding (5S)-methyl isomer (86a) more stereoselectively. 

With glycine ethyl ester and cysteine methyl ester in the presence of nickelous and cupric ions, a small increase in the (alkaline) bimolecular rate constant was shown to parallel an increase in the stability of the metal-ion complex (65),... 

Dihydrogen evolves from vanadium(II)-cysteine at pH6.0-9.5. This reduction is first order in V11 and independent of pH in the range 7.5-8.5. If cysteamine or cysteine methyl ester is used, dihydrogen is still evolved. The reaction with serine is 1000 times slower than with cysteine even though the half wave potentials are comparable.156 This reaction may be explained by a hydride pathway similar to that proposed for catechol complexes or alternatively Scheme 8. 

Sexual conjugation in yeast is also induced by pheromones (mating factors).325-327 Yeast cells of mating type a synthesize the 12-residue mating factor a which contains a C-terminal cysteine methyl ester S-alkylated with a frans,frans-farnesyl group (Table 30-5). Cells of type a synthesize a 13-residue factor ol 327a Cells are attracted to the pheromone produced by cells of the opposite type. The tremerogens, sex hormones of certain basidiomycetes, have related structures (Table 30-5)328... 

The thione is prepared by reaction of L-cysteine methyl ester hydrochloride and CS2 in the presence of N(C2H5)3.1... 

Bacteria (modified) bioaccumulation Carbon powder sorbents modified with L-cysteine methyl ester FIBAN-As (Ion-exchange polymeric fibers impregnated with iron (oxy)(hydr)oxides)... 

Tremmel and Geyer from glucuronolactone and cysteine methyl ester and demonstrated to adopt a PII helical conformation in oligomers [5],... 

Stimmel, J. B., Deschenes, R. J., Volker, C., Stock, J., and Clarke, S. (1990) Evidence for an S-farnesyl cysteine methyl ester at the carboxyl terminus of the Saccharomyces RAS 2 protein, Biochemistry 29, 9651-9659. 

The N-alkylation of L-cysteine results from a series of reactions involving the condensation of L-cysteine methyl ester (605) with ethyl iminoacetate (606), followed by A-alkylation of the intermediate 4-methoxycarbonyl-2-methylthiazoline (607). Acid hydrolysis of the thiazolinium salt (608 Scheme 301) then gives (609) (70ACS(B)3129). 

L-Cysteine methyl ester hydrochloride Cysteine, methyl ester, hydrochloride, L- (8) L-Cysteine, methyl ester, hydrochloride (9) (18598-63-5)... 

PEPTIDE SYNTHESIS USING l-(4-CHL0R0PHENYL)-3-(4 -METHYL-l -PIPERAZINYL)-2-PR0PYN-l-0NE AS REAGENT BENZYLOXYCARBONYL-L-ALANYL-L-CYSTEINE METHYL ESTER AND BENZYLOXYCARBONYL-L-ASPARTYL-(tert-BUTYL ESTER)-L-PHENYLALANYL-L-VALINE METHYL ESTER... 

From the (/ )-cysteine methyl ester 22 the thi-azolidine 9 is obtained, which can be deproto-nated with LDA. The attack of the methyl iodide on the enolate takes place from the side opposite to the bulky terr-butyl group (23 10). The auxiliary chiral center is removed under acidic conditions and (/ )-2-methylcysteine methyl ester hydrochloride Sb X FICI is obtained. (S)-2-Methyl-cysteine methyl ester hydrochloride ent-5b X FlCl can be prepared in the same way from (Sl-cysteine. 

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