Patent ID: 6878828

Claim:
A method of preparing an optically active 2-alkylated cysteine represented by Structural Formula (I): or a salt thereof; wherein R 1 is a substituted or unsubstituted alkyl group, the method comprising: (a) coupling a compound represented by Structural Formula (II): or a salt thereof, with a substituted or unsubstituted aryl nitrile of the formula Ar—CN, wherein Ar is a substituted or unsubstituted aryl group; thereby forming a substituted thiazoline carboxylic acid represented by Structural Formula (III): (b) esterifying the substituted thiazoline carboxylic acid with R*—OH, wherein R* is a substituted or unsubstituted alkyl group comprising one or more chiral carbon atoms; thereby forming a substituted thiazoline carboxylic acid ester represented by Structural Formula (IV): (c) alkylating the substituted thiazoline carboxylic acid ester with one or more bases and R 1 X, wherein X is a leaving group and R 1 is as defined above; thereby forming an alkylated substituted thiazoline carboxylic acid ester represented by Structural Formula (V): (d) hydrolyzing the alkylated substituted thiazoline carboxylic acid ester with base or acid, thereby forming an alkylated substituted thiazoline carboxylic acid represented by Structural Formula (VI): (e) reacting the alkylated substituted thiazoline carboxylic acid with acid, thereby forming the 2-alkylated cysteine represented by Structural Formula (I).