A divergent approach to the preparation of cysteine and serine analogs
Malonate diesters containing a prochiral quaternary carbon have been successfully transformed into analogs of cysteine and serine. The chiral half-esters are obtained in good yield, and enantioselectivity by selective hydrolysis using Pig-Liver Esterase (PLE) as the catalyst. The resulting half-ester intermediates are transformed into alpha(2,2-), beta(2.2-), and beta(3.3)-analogs of cysteine and serine. The methodology described here allows for the preparation of both enantiomers of the amino-acid analogs by selective manipulation of the ester and acid functional I ties. This divergent strategy allows a common synthetic strategy to be used to prepare a variety of unnatural amino-acid classes from a common intermediate which should prove useful in the design of novel peptide libraries. Copyright (C) 2008 European Peptide Society and John Wiley & Sons. Ltd.