The configurational stability of an enantioenriched alpha-thiobenzyllithium derivative and the stereochemical course of its electrophilic substitution reactions; Synthesis of enantiomerically pure, tertiary benzylic thiols

The lithium compound (S)-7, formed by deprotonation of the (S)-S-1-phenylet hyl thiocarbamate (S)-10, is configurationally stable at -70 degreesC. Even at elevated temperatures it racemizes only very slowly. It represents the first essentially enantiopure alpha -thiocarbanion derivative and can be ut ilized in asymmetric synthesis. Most electrophiles (except proton acids) ad d to (S)-7 with complete stereoinversion. Cleavage of the substitution prod ucts leads to practically enantiopure, tertiary 1-phenylalkanethiols.