Deracemization of alpha-substituted arylacetic acids

Reaction of rac-alpha-substituted arylacetyl chlorides with (R)- and (S)-3-hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone under standard esterification conditions, gave esters (3R,alpha R)- and (3S,alpha S)-3, respectively, with a diastereoselectivity which diminishes on increasing the steric effect of the alpha-substituent. Controlled acidic hydrolysis of esters 3 afforded the corresponding acids 4 with minimal racemization. Boron tribromide demethylation of (R)- and (S)-4d gave without racemization the hydroxyacids (R)- and (S)-4e, known precursors of (R)- and (S)-iodoalphionic acid. Copyright (C) 1996 Elsevier Science Ltd