Enantioconvergent synthesis of (−)‐(S)‐ and (+)‐( R )‐2‐acetyl‐3,6‐dihydroxycyclohex‐2‐enone starting from rac ‐6‐hydroxy‐3‐methoxycyclohex‐2‐enone

The synthesis of enantiomerically pure (−)‐( S )‐ and (+)‐( R )‐2‐acyl‐3,6‐dihydroxycyclohex‐2‐enone starting from diastereomerically pure N‐tosyl‐( S )‐proline esters 3‐methoxy‐6‐hydroxycyclohex‐2‐enone 1 is presented. An enantioconvergent synthesis of either (−)‐( S )‐ and (+)‐( R )‐2‐acyl‐3,6‐dihydroxycyclohex‐2‐enone starting with the racemic α‐ketol 1 through a conversion of (∼1:1) mixture of diastereomeric esters into one diastereomer by a repeated crystallization, followed by dimethylaminopyridine‐catalyzed equilibration as key steps is described. Chirality 13:488–492, 2001. © 2001 Wiley‐Liss, Inc.