Construction of an enantiomerically pure 6-substituted 3,5-syn-dihydroxyhexanoic acid system by an enantioselective deprotonation strategy: formal synthesis of an antiobesity agent, (-)-tetrahydrolipstatin.

Preparation of 6-substituted 4-hydroxytetrahydro-2H-pyran-2-one (12), a key intermediate for the synthesis of (-)-tetrahydrolipstatin, was achieved in an optically pure form by employing an enantioselective deprotonation reaction of the prochiral bicyclic derivative (5) as a key step.