Optically active 4-hydroxy-2-cyclopentenones, and their production

摘要

A process for preparing an optically active 4-hydroxy-2-cyclopentenone of the formula: (I) wherein R1 is a hydrogen atom or a methyl group, R2 is an alkyl group, an alkenyl group or an alkynyl group and the asterisk (*) indicates an asymmetric configuration, which comprises subjecting an optically active 4-cyclopentenone-alcohol of the formula: (II) wherein R1 and R2 are each as defined above, the asterisk (*) indicates an asymmetric configuration and the substituents R1 and R2 take a cis-configuration to rearrangement while maintaining the original steric configuration.