Asymmetric cyclopentannelation. Chiral auxiliary on the allene.

An enantioselective variant of the synthesis of cross-conjugated cyclopentenones, based on D-glucose-derived chiral auxiliaries, is described. Minor modification of the method makes it applicable to the preparation of both enantiomeric series of products. Both enantiomers of the key intermediate in our roseophilin synthesis have been prepared.