A cyclopropanol approach to the synthesis of both enantiomers of the C13-C21 fragment of epothilones

Efficient syntheses of both enantiomers of the C13-C21 fragment of epothilone molecules have been performed by use of enantiomeric oxiranyl-substituted cyclopropylsulfonates as key intermediates. The latter were obtained by the cyclopropanation of easily available (R)-methyl 2,3-O-isopropylideneglycerate and subsequent manipulation of the functional groups. Asymmetric allylation of 1-formylcyclopropyl pivalate led to an alternative precursor of the target compounds with moderate enantioselectivity.