We have developed a versatile method for the synthesis of enantiomerically pure cis-2- methylcyclopropanecarboxylic acid (−)-2, a component of curacin A, and its enantiomer,(+)- 2. Double-asymmetric Simmons-Smith cyclopropanation of the dienes 5 and 9 derived from diethyl L-tartrate proceeded with excellent diastereofacial selectivity (> 99% de) to give the dicyclopropanes 6 and 10, which were converted to both enantiomers of 2.
