Synthesis of Functionalized Alkylidenecyclopropanes by Ireland-Claisen Rearrangement of Cyclopropenylcarbinyl Esters

Glycolates or glycinates derived from diversely substituted secondary cyclopropenylcarbinols have been involved for the first time in an Ireland-Claisen rearrangement. This reaction allows an efficient and stereoselective access to highly functionalized alkylidenecyclopropanes possessing an alpha-hydroxy or a-amino acid subunit, which in turn are valuable precursors of substituted cyclopropanes by diastereoselective hydrogenation of the exocyclic alkene.