Stereospecific Synthesis of Alkylidenecyclopropanes via Sequential Cyclopropene Carbomagnesation/1,3-Carbon Shift

Alkylidenecyclopropanes can be synthesized from enantiomerically enriched cyclopropene derivatives with > 99% stereotransfer and good to excellent yield. The protocol comprises the stereoselective reaction of Grignard reagents with 1-alkoxymethyl-3-hydroxymethylcyclopropenes and a stereospecific [1,3] carbon shift reaction.