Synthesis of Enantioenriched Allenes from 1,1-Cyclopropanediesters

Significance

In this paper the authors report a protocol allowing the formation of chiral allenes via S_N2′ addition of organocuprates to enantioenriched propargylcyclopropanes. Development of such a method is important in light of high synthetic utility of chiral allenes, which lacked an expedient synthetic approach thus far despite a number of reports. Under optimized conditions, a range of 1,7-addition products was obtained with 78-89% yields. Complete preservation of enantiomeric purity was observed for an enantioenriched substrate 1, leading to a synthetic precursor of a pheromone 2 of Acanthoscelides obtectus.