Enantioselective gold(i)-catalyzed rearrangement of cyclopropyl-substituted 1,6-enynes into 2-oxocyclobutyl-cyclopentanes

Abstract

A gold(I)-catalyzed cycloisomerization/ring expansion sequence allows the highly enantioselective synthesis of 2-oxocyclobutylcyclopentane derivatives from cyclopropyl-substituted enynes. The bimetallic [(R)-MeO-DTBM-BIPHEP-(AuCl)₂] complex was found to be the best precatalyst, affording the desired cyclobutanones in high yields and enantioselectivities (up to 99% ee). The usefulness of the method was further demonstrated by preparing the tricyclic core scaffold of russujaponol D.