Catalytic Generation of Donor-Acceptor Cyclopropanes under N-Heterocyclic Carbene Activation and their Stereoselective Reaction with Alkylideneoxindoles

Abstract

Formylcyclopropanes undergo activation in the presence of an N-heterocyclic carbene catalyst generating a donor-acceptor cyclopropane intermediate with the ability to undergo ring-opening followed by formal [4+2] cycloaddition with alkylideneoxindoles. This enables the direct enantio- and diastereoselective synthesis of tetrahydropyrano[ 2,3-b]indoles through the use of a chiral NHC catalyst. Keywords: asymmetric