Formal insertion of selenoketenes into donor–acceptor cyclopropanes: mesomeric alkynylselenolates as key starting materials

Abstract

Donor–acceptor cyclopropanes (DACs) react with lithium alkynylselenolates in the presence of In(OTf)₃ to furnish tetrahydroselenophenes with exocyclic double bonds. The reaction can be regarded as a formal insertion of selenoketenes into the strained three-membered ring systems. Lithium alkynylselenolates are generated in situ from lithium acetylides and elemental selenium. The reactions afford tetrahydroselenophenes with a broad substrate scope and high yields (up to 95%).