Coupling of N-heterocycle-fused enyne aldehydes with γ,δ-unsaturated Fischer carbene complexes

The coupling of gamma,delta-unsaturated Fischer carbene complexes with enyne aldehyde derivatives fused to indole, imidazole, and pyrazole ring systems has been examined. The reaction leads to heterocycles fused to the hydronaphthalene ring system in a single step. The products of the reaction feature heterocycles fused either to benzene rings or to a cyclohexane ring. The product distribution correlates with the electronic richness of the heterocyclic ring. A moderate degree of diastereoselectivity was observed using heterocycles featuring chiral nitrogen substituents.