Efficient synthesis of tetracyclic γ-lactams via gold-catalyzed oxidative cyclization of alkenyl diynes

An efficient gold-catalyzed cascade cyclization of alkenyl diynes involving alkyne oxidation, carbene-alkyne metathesis and cyclopropanation has been developed, furnishing a series of tetracyclic gamma-lactams bearing one quaternary carbon center and one tertiary carbon center in moderate to good yields with excellent diastereoselectivities. In addition, the proposed mechanistic rationale for this oxidative cyclization is well supported by theoretical calculations.

Automated summary

An efficient gold-catalyzed cascade cyclization has been developed for the synthesis of tetracyclic gamma-lactams bearing one quaternary carbon center and one tertiary carbon center. The reaction involves alkyne oxidation, carbene-alkyne metathesis, and cyclopropanation, and exhibits moderate to good yields with excellent diastereoselectivities. The proposed mechanistic rationale is well supported by theoretical calculations.