NaBArF4‐Catalyzed Oxidative Cyclization of 1,5‐ and 1,6‐Diynes: Efficient and Divergent Synthesis of Functionalized γ‐ and δ‐Lactams.

Summary of main observation and conclusion: An efficient NaBArF4‐catalyzed oxidative cyclization of readily available 1,5‐ and 1,6‐diynes has been developed. Importantly, this transition metal‐free oxidative catalysis proceeds via a presumable Lewis acid‐catalyzed SN2' pathway, which is distinct from the relevant oxidative rhodium and gold catalysis. This method leads to the facile and practical construction of a diverse range of synthetically useful γ‐ and δ‐lactams in mostly good to excellent yields with broad substrate scope. We report a NaBArF4‐catalyzed oxidative cyclization of 1,5‐ and 1,6‐diynes via a presumable Lewis acid‐catalyzed SN2' pathway. This method leads to the efficient and practical construction of a diverse range of synthetically useful γ‐ and δ‐lactams in mostly good to excellent yields with broad substrate scope. [ABSTRACT FROM AUTHOR]