Enantioselective reductive cyclization of alkynals via cobalt catalysis

Abstract

Transition metal-catalyzed asymmetric intermolecular reductive coupling of alkynes and aldehydes has been well-established for constructing chiral allylic alcohols. In contrast, the intramolecular variant remains underexplored. Herein, we present a cobalt-catalyzed reductive cyclization of alkynals, providing chiral 4-chromanols with high efficiency (83% average yield), good to excellent enantioselectivities (85%–96% ee), and broad functional group tolerance. Moreover, preliminary bioactivity studies against human hepatocellular carcinoma cells has also been performed.