Highly enantioselective nickel-catalyzed intramolecular reductive cyclization of alkynones.

The first asymmetric nickel-catalyzed intramolecular reductive cyclization of alkynones is reported. A P-chiral monophosphine and triethylsilane were used as the ligand and the reducing reagent, respectively, to form a series of tertiary allylic alcohols bearing furan/pyran rings in excellent yields and enantioselectivities. This reaction has a broad substrate scope and enabled the efficient synthesis of dehydroxycubebin and chiral dibenzocyclooctadiene skeletons.