Enantioselective Nickel?Catalyzed anti ?Arylmetallative Cyclizations onto Acyclic Ketones

Domino reactions involving nickel?catalyzed additions of (hetero)arylboronic acids to alkynes, followed by cyclization of the alkenylnickel intermediates onto tethered acyclic ketones to give chiral tertiary?alcohol?containing products in high enantioselectivities, are described. The reversible E/Z isomerization of the alkenylnickel intermediates enables overall anti?arylmetallative cyclization to occur. The ring system of the products are substructures of certain diarylindolizidine alkaloids