Enantioselective Nickel-Catalyzed <i>anti</i>-Carbometallative Cyclizations of Alkynyl Electrophiles Enabled by Reversible Alkenylnickel <i>E</i>/<i>Z</i> Isomerization

Nickel-catalyzed additions of arylboronic acids to alkynes, followed by enantioselective cyclizations of the alkenylnickel species onto tethered ketones or enones, are reported. These reactions are reliant upon the formal <i>anti</i>-carbonickelation of the alkyne, which is postulated to occur by the reversible <i>E</i>/<i>Z</i> isomerization of an alkenylnickel species