Hydrogen-Bonding Controlled Nickel-Catalyzed Regioselective Cyclotrimerization of Terminal Alkynes

Herein we report a hydrogen-bonding controlled nickel-catalyzed regioselective cyclotrimerization of terminal alkynes in moderate to excellent yields with high regioselectivities toward 1,3,5-trisubstituted benzenes. This method features a cheap catalyst, mild reaction conditions, and excellent functional group compatibility. The Ni–B(OH) 2 complex in situ generated from NiCl 2 ·DME and tetrahydroxydiboron might act as an active catalyst. After three consecutive cis -additions of terminal alkynes, internal migratory insertion cyclization, and β-boron elimination induced aromatization, 1,3,5-trisubstituted benzenes were selectively established.