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Hydrogen-Bonding Controlled Nickel-Catalyzed Regioselective Cyclotrimerization of Terminal Alkynes
Kai Yang1, Pengfei Wang1, Ze-Ying Sun1
1Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, P. R. China.
Abstract:
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 NiCl2·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.
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