Nickel-catalyzed [2 + 2 + 2] benzannulation of alkynes: a new route to the synthesis of highly substituted naphthalenes

Abstract

The Ni(II)-catalyzed aromatic homologation of various directing groups with alkynes to afford highly substituted naphthalene products via C–X bond cleavage followed by alkyne insertion and C–H activation is described. This reaction proceeded with a wide range of directing groups such as pyrazoles, imidazopyridines, benzoimidazothiazoles, thiazoles and triazoles with alkynes to afford highly substituted naphthalenes in moderate to good yields. This transformation is promoted by a simple, straightforward combination of a Ni(II)-complex, Zn dust and a base.