Nickel-Catalyzed Cyanation of Aryl Halides and Hydrocyanation of Alkynes via C-CN Bond Cleavage and Cyano Transfer

Abstract

We report the nickel-catalyzed cyanation and hydrocynation methods to prepare aryl nitriles and vinyl nitriles from aryl halides and alkynes, respectively. Using cheap and nontoxic 4-cyanopyridine N-oxide as the cyano shuttle, the methods provide an efficient approach to prepare aryl cyanides and vinyl nitriles under mild and operationally simple reaction conditions with a broad range of functional group tolerance. In hydrocyanation of alkynes, the method demonstrated good regioselectivity, producing predominantly E or Z-alkenyl nitriles in a controlled manner and exclusively Markovnikov vinyl nitriles when internal diaryl alkynes and terminal alkynes were applied as the substrates, respectively. The preliminary mechanistic investigation indicated that C-CN bond cleavage process is promoted by oxidative addition to nickel(I) complex in the cyanation of aryl halides, and the further studies via a series of deuterium exchange experiments indicated that water serves as the hydrogen source for the hydrocyanation of alkynes