Nickel-Catalyzed Cyanation of (Hetero)aryl Bromides Using DABAL-Me3 as a Soluble Reductant.

Abstract

A nickel-catalyzed cyanation of (hetero)aryl halides using air-stable bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane (DABAL-Me3) as a soluble reductant has been developed. The reaction uses readily available and inexpensive Ni(dppf)Cl2 as a precatalyst, a substoichiometric amount of Zn(CN)2, and DABAL-Me3 as an alternative to commonly prescribed insoluble reductants. We found the addition of catalytic tetrabutylammonium bromide (TBABr) to be beneficial, due to facilitating dissolution of low levels of the cyanide salt (confirmed via a control study). Similarly, slow addition of a tetrabutylammonium cyanide (TBACN) solution is effective and results in a completely homogeneous reaction mixture.