Understanding the Activation of Air-Stable Ir(COD)(Phen)Cl Precatalyst for C–H Borylation of Aromatics and Heteroaromatics

A newly developed robust catalyst [Ir(COD)(Phen)Cl] (A) was used for the C-H borylation of three dozen aromatics and heteroaromatics with excellent yield and selectivity. Activation of the catalyst was identified by the use of catalytic amounts of water, alcohols, etc., when B₂pin₂ was used in noncoordinating solvents, while for THF catalytic use of HBpin was required. The results were on par with the in situ based expensive system [Ir(OMe)(COD)]₂/dtbbpy or Me₄Phen.