Nickel/N-Heterocyclic Carbene-Catalyzed Suzuki-Miyaura Type Cross-Coupling of Aryl Carbamates.

The utility of N-heterocyclic carbene ligands in nickel-catalyzed Suzuki-Miyaura cross-coupling of aryl esters and carbamates is investigated. Imidazol-2-ylidene bearing 2-adamantyl groups at its nitrogen atoms generates the most active nickel species among the ligands examined, allowing cross-coupling of a range of aryl carbamates and pivalates. Unlike the previously reported system using tricyclohexylphosphine, this protocol is suitable for the cross-coupling using arylboronic esters in addition to arylboronic acids.