Borylation of Aryldiazonium Ions with N-Heterocyclic Carbene−Palladium Catalysts Formed without Added Base

A highly efficient catalytic borylation process with aryldiazonium ions was developed using a carbene−palladium catalyst formed in situ to give arylpinacolatoborane products. An X-ray structure for the N-heterocyclic carbene−palladium complex, used as the catalyst formed from bis(2,6-diisopropylphenyl)-4,5-dihydroimidazolium chloride, was obtained without added base.