Copper-catalysed borylation of aryl chlorides

We report herein the first Cu-catalysed borylation of a wide range of aryl chlorides with different electronic and steric properties using a readily prepared NHC-stabilised Cu catalyst and KO^tBu as the base with B₂pin₂ (pin = pinacolato) as the boron reagent. The aryl chlorides are converted into their corresponding arylboronic esters in good yields. The new procedure shows broad functional group tolerance, and B₂neop₂ (neop = neopentyl glycolato) can also be applied as the boron reagent.