Regiocontroled Palladium-Catalysed Direct Arylation at Carbon C2 of Benzofurans using Benzenesulfonyl Chlorides as the Coupling Partners

摘要

The regioselective palladium-catalysed direct arylation of benzofurans with aryl halides is a challenging reaction because carbons C2 and C3 display similar reactivity. Such couplings generally lead to mixtures of C2 and C3 arylation products together with C2,C3 diarylation products. We found that the use of benzenesulfonyl chlorides instead of aryl halides as the coupling partner allows for controlling the regioselectivity of the palladium-catalysed arylation of benzofurans in favour of carbon C2. This method tolerates a variety of substituents on the benzenesulfonyl derivative.