Palladium-Catalyzed Phosphine-Free Direct C–H Arylation of Benzothiophenes and Benzofurans Involving MIDA Boronates.

With high regioselectivity, a series of benzoheterocyclic compounds were synthesized via palladiium-catalyzed phosphine-free C–H arylation of benzothiophenes/benzofurans with aryl MIDA boronates at 30-50 °C in moderate to excellent yields. MIDA boronates were used in C–H arylation of heterocycles for the first time. Under the optimal conditions, the benzothiophenes could be transformed into the β-arylbenzothiophenes, and the benzofurans gave only α-aryl-substituted products. [ABSTRACT FROM AUTHOR]