Palladium‐Catalyzed ortho‐Aroylation of 2‐Arylbenzothiazoles and 2‐Arylbenzoxazoles with Aldehydes

An efficient protocol for the ortho‐aroylation of 2‐arylbenzothiazoles and 2‐arylbenzoxazoles has been developed using aldehydes as the aroyl source. This Pd‐catalyzed substrate‐directed sp2‐hybridized C–H bond functionalization occurs in the presence of the oxidant tert‐butyl hydroperoxide. A variety of functional groups on the 2‐arylbenzothiazoles, 2‐arylbenzoxazoles, and aldehydes are tolerated under the reaction conditions. Regioselective aroylation at the less hindered ortho position was observed for meta‐substituted 2‐arylbenzothiazoles.