Transition-metal-catalyzed remote meta-C–H alkylation and alkynylation of aryl sulfonic acids enabled by an indolyl template

ATransition-metal-catalyzed remote sp2C–H functionalization of aryl sulfonic acids was hardly ever realized owing to competitive ortho-C–H functionalization of aryl sulfonates and electron-deficient nature of phenyl ring. Herein, with the assistance of a practical biaryl indolyl directing template, palladium-catalyzed remote sp2C–H alkylation of aryl sulfonic acids have been achieved in moderate to good yields with exclusive meta selectivity. Moreover, remote meta-selective C–H alkynylation of aryl sulfonic acids was also accomplished with a rhodium catalyst. These meta-C–H functionalized products proved to be the superior synthetic precursors, which are difficult to access using the conventional strategy.