Palladium‐Catalyzed CH Functionalization via Transient Directing Group Strategy

Abstract

Abstract Transition metal‐catalyzed carbon–hydrogen bond (CH) activation and functionalization have exponentially developed in the past 30 years. The use of transition‐metal catalysts in combination with directing groups enables the site‐selective CH activation and functionalization to occur even at inactivated and less reactive sites. To avoid the extra steps to introduce directing groups at specific sites in the substrates and to remove these groups before producing the final products, a new transient directing group strategy using temporarily installed coordinating auxiliaries has been devised for CH bond activation, which allows the temporarily and reversibly installment of a catalytic amount of a coordinating auxiliary and achieve the regioselective CH bond functionalization. In this article, palladium‐catalyzed functionalization of C(sp 2 )H and C(sp 3 )H bonds mediated by transient imine‐directed ligands was discussed, which allowed the efficient construction of new carbon−carbon and carbon−heteroatom bonds from various types of CH bonds.