Methoxy-Directed Aryl-to-Aryl 1,3-Rhodium Migration

Through-space metal/hydrogen shift is an important strategy for transition-metal-catalyzed C–H bond activation. Here we describe the synthesis and characterization of a Rh­(I) 2,6-dimethoxybenzoate complex that underwent stoichiometric rearrangement via a highly unusual 1,3-rhodium migration. This aryl-to-aryl 1,3-Rh/H shift was also demonstrated in a Rh­(I)-catalyzed decarboxylative conjugate addition to form a C–C bond at a meta position instead of the ipso-carboxyl position. A deuterium-labeling study under the conditions of Rh­(I)-catalyzed protodecarboxylation revealed the involvement of an ortho-methoxy group in a multistep pathway of consecutive sp3 and sp2 C–H bond activations.