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.