1,4-migration of rhodium and palladium in catalytic organometallic reactions

Mechanisms based on the 1,4-migration of metal centers have been proposed to explain some interesting transition-metal-catalyzed organic transformations. Despite the lack of solid evidence for the real nature of this process, the 1,4-metal migration reaction is proposed to proceed by the reductive elimination of trivalent intermediates for the Rh-involved reactions and of tetravalent intermediates for the Pd-catalyzed processes. These high-valent organometallic species would be formed by the oxidative addition to C-H and C-X bonds. This minireview summarizes the results in this area.