We have identified an iron porphyrin catalyst [Fe(T4CPP)Cl] that is effective to cross-couple alkenes with benzyl bromides via radical intermediates, even when two benzyl radicals of similar stability are formed as intermediates. This "radical sorting" strategy 10 has proven effective in dual catalysis systems with intersecting cycles; disclosed here is compression of reactivity into a single catalyst. In addition, no prior method has coupled two different benzylic radicals, which can undergo competitive background homodimerization. The basis for the unique behavior of Fe(T4CPP)Cl versus Fe(TPP)Cl is unclear but may relate to its aggregation state and/or its partition between different elementary steps in the catalytic cycles. This investigation is underway. Fe(T4CPP)-H must also cause an alkene MHAT faster than a hydrogen evolution reaction (HER) between two iron hydrides, 8 possibly by polarization of the intermediate Fe-H bond to provide it protic character. We cannot conclusively rule out HAT from a ligand-bound hydrogen, 33 although isotope labeling of related ligand classes has not uncovered evidence of metal to carbon migration of hydride. Because the alkene reduces the Fe 3+ -H to Fe 2+ and the benzyl bromide oxidizes Fe 2+ to Fe 3+ , the catalytic cycle is redox neutral overall and thus circumvents the need for exogenous oxidant. The coupling scope includes mono-, di-, tri-and tetrasubstituted alkenes among conjugated and unconjugated alkenes alike. When styrenes are used as substrates, two similar benzyl radicals are produced as intermediates, yet the heterodimeric products predominate. The hypothesis that best fits the data involves sequential MHAT and SH2 steps (see Figure ) mediated by the same iron porphyrin catalyst. In contrast to precious metal catalysts, alkenes are functionalized by these base metal complexes without the need for either carbon to coordinate the metal center. As a result, these systems represent powerful platforms for the synthesis and modification of natural products in which alkenes are often crowded and unreactive towards traditional metal complexes.