2.14 Manganese-, Iron-, and Cobalt-Catalyzed Radical Alkene Hydrofunctionalization

Abstract This review highlights select methods from the synthetic organic metal hydride hydrogen-atom transfer (MHAT) literature. Following MHAT to an alkene, carbon-centered radicals are captured to forge bonds between carbon and hydrogen, oxygen, nitrogen, the metal center itself, or other atoms. Isomerization is also known, proceeding via abstraction of an adjacent hydrogen atom. Oxidation or reduction of the MHAT-generated carbon-centered radical allows for coupling with two-electron nucleophiles or electrophiles in radical–polar crossover methods. Cross-coupling-type transformations have also emerged, enabled by secondary metal capture of the radical intermediate. The field is evolving from classical catalytic turnover (oxidation/hydride reduction) to other modes of reductive turnover, primarily represented by photocatalytic and electrochemical methods. Opportunities for novel modes of turnover, enantioselective synthesis, and mechanism interrogation promise to drive the MHAT field forward.