Hisashi Shimakoshi

This concept focuses on dual‐catalysis using metal complexes and heterogeneous photocatalysts. Vitamin B 12 derivatives are sophisticated metal complexes that facilitate enzymatic reactions in the biological systems. The B 12 enzymes inspired reactions catalytically proceed in dual‐catalyst systems of B 12 derivatives and heterogeneous photocatalysts, such as titanium oxide (TiO 2 ) and metal‐organic frameworks (MOFs), under light irradiation. The cobalt ions in B 12 derivatives are effectively reduced by photoexcited photocatalysts, producing low‐valent Co(I) species. The photoinduced nucleophilic Co(I) species react with an alkyl halide to form an organometallic complex with a Co−C bond. The Co−C bond dissociates during photolysis to generate alkyl radicals. Based on this mechanism, dual‐catalysis effectively promotes various light‐driven organic syntheses and light‐driven dehalogenation reactions of toxic alkyl halides. The trends of the dual‐catalyst system and recent progress in this field are discussed in this concept.