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A visible light responsive catalytic system with the B12 complex as the catalyst and [Ir(dtbbpy)(ppy)2]PF6 as the photosensitizer was developed. It provides a convenient and efficient way to synthesize amides. Based on this method, trichlorinated organic compounds were converted into amides in the presence of an amine under aerobic conditions at room temperature in a one‐pot procedure. Various trichlorinated organic compounds and an amine source, such as primary, secondary, and cyclic amines, have been evaluated for this transformation, providing the expected products in moderate to excellent yields. Notably, product formation depended on the reaction atmosphere where the amide was obtained under aerobic conditions while partially dechlorinated products were obtained under anaerobic conditions. As this protocol is free from hazardous reagents, extra additives, noble metals, and dangerous gas, the present method provides a novel and efficient approach for amide synthesis under mild and easily controlled conditions. I see the light: A visible light responsive catalytic system with the B12 complex as the catalyst and [Ir(dtbbpy)(ppy)2]PF6 as the photosensitizer has been developed, and provides a convenient and efficient method for amide formation under air at room temperature. This protocol is free from hazardous reagents, extra additives, noble metals as well as dangerous gas and was applied to a wide range of trichlorinated organic compounds as the substrate to form a variety of amides (see figure). [ABSTRACT FROM AUTHOR]

A visible light induced three-component catalytic system with the cobalamin derivative (B12) as a catalyst, the cyclometalated iridium(iii) complex (Irdfppy, Irppy, Irpbt and [Ir{dF(CF3)ppy}2(dtbpy)]PF6) as a photosensitizer and triethanolamine as an electron source under N2 was developed. This catalytic system showed a much higher catalytic efficiency than the previous catalytic system using [Ru(ii)(bpy)3]Cl2 as the photosensitizer for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT). Noteworthy is the fact that the remarkable high turnover number (over ten thousand) based on B12, which ranks at the top among the reported studies, was obtained when Irdfppy was used as a photosensitizer. This photocatalytic system was also successfully applied to the B12 enzyme-mimic reaction, i.e., the 1,2-migration of the phenyl group of 2-bromomethyl-2-phenylmalonate. The plausible reaction mechanism was proposed, which involved two quenching pathways, an oxidative quenching pathway and a reductive quenching pathway, to be responsible for the initial electron transfer of the excited-state photosensitizers during the DDT dechlorination reaction. Transient photoluminescence experiments revealed that the oxidative quenching of the photosensitizer dominated over the reductive quenching pathway. [ABSTRACT FROM AUTHOR]

Visible‐light‐driven organic synthesis is a green and sustainable method for producing fine chemicals and is highly desirable at both laboratory and industrial scales. In this study, we developed a broad‐range (including the red region) visible‐light‐driven carbonylation of CCl4, CBr4, and CBr3F with nucleophiles, such as amines and alcohols, using a B12−Mg2+/TiO2 hybrid catalyst. Carbonyl molecules such as ureas, carbamates, carbonate esters, and carbamoyl fluorides were synthesized with high selectivity and efficiency under mild conditions. Diffuse reflectance UV‐vis spectroscopy, femtosecond time‐resolved diffuse reflectance spectroscopy, and density functional theory calculations revealed the reaction mechanism is a combination of SN2 and single‐electron transfer. This is a rare example of a low‐energy, red‐light‐driven photocatalysis, which has been a highly desired organic reaction in recent years. We believe that this study provides a general platform to access diverse carbonyl molecules and could promote photocatalytic carbonylation reactions on a pilot scale. [ABSTRACT FROM AUTHOR]

The hybrid catalyst composed of the B 12 complex and rhodium ion (Rh3+) modified titanium oxide was synthesized for the visible light-driven B 12 inspired catalytic reaction. The hybrid catalyst contains 4.93 × 10−6 molg−1 of the B 12 complex and 5.43 × 10−5 molg−1 of the Rh(III) ion on the surface of titanium oxide. Visible light irradiation (λ ≧ 420 nm) of the hybrid catalyst in the presence of triethylamine (Et 3 N) as a sacrificial reagent showed absorption at 390 nm, typical for the Co(I) state of the B 12 complex monitored by diffuse reflectance UV–vis analysis, which imply that electron transfer from the titanium oxide to Co(III) center of the B 12 complex occurred by the visible light irradiation. Benzotrichloride was converted to N , N -diethylbenzamide by the visible light irradiation catalyzed by the hybrid catalyst in air at room temperature. Both the conduction band electron and valence band hole of the catalyst were utilized for the reaction to form the amide product. The reaction mechanism of the duet reaction was proposed. Image 1 • The hybrid catalyst composed of the B 12 complex, rhodium (III) ion, and TiO 2 was synthesized. • Various amides were formed from the benzotrichloride derivative by the B 12 modified visible light-driven photocatalyst under mild conditions. [ABSTRACT FROM AUTHOR]