The vernal blooming of green chemistry has contributed to the development of visible light catalysis. Active radical species are generatedf rom catalytic amounts of photosensitizers,such as transition-metal complexes and organic dyes, upon visible light irradiation. Stoichiometrica mounts of oxidants, reductants, and radical initiators are avoidedi n most cases. Thus, reactions proceed under milder conditions with ab roader functional group tolerance than found by other methods. Photoredoxc atalysis has been used to form CÀCa nd CÀX( X= O, N, and S) bonds but is comparably underdeveloped in organophosphorus chemistry.H erein, we summarize advances in photoredox catalysis that involve organophosphorus chemistry.T he synthesis of organophosphorusc ompounds by photoredox catalysis, transition-metal complex/photoredoxd ual catalytic systems, andp hotoredox catalysis with phosphorus organocatalysts are discussed. The shortcomings and possible future trendso ft his chemistry are also presented.Scheme1.Various photocatalysts for the cross-couplingr eactionso ftetrahydroisoquinoline with dialkylphophonates and diaryl phosphine oxides[ ppy = 2phenylpyridine, bpy = 2,2'-bipyridine, DMF = N,N-dimethylformamide, AIBN = azobis(isobutyronitrile), PVA = poly(vinyl alcohol), BTF = benzotrifluoride].Scheme3.Thiophosphite-mediated RATC process to form five-membered ring and C sp 3 ÀPb ond.Scheme2.The mechanism for the photocatalyzed cross-coupling reaction [PC = Ir complex, Au complex, eosin Y, or rose bengal)].Scheme9.Direct CÀHp hosphorylationoft hiazoles in cross-coupling hydrogen evolution reaction and the proposed mechanism.Scheme11. Hetero-cross-dehydrogenative-coupling reaction of benzothiazoles and H-phosphonates.Scheme10. Hetero-cross-dehydrogenative-coupling reaction of dialkylphosphiteswith N-protected indole and the tentative reaction mechanism.

Visible light along with 5 mol % eosin B catalyzed the first direct C-H phosphorylation of thiazole derivatives with diarylphosphine oxides by a photoredox process in the absence of an external oxidant. The scope of thiazoles and phosphine oxides was further investigated, as was functional group tolerance. The general and operational simplicity provides a novel metal and oxidant-free alternative for the formation of heteroaryl-P bonds, and only molecular hydrogen is generated as a byproduct.

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Silver nitrate-catalyzed cascade decarboxylation and oxidative cyclization of a-oxocarboxylic acids, alkenes, and aldehydes is demonstrated for the first time. With ammonium persulfate as the oxidant, the cascade reactions afford dihydroflavonoid derivatives as products in moderate to good yields, exhibiting a broad substrate tolerance. Control experiments indicated that the mechanism includes a radical pathway with aldehydes as the carbon radical acceptors.

A hydrogenation of N-heterocycles mediated by diboronic acid with water as the hydrogen atom source is reported. A variety of N-heterocycles can be hydrogenated with medium to excellent yields within 10 min. Complete deuterium incorporation from stoichiometric D O onto substrates further exemplifies the H/D atom sources. Mechanism studies reveal that the reduction proceeds with initial 1,2-addition, in which diboronic acid synergistically activates substrates and water via a six-membered ring transition state.