Organophosphorus compounds have attracted continuous attention in materials science, agrochemical and pharmaceutical fields due to their unique bioactivities. Thus, the development of novel and robust manners for the construction new C P bond has therefore gained great interests in synthetic organic chemistry. Because of their intrinsic sustainability and green chemistry character, visible light-induced photoredox catalysis has been widely applied in the construction of new chemical bonds, including the formation of C P bond. In this review, we summarized recent achievements in C P bond formation reactions initiated by visible light-induced photoredox catalysis, which mainly focusing on the discussion of reaction design and the mechanism.

Visible light-mediated C P bond formation reactions

Visible light promoted cross-dehydrogenative coupling: a decade update

2-Propargyl Alcohols in Organic Synthesis

A novel enantioselective aminomethylation reaction of diazo compound, alcohol and α-aminomethyl ether enabled by asymmetric counteranion-directed catalysis is disclosed that offers an efficient and convenient access to furnish optically active α-hydroxyl-β-amino acids in high yield with high to excellent enantioselectivities. Control experiments and DFT calculations indicate that the transformation proceeds through trapping the in situ generated enol intermediate with methylene iminium ion, and the asymmetric induction was enabled by chiral pentacarboxycyclopentadiene anion via H-bonding and electrostatic interaction.

Asymmetric Counter-Anion-Directed Aminomethylation: Synthesis of Chiral β-Amino Acids via Trapping of an Enol Intermediate.

Herein, we report a greener protocol for the synthesis of 3-Se/S-indoles and imidazo[1,2-a]pyridines through direct C(sp2 )-H bond chalcogenation of heteroarenes with half molar equivalents of different dichalcogenides, using KIO3 as a non-toxic, easy-to-handle catalyst and a stoichiometric amount of glycerol. The reaction features are high yields, based on atom economy, easy performance on gram-scale, metal- and solvent-free conditions as well as applicability to different types of N-heteroarenes.

Direct, Metal-free C(sp2 )-H Chalcogenation of Indoles and Imidazopyridines with Dichalcogenides Catalysed by KIO3.

A metal-free visible-light-induced phosphonylation of 2H-indazoles with diphenylphosphine oxide has been developed using rose bengal as an organophotoredox catalyst under ambient air at room temperature. A library of diphenyl(2-phenyl-2H-indazol-3-yl)phosphine oxide with broad functionalities has been synthesized in high yields. The experimental result suggests the radical pathway of the reaction.

Visible-Light-Induced Organophotoredox-Catalyzed Phosphonylation of 2H-Indazoles with Diphenylphosphine Oxide

A visible-light-promoted regioselective C(sp2)-H/C(sp3)-H cross-dehydrogenative coupling between 2 H-indazoles and ethers has been achieved using a catalytic amount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature under aerobic conditions. A variety of C-3 oxyalkylated 2 H-indazoles have been synthesized in moderate to good yields. Mechanistic studies suggest a radical pathway of the present reaction.

Visible-Light-Induced Regioselective Cross-Dehydrogenative Coupling of 2 H-Indazoles with Ethers.

Aminomethylation of Imidazoheterocycles with Morpholine.

Organophotoredox-Catalyzed C(sp2)-H Difluoromethylenephosphonation of Imidazoheterocycles.

A Zn(OTf)2-catalyzed simple and efficient method has been developed for the synthesis of imidazole-substituted allenes by the reaction of 1,1,3-triphenylprop-2-yn-1-ol and imidazoheterocycles. A library of tetrasubstituted allenes with broad functionalities have been prepared with excellent yields. The present methodology is also applicable to imidazo[1,2-a]pyrimidine, imidazo[2,1-b]thiazole and benzo[d]imidazo[2,1-b]thiazole.

Mukta Singsardar

Papers

Visible-Light-Induced Organophotoredox-Catalyzed Phosphonylation of 2H-Indazoles with Diphenylphosphine Oxide

Visible-Light-Induced Regioselective Cross-Dehydrogenative Coupling of 2 H-Indazoles with Ethers.

Aminomethylation of Imidazoheterocycles with Morpholine.

Organophotoredox-Catalyzed C(sp2)-H Difluoromethylenephosphonation of Imidazoheterocycles.

Zn(OTf)2-Catalyzed Synthesis of Imidazole-Substituted Allenes