Iron-catalyzed dual decarboxylative coupling of α-amino acids and dioxazolones under visible-light to access amide derivatives.

A facile and efficient thiol-free one-pot method for direct synthesis of sulfides and sulfoxides under green conditions without using any metal catalyst is reported. For this purpose, we used benzyl bromides as starting materials in the presence of potassium thioacetate (PTA) and Oxone® which are low-cost, and readily accessible chemicals. This method is highly compatible with a variety of functional groups and delivered a series of sulfides, bis-sulfides, and sulfoxides in good yields. The selective formation of sulfoxides over sulfones is discussed via a mechanism.

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One-pot thiol-free synthetic approach to sulfides, and sulfoxides selectively

Dual photoredox- and nickel-catalyzed hydroalkylation of terminal alkynes with 4-alkyl-1,4-dihydropyridines under visible light irradiation to afford Markovnikov- or anti -Markovnikov-type alkylated alkenes in good to high yields has been achieved, where regioselectivity of the products has been effectively controlled by coordination ligands for nickel species. Use of [NiCl 2 (dtbbpy)] as a catalyst has led to the formation of Markovnikov-type products, whereas that of NiCl 2 ·6H 2 O has led to the formation of anti -Markovnikov- type products.

Photoredox- and Nickel-Catalyzed Hydroalkylation of Alkynes with 4-Alkyl-1,4-dihydropyridines: Ligand-Controlled Regioselectivity.

[reaction: see text] We report a method for the synthesis of vinyl sulfides using the soluble copper(I) catalyst [Cu(phen)(PPh3)2]NO3. The desired vinyl sulfides are obtained in good to excellent yields, with retention of stereochemistry. This protocol tolerates a wide variety of functional groups or substrates, is palladium-free, and does not require the use of expensive or air-sensitive additives.

Copper-catalyzed synthesis of vinyl sulfides.

Recent Progress in Photoinduced Iron-catalyzed Coupling Reactions

Herein, we disclose a protocol to synthesize trisubstituted alkenyl thioethers through a direct S-alkylation of 1,2,3-thiadiazoles with C-radical precursors, 4-alkyl-1,4-dihydropyridines (DHPs), driven by visible-light photocatalysis. A broad range of primary, secondary, and tertiary C-radical precursors, DHPs, are suitable for this reaction and the desired products can be obtained in good to excellent yields under mild conditions. Remarkably, high stereoselectivity with Z-alkenyl thioethers was achieved in the presence of a Cu(OAc)2 catalyst. Synergistic experimental and computational studies were carried out to shed light on the mechanisms of this reaction, in which the quenching pathway of an excited photocatalyst (*RuII) could be altered in the presence of the Cu(OAc)2 catalyst. A reductive quenching pathway (RuII/*RuII/RuI/RuII) is proposed in the absence of the Cu(OAc)2 catalyst while an oxidative quenching pathway (RuII/*RuII/RuIII/RuII) is suggested with the assistance of the Cu(OAc)2 catalyst. In addition, the origin of the Z-selectivity of the product is discussed.

Zhanqun Liang

Papers

Visible-light photocatalytic preparation of alkenyl thioethers from 1,2,3-thiadiazoles and Hantzsch esters: synthetic and mechanistic investigations

Iron-catalyzed dual decarboxylative coupling of α-amino acids and dioxazolones under visible-light to access amide derivatives.