Construction of α-Acyloxy Ketones via Photoredox-Catalyzed O-H Insertion of Sulfoxonium Ylides with Carboxylic Acids

Divergent Synthesis of Dihydrofuran and Dienol Scaffolds via Pd-Catalyzed Decarboxylative Carbene Cross-Coupling

Herein, we report a novel ligand-switchable Pd-catalyzed carbene coupling reaction employing vinylethylene carbonates and sulfoxonium ylides. By proper choice of ligands, the chemoselectivity of the process could be efficiently regulated, allowing for the availability of dihydrofuran or dienol scaffolds. This method features mild reaction conditions, broad scope, and remarkable synthetic utility. Compound 6f can effectively stimulate the secretion of GLP-1, providing promising insight into the development of small-molecule agonists for the GLP-1 receptor.

Palladium-Catalyzed α-Arylation of Sulfoxonium Ylides with Aryl Thianthrenium Salts via C-S and C-H Bond Activation

Diverse α-aryl α-carbonyl sulfoxonium ylides were efficiently synthesized in yields ranging from moderate to high via a palladium-catalyzed α-arylation of sulfoxonium ylides with aryl thianthrenium salts. The reactions proceeded smoothly via C-S and C-H bond functionalization, exhibiting broad substrate scope and good compatibility to various functionalities. In addition, the scale-up synthesis could be achieved, and the one-pot protocol commencing from the use of simple arene as the precursor of aryl thianthrenium salt could also be accomplished.

Palladium-catalyzed α-arylation of sulfoxonium ylides with aryl fluorosulfates

A variety of α-arylated sulfoxonium ylides could be facilely synthesized in modest to high yields through α-arylation of sulfoxonium ylides with aryl fluorosulfates via C-O bond functionalization under palladium catalysis. Reactions using readily available and bench-stable aryl fluorosulfates as effective and appealing arylating agents showed both good substrate scope and broad functionality tolerance. Important functional groups such as nitro, cyano, formyl, acetyl, methoxycarbonyl, trifluoromethoxy, fluoro, and chloro embedded in substrates remained intact during the course of the reaction, and could be subjected to downstream modification. In addition, the reaction could be readily scalable and applied in the late-stage modification of complex molecules.

LiBr-Promoted Reaction of β-Ketodithioesters and Thioamides with Sulfoxonium Ylides to Synthesize Functionalized Thiophenes

An operationally simple and highly efficient synthesis of functionalized thiophenes has been developed by LiBr promoted heteroannulation of β-ketodithioesters and thioamides with bench-stable sulfoxonium ylides in open air for the first time. This one-pot strategy involves formal Csp3-H bond insertion/intramolecular cyclization cascade, featuring readily accessible starting materials, TM and additive-free condition, broad substrate scope, high functional group compatibility, and scalability. Moreover, the carbonyl, thiomethyl, and amino groups in the resulting thiophene provide a good handle on downstream transformations.

Formation of cyclopenta[c]quinolines through visible-light-induced photoredox cascade bis-annulations of 1,7-enynes with sulfoxonium ylides

A novel visible-light-driven photoredox-catalyzed cascade bicyclization of 1,7-enynes with aqueous sulfoxonium ylides is reported. The reaction is highly chemoselective with three new C-C bonds, two new rings, and an all-carbon quaternary stereocenter constructed in a one-pot fashion. This mild protocol features a remarkably broad substrate scope with good functional group tolerance, providing a general and practical approach to access various cyclopenta[c]quinolines.

Synthesis of N-Aryl-4-trifluoromethylthiazol-2-amines via Insertion/Annulation of Trifluoromethylimidoyl Sulfoxonium Ylides with Sodium Thiocyanate

An efficient p-TsOH-mediated insertion of sodium thiocyanate into trifluoromethylimidoyl sulfoxonium ylides has been reported, affording annulated N-aryl-4-trifluoromethylthiazol-2-amines in 42-84% yields in a one-pot manner. This protocol encompasses a variety of trifluoromethylimidoyl sulfoxonium ylides with thiocyanate serving as the source of the "S-C═N" moiety of the thiazole ring. The versatile transformations of the resulting pharmacologically important N-aryl-4-trifluoromethylthiazol-2-amines were also demonstrated.

Stereoselective Three-Component Carbocyclization of 1,7-Enynes with Sulfoxonium Ylides and Water under Photoredox Catalysis

A visible-light-induced photoredox three-component carbocyclization reaction of 1,7-enynes with sulfoxonium ylides and water is reported. The protocol provides a facile entry to structurally valuable highly functionalized cyclopenta[c]quinoline scaffolds in a highly chemoselective and stereoselective manner. Salient features of this method include facile redox-neutral conditions, no requirement of base or other additive, and good functional-group tolerance.

Copper-Mediated Decarboxylative Coupling of 3-Indoleacetic Acids with Sulfoxonium Ylides for the Synthesis of α-Acetoxyl Ketones

The most convenient and direct method of synthesizing an α-acyloxy ketone is the reaction of a diazo compound with a carboxylic acid via O-H insertion. However, due to the limitations in preparing and storing diazo compounds, the application of this method is restricted. In this study, Cu(OAc)2-mediated (OAc = acetate) decarboxylative coupling reactions of 3-indoleacetic acids with sulfoxonium ylides were developed for use in rapidly synthesizing α-acetoxyl ketones. In this reaction, Cu(OAc)2 was not only used as an oxidant, but also as acetate ion source. Notably, when 5-methoxy-2-methyl-3-indoleacetic acid reacted with different sulfoxonium ylides, the corresponding products exhibited fluorescence, and furthermore, several products displayed antiproliferative activities against various human cancer cell lines.

Lithium Bromide-Promoted Formal C(sp3)-H Bond Insertion Reactions of β-Carbonyl Esters with Sulfoxonium Ylides to Synthesize 1,4-Dicarbonyl Compounds

A LiBr-promoted formal C(sp3)-H bond insertion reaction between β-carbonyl esters and sulfoxonium ylides is established. This practical reaction has a wide range of substrate scope for both β-carbonyl esters and sulfoxonium ylides to give a variety of 1,4-dicarbonyl compounds with 43-94% yields. The reaction features transition-metal-free reaction conditions and exclusive C-alkylation chemselectivity. The use of bench-stable sulfoxonium ylides overcomes previous methods that require transition metal as catalysts and unstable diazo compounds or toxic haloketones as alkylation reagents.

Visible light-promoted [3+2] cyclization reaction of vinyl azides with perfluoroalkyl-substituted-imidoyl sulfoxonium ylides

Visible-light-induced [3+2] cyclization of vinyl azides with perfluoroalkyl-substituted imidoyl sulfoxonium ylides has been developed for the first time. In this transformation, perfluoroalkyl-substituted imidoyl sulfoxonium ylides are firstly employed as a carbon radical precursor under visible light irradiation, providing a new and efficient method for the construction of perfluoroalkyl-substituted 1-pyrrolines.

Copper-Mediated Cyclization of Terminal Alkynes with CF3-Imidoyl Sulfoxonium Ylides To Construct 5-Trifluoromethylpyrroles

A copper-mediated [3 + 2] cyclization of CF3-imidoyl sulfoxonium ylides and terminal alkynes has been demonstrated. This work provides a practical approach for assembling 5-trifluoromethylpyrroles with the merits of a broad substrate scope, good functional tolerance, and mild reaction conditions. Control experiments and DFT studies indicate that this reaction may involve the addition of π-bonds of terminal alkynes by copper-carbene radicals and hydrogen migration.

Metal-free synthesis of α-acyloxy ketones from carboxylic acids and sulfoxonium ylides

A straightforward, catalyst- and additive-free approach has been described for synthesizing α-acyloxy ketones from β-ketosulfoxonium ylides and carboxylic acids. Moderate to high yields of α-acyloxy ketones were produced using sulfoxonium ylides and carboxylic acids adorned with various functional groups. Eventually, the applicability of this approach has been shown via a large-scale reaction and transforming the synthesized α-acyloxy ketone derivatives into other valuable compounds.