Photoinduced Alkylsulfonylation and Cyanoalkylsulfonylation of Morita-Baylis-Hillman Adducts via Multicomponent Insertion of Sulfur Dioxide

General and convenient visible-light-promoted alkylsulfonylation and cyanoalkylsulfonylation of MBH adducts have been developed through the multicomponent insertion of sulfur dioxide, enabling the assembly of two C-S bonds to generate structurally diverse allylic alkylsulfones (43 examples in total). The reaction of MBH adducts with potassium alkyltrifluoroborates and 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct afforded sulfones with generally good yields. Notably, the addition of N,N,N',N'-tetramethylethylenediamine as a base into the photocatalytic system led to yielding an alkyl sulfonyl unit and cyano group-anchored trisubstituted alkenes by utilizing cycloketone oxime esters as C-radical precursors. Both of these reactions have constructed two C-S bonds, and all desired products were obtained in moderate to excellent yields with complete stereospecificity.

Copper Catalyst-Promoted Regioselective Multicomponent Cascade Cyclization of 3-Aza-1,5-enynes with Sulfur Dioxide and Cycloketone Oxime Esters to Access Cyanoalkylsulfonylated 1,2-Dihydropyridines

Radical cascade cyclization via the cracking of alkenyl C-H has emerged as an attractive and remarkable tool for the rapid construction of ring frameworks with endocyclic double bonds. We developed a cascade reaction of 3-aza-1,5-enynes with sulfur dioxide and cycloketone oxime esters to access cyanoalkylsulfonylated 1,2-dihydropyridines, which can be easily converted to pyridine derivatives. This protocol involves radical addition to the C≡C bond and 6-endo cyclization and features high regioselectivity and a broad substrate scope.

Visible-Light-Promoted Cyanoalkylation/Cyclization Cascade Reaction to Assemble Polyheterocycles in Continuous Flow

This study describes a visible-light-induced cascade reaction for preparing cyanoalkyl-containing polyheterocycles initiated by the photoinduced radical cascade addition of N-arylacrylamide derivatives using cyclic oxime esters as radical sources followed by cyanoalkyl-mediated cyclization. This protocol features outstanding functional group compatibility, providing a variety of desired phenanthridine derivatives in moderate to good yields. Moreover, the application of a microflow technique enhanced these reactions compared with the equivalent batch reaction, significantly reducing reaction times to 10 min.

Difunctionalization of Dienes, Enynes and Related Compounds via Sequential Radical Addition and Cyclization Reactions

Radical reactions are powerful in creating carbon-carbon and carbon-heteroatom bonds. Designing one-pot radical reactions with cascade transformations to assemble the cyclic skeletons with two new functional groups is both synthetically and operationally efficient. Summarized in this paper is the recent development of reactions involving radical addition and cyclization of dienes, diynes, enynes, as well as arene-bridged and arene-terminated compounds for the preparation of difunctionalization cyclic compounds. Reactions carried out with radical initiators, transition metal-catalysis, photoredox, and electrochemical conditions are included.

Photoredox-catalyzed intermolecular azidosulfonylation of alkenes with DABCO·(SO2)2, trimethylsilyl azide and thianthrenium salts

Synthesis of β-azido alkylsulfones through a photoredox-catalyzed azido sulfonylation of alkenes with DABCO·(SO2)2, trimethylsilyl azide and alkyl thianthrenium salts is developed.

Synthesis of Selenyl-Substituted Quinoline Derivatives via Substrate-Controlled Three-Component Domino Reactions

A simple and efficient method for the preparation of selenyl-substituted quinoline derivatives through a CSp3-H selenylation of in situ-generated 3-acetyl quinoline has been developed. This protocol is easy to handle, scalable, and good functional group tolerant, providing a rapid method to 3-selenoacetyl quinoline and 3-diselenoacetyl quinoline derivatives.

Photoredox-Catalyzed α-Sulfonylation of Ketones from Sulfur Dioxide and Thianthrenium Salts

A photoredox-catalyzed sulfonylation of silyl enol ethers with DABCO·(SO₂)₂ and thianthrenium salts is achieved, providing diverse β-keto sulfones in moderate to good yields. This protocol features easily accessible starting materials and good functional group compatibility, enabling the introduction of various functionalized sulfonyl groups into ketones. Furthermore, as one of the important industrial raw materials, methanol can be employed as the methyl source to prepare α-methylsulfonated ketones through a methyl thianthrenium intermediate for the first time.

Visible-Light-Mediated Three-Component Radical Iodosulfonylative Cyclization of Enynes

An efficient three-component radical iodosulfonylative cyclization of enynes is described. The visible-light irradiation of iodoform with sulfinates enables sulfonyl radical generation under catalyst- and oxidant-free conditions and triggers the radical addition, cyclization and iodination cascade reactions, giving various vinyl iodide containing sulfones in moderate to good yields.

Palladium-catalyzed radical cascade cyanoalkylsulfonylation/cyclization of 3-arylethynyl-[1,1'-biphenyl]-2-carbonitriles with cyclobutanone oxime esters and DABSO

A palladium-catalyzed radical cascade cyanoalkylsulfonylation/cyclization of 3-arylethynyl-[1,1'-biphenyl]-2-carbonitriles with DABCO·(SO₂)₂ and cyclobutanone oxime esters via cleavage of a C-C single bond and insertion of SO₂ was described. A series of cyanoalkylsulfone-containing cyclopenta[gh]phenanthridines were obtained in moderate-to-good yields, thus featuring mild reaction conditions, a broad substrate scope, and a high functional group tolerance.

An iron-catalyzed multicomponent reaction of cycloketone oxime esters, alkenes, DABCO·(SO2)2 and trimethylsilyl azide

The synthesis of β-azidosulfones starting from alkenes, cycloketone oxime esters, trimethylsilyl azide and a sulfur dioxide surrogate of DABCO·(SO2)2 under iron catalysis is developed.

Direct selenosulfonylation of unsaturated compounds: a review

In this review, we have discussed recent developments on the direct selenosulfonylation of unsaturated compounds which lead to the formation of two new carbon-sulfur and carbon-selenium bonds in a single operation. The reactions were classified based on the type of starting unsaturated compound and product. Thus, the review is divided into three major sections. The first describes the current literature on selenosulfonylation of alkenes. The second section covers the available literature on selenosulfonylation of alkynes. The third focuses exclusively on selenosulfonylation of allenes.

In this review, we have discussed recent developments on the direct selenosulfonylation of unsaturated compounds which lead to the formation of two new carbon-sulfur and carbon-selenium bonds in a single operation.

Construction of sulfonated spiro[5,5]trienones from sulfur dioxide via iron-catalyzed dearomative spirocyclization of biaryls

An iron-catalyzed dearomative spirocyclization of biaryl ynones with sodium metabisulfite and cycloketone oxime esters is developed. By using sodium metabisulfite as the source of sulfur dioxide, this approach enables the...

Synthesis of β-cyanoalkylsulfonylated vinyl selenides through a four-component reaction

A mild copper-catalyzed four-component selenosulfonylation of alkynes, cycloketone oxime esters, DABCO (SO₂)₂ and diselenides has been developed. This method enables the rapid assembly of β-cyanoalkylsulfonylated vinyl selenides in moderate to good yields. Advantages of this protocol include a broad substrate scope, good functional group tolerance and the late-stage functionalization of complex molecules. Moreover, the potential utility of this methodology is demonstrated through simple oxidation of the products to access synthetically important alkynyl sulfones. Mechanistic studies suggest that a cyanoalkylsulfonyl radical intermediate is involved in this process.