Copper-Catalyzed Decarboxylative Disulfonylation of Alkynyl Carboxylic Acids with Sulfinic Acids

Palladium(II)-Catalyzed Decarboxylative Difunctionalization of Alkynoic Acids To Access (E)-β-Sulfonylacrylamides and DFT Study

A palladium(II)-catalyzed regio- and stereoselective difunctionalization of alkynoic acids has been achieved using sodium sulfinates and isocyanides to synthesize (E)-β-sulfonylacrylamides. The reaction proceeds via decarboxylative isocyanide addition, followed by sulfonylation. This three-component process works well with aromatic, heteroaromatic, and aliphatic alkynoic acids with good functional group tolerance and excellent regio- and stereoselectivity. DFT calculations were carried out to explain the reaction mechanism and the stereoselective formation of (E)-β-sulfonylacrylamides.

Palladium-catalyzed regioselective decarboxylative hydroarylation of alkynyl carboxylic acids with arylboronic acids

The synthesis of (deuterated) 1,1-disubstituted alkenes via Pd-catalyzed decarboxylative hydroarylation of alkynyl carboxylic acids with arylboronic acids has been developed. The reaction features excellent regioselectivity, a broad substrate scope and gram-scale synthetic ability and offers a general synthetic method to synthesize 1,1-dideuterio olefins. Preliminary mechanism investigations indicate that 1,1-disubstituted alkenes are formed by hydroarylation of terminal alkynes generated by in situ decarboxylation of alkynyl carboxylic acids.

Oxidative Dehydrogenative Coupling of Thiols with Alkanes for the Synthesis of Sulfoxides

An oxidative dehydrogenative coupling of thiols with alkanes via direct C(sp³)-H bond functionalization to form a new C-S bond and S═O double bond was developed. The present reaction features the use of readily available reagents and high step- and atom-efficiency, thus providing an efficient access to sulfoxides. A possible mechanism is proposed.

Visible Light-Induced Highly Regioselective and Stereoselective Oxysulfonylation of Alkynes for the Synthesis of (E)-β-Phenoxy Vinylsulfones

A highly efficient visible light-induced regioselective and stereoselective oxysulfonylation of alkynes with arylsulfonate phenol esters has been developed. This photocatalyst- and metal-free method proceeds smoothly under very mild conditions and exhibits a broad substrate scope, providing (E)-β-phenoxy vinylsulfones in moderate to excellent yields. Mechanistic studies indicated the involvement of an electron donor-acceptor complex-mediated radical process.

The Sulfinylsulfonation of alkynes for β-Sulfinyl alkenylsulfone

Here we report the first example of sulfinylsulfonation of alkynes to afford β-sulfinyl alkenylsulfone products with a broad substrate scope, excellent functional group compatibility, and high yield. Moreover, sulfinylsulfonation reaction of enyne can also be realized for constructing functionalized carbo- and heterocycles through a radical cascade cyclization process.

Temperature Controlled Di- and Monosulfonylation of Propargyl Alcohols with Sodium Sulfinates: Switchable Access to (E)-Allyl, Vinyldisulfones and Propargyl Sulfones

A switchable di- and monosulfonylation of propargyl alcohols with sodium sulfinates is developed, which successfully affords (E)-allyl, vinyldisulfones and propargyl sulfones in good to excellent yields, respectively. The salient features...

Photocatalyzed Coupling-Cyclization of ortho-Alkynylaryl Vinylethers with Arylsulfonyl Azides

A novel visible-light-induced coupling-cyclization of ortho-alkynylaryl vinylethers with arylsulfonyl azides has been described. This transformation provided a concise approach to access C3-exocyclic C═C bond/C2-alkylsulfone-tethered benzofurans via a solvent-leveraged carbosulfonylation and [2 + 2 + 3] cyclization. Primary mechanistic studies demonstrated that THF belongs to a crucial H atom source.

Copper-Catalyzed C-3 Functionalization of Imidazo[1,2-a]pyridines with 3-Indoleacetic Acids

A copper-catalyzed C-3 functionalization of imidazo[1,2-a]pyridines with 3-indoleacetic acids through an aerobic oxidative decarboxylative process has been developed. The protocol provided a series of 3-(1H-indol-3-ylmethyl)-imidazo[1,2-a]pyridines in moderate to good yields under simple reaction conditions. Importantly, some products exhibited potent antiproliferative activity in cancer cell lines.

Decarboxylative Oxyacyloxylation of Propiolic Acids: Construction of Alkynyl-Containing α-Acyloxy Ketones

Novel decarboxylative oxyacyloxylation of propiolic acids has been developed. This reaction provides an efficient access to alkynyl-containing α-acyloxy ketones from readily available starting materials and exhibits significant functional group tolerance. Furthermore, oxyacyloxylation of terminal alkynes and aliphatic propiolic acids was also developed. A possible reaction mechanism is proposed based on mechanistic studies.

Metal-Free Radical Thiocyanatosulfonation of Terminal Alkynes in Aqueous Medium

Here we report a novel and practical approach for preparing (E)-β-(thiocyanato)vinyl sulfones through the 1,2-thiocyanatosulfonation of terminal alkynes with NH₄SCN and sulfonyl hydrazides. Advantages of this reaction include mild conditions, the absence of metal, readily available reagents, a broad substrate scope, good functional group compatibility, and excellent stereoselectivity. The radical species-induced pathway is also demonstrated by mechanistic studies.

Silver-catalyzed synthesis of β-fluorovinylphosphonates by phosphonofluorination of aromatic alkynes

A silver-catalyzed three-component reaction involving alkynes, Selectfluor®, and diethyl phosphite was employed for the one-pot formation of C(sp2)-F and C(sp2)-P bonds to provide an efficient access to β-fluorovinylphosphonates in a highly regio- and stereoselective manner under mild reaction conditions. This reaction is operationally simple and offers an excellent functional group tolerance as well as a broad substrate scope that includes both terminal and internal alkynes. The reaction proceeded through the oxidative generation of a P-centered radical and subsequent fluorine atom transfer.

Disulfonation of terminal alkynes for 1,2-bisulfonylethenes

A highly efficient and operationally simple method for the synthesis of 1,2-disulfonylethenes involving a hypervalent iodineI(iii) reagent to promote disulfonation of terminal alkynes has been developed. This protocol provides a facile and practical pathway to selectively access (E)-1,2-disulfonylethenes that features good functional group compatibility, easily available starting materials, excellent stereoselectivity, and good yields.

Visible light induced 3-position-selective addition of arylpropiolic acids with ethers via C(sp3)-H functionalization

Although the 2-position-selective decarboxylative coupling or addition of arylpropiolic acids with cyclic ethers has been intensively investigated, selective functionalization of arylpropiolic acids at the 3-position is still a big challenge. Herein, an intriguing and mild method for visible light induced regioselective addition of arylpropiolic acids by attacking exclusively at the 3-position with cyclic/acyclic ethers was developed. A variety of 3,3-bis-substituted acrylic acids were successfully obtained in moderate to excellent yields. A plausible reaction mechanism involving an energy transfer induced radical addition in the presence of visible light and photocatalyst was proposed.

Copper-Catalyzed Disulfonation of Terminal Alkynes with Sodium Arylsulfinates

A novel and direct disulfonylation reaction of commercially available terminal alkynes under copper(I)/bromodifluoroacetate cocatalyst has been realized. This protocol provides a facile and practical pathway to selectively access (E)-1,2-disulfonylethenes, in which features good functional group compatibility, easily available starting materials, and excellent stereoselectivity with good yields.

Copper-Catalyzed Decarboxylative Cycloaddition of Propiolic Acids, Azides, and Arylboronic Acids: Construction of Fully Substituted 1,2,3-Triazoles

A copper-catalyzed decarboxylative cycloaddition of propiolic acids, azides, and arylboronic acids is described. The present reaction provides an efficient and convenient method for the synthesis of various fully substituted 1,2,3-triazoles from readily available starting materials. A possible mechanism is proposed.

Oxidative cascade cyclization of 2-cyano-3-arylaniline derived acrylamides with toluenes, ethers, aliphatic alcohols or simple alkanes

Oxidative radical cascade cyclization of 2-cyano-3-arylaniline derived acrylamides with a variety of hydrocarbons including toluenes, ethers, aliphatic alcohols and alkanes has been developed to construct alkyl substituted pyridophenanthridines.

NH2OH-HCl-Mediated Umpolung α-Methylsulfonylation of α-Sulfonyl Ketones with Methylsulfoxides: Synthesis of α,β-Bis-sulfonyl Arylketones

In this paper, a novel and efficient route for the synthesis of α,β-bis-sulfonyl arylketones via an NH₂OH-HCl-mediated intermolecular umpolung α-methylsulfonylation of α-sulfonyl ketones with methylsulfoxides is described. A plausible mechanism is proposed and discussed. Various reaction conditions for this efficient, one-pot, environmentally friendly transformation were investigated.

Metal-Free Radical [2 + 2 + 1] Cyclization of ortho-Cyanoarylacrylamides with Alkyl Nitriles: Synthesis of Pyrrolo[3,2- c]quinolines

A novel radical [2 + 2 + 1] cyclization of ortho-cyanoarylacrylamides with dual α-C-H bonds in alkyl nitriles has been developed. The reaction provides new facile and straightforward access to cyano-substituted pyrrolo[3,2- c]quinolines, which are important nitrogen-containing polyheterocycles. A possible mechanism for the transformation is proposed.

Decarboxylative cascade cyclization of α-keto acids with 2-cyano-3-arylaniline-derived acrylamides

An oxidative decarboxylative cascade cyclization of α-keto acids with 2-cyano-3-arylaniline-derived acrylamides delivering carbonyl-containing pyrido[4,3,2-gh]phenanthridines is presented.

Metal-Free Synthesis of Functionalized Tetrasubstituted Alkenes by Three-Component Reaction of Alkynes, Iodine, and Sodium Sulfinates

An operationally simple, efficient, and metal-/peroxide-free three-component reaction of alkynes, iodine, and sodium sulfinates has been developed for the construction of highly functionalized tetrasubstituted alkenes. Iodo- and sulfonyl-containing tetrasubstituted alkenes, such as vinyl ketones, allylic alcohols, and conjugated enynes, could be obtained regio- and stereoselectively in up to 96% yield.