Daoshan Yang

Copper-catalyzed synthesis of benzimidazoles via cascade reactions of o-haloacetanilide derivatives with amidine hydrochlorides

We have developed an efficient method for the synthesis of benzimidazoles via cascade reactions of o-haloacetoanilide derivatives with amidine hydrochlorides. The protocol uses 10 mol % CuBr as the catalyst, Cs2CO3 as the base, and DMSO as the solvent, and no ligand is required. The procedure proceeds via the sequential coupling of o-haloacetoanilide derivatives with amidines, hydrolysis of the intermediates (amides), and intramolecular cyclization with the loss of NH3 to give 2-substituted 1H-benzimidazoles.

Catalyst-free direct arylsulfonylation of N-arylacrylamides with sulfinic acids: a convenient and efficient route to sulfonated oxindoles

A simple, efficient and catalyst-free procedure has been developed for the construction of sulfonated oxindoles via the direct arylsulfonylation of N-arylacrylamides with sulfinic acids. The present protocol, which simply utilizes cheap oxidants, readily-available starting materials, and catalyst-free conditions, provides an alternative and highly attractive approach to a series of sulfonated oxindoles with high atom efficiency and excellent functional group tolerance.

Silver-Mediated Radical Cyclization of Alkynoates and α-Keto Acids Leading to Coumarins via Cascade Double C–C Bond Formation

A novel and convenient silver-mediated radical cyclization method for the synthesis of coumarin derivatives via the direct difunctionalization of alkynoates with α-keto acids through double C-C bond formation under mild conditions has been developed. This new method is highly efficient and practical, and the starting materials are readily prepared. The present method should provide a useful strategy for the construction of coumarin motifs.

Catalyst-Free Regioselective C-3 Thiocyanation of Imidazopyridines

A direct and straightforward approach for highly regioselective thiocyanation of imidazoheterocycles through sp(2) C-H functionalization has been realized at room temperature. Various C-3 thiocyanated imidazopyridines are formed in moderate to good yield. The present method exhibits a mild and selective access to a variety of imidazopyridine derivatives of pharmacological interest.

Metal-Free Oxidative Spirocyclization of Alkynes with Sulfonylhydrazides Leading to 3-Sulfonated Azaspiro[4,5]trienones

A novel and direct oxidative spirocyclization of arylpropiolamides with sulfonylhydrazides leading to 3-sulfonated azaspiro[4,5]trienones has been developed under metal-free conditions. The reaction is performed in a tandem manner constituted by the sequential sulfonylation of alkynes, ipso-carbocyclization, dearomatization, hydration, and oxidation processes, providing a convenient and efficient approach to various sulfonated azaspiro[4,5] trienones of biological importance.

Efficient copper-catalyzed N-arylations of nitrogen-containing heterocycles and aliphatic amines in water

A simple and efficient copper-catalyzed method has been developed for N-arylations of nitrogen-containing heterocycles and aliphatic amines in water. The protocol uses (1E,2E)-oxalaldehyde dioxime (OADO) as the ligand, and water as the solvent, and shows good tolerance towards various functional groups.

Metal-Free Iodine-Catalyzed Direct Arylthiation of Substituted Anilines with Thiols

Iodine-catalyzed direct arylthiation of substituted anilines for the synthesis of various diaryl sulfides has been developed under metal- and solvent-free conditions. The present method uses readily available thiols as the arylthiation reagents, and environmentally friendly and inexpensive I2 as the catalyst. Importantly, no base or ligand was necessary. Such a simple, efficient, and economical transformation provides an attractive approach to various diaryl sulfides in good to excellent yields.

Direct difunctionalization of alkynes with sulfinic acids and molecular iodine: a simple and convenient approach to (E)-β-iodovinyl sulfones

A simple and convenient approach for the construction of β-iodovinyl sulfones has been developed via direct difunctionalization of alkynes with sulfinic acids and molecular iodine. The present reaction provides a highly efficient approach to a diverse range of substituted (E)-β-iodovinyl sulfones in moderate to good yields with excellent stereo- and regio-selectivities but no need for any metal catalyst or additives.

Visible-light initiated direct oxysulfonylation of alkenes with sulfinic acids leading to β-ketosulfones

Visible light along with 1 mol% eosin Y catalyzed the direct oxysulfonylation of alkenes with sulfinic acids via a photoredox process which has been developed at room temperature under transition-metal-free conditions. The present reaction provides a highly efficient approach to diverse β-ketosulfones in moderate to good yields. It should provide a promising synthesis candidate for the formation of diverse and useful β-ketosulfone derivatives in the fields of synthetic and pharmaceutical chemistry.

Molecular Iodine-Mediated Difunctionalization of Alkenes with Nitriles and Thiols Leading to β-Acetamido Sulfides

A direct difunctionalization protocol of alkenes with nitriles and thiols toward β-acetamido sulfide derivatives has been proposed under metal-free synthesis conditions. The present protocol provides the facile and highly efficient synthesis of various β-acetamido sulfides in a scaled-up manner with good to excellent yields simply using inexpensive molecular iodine as a catalyst, DMSO as a mild oxidant, and readily available thiols as thiolating reagents.