Gaoqing Yuan

Copper-catalyzed aerobic oxidation and cleavage/formation of C–S bond: a novel synthesis of aryl methyl sulfones from aryl halides and DMSO

With atmospheric oxygen as the oxidant, a novel copper(I)-catalyzed synthesis of aryl methyl sulfones from aryl halides and widely available DMSO is described. The procedure tolerates aryl halides with various functional groups (such as methoxy, acetyl, chloro, fluoro and nitro groups), which could afford aryl methyl sulfones in moderate to high yields. The copper-catalyzed aerobic oxidation and the cleavage/formation of C-S bond are the key steps for this transformation.

NH4I-mediated three-component coupling reaction: metal-free synthesis of β-alkoxy methyl sulfides from DMSO, alcohols, and styrenes.

A novel synthesis recipe for β-alkoxy methyl sulfides was developed via NH4I-mediated three-component oxysulfenylation reaction of styrenes with DMSO and alcohols. This method features simple operation and readily available starting materials, and it provides an alternative sulfenylating agent generated from DMSO for oxysulfenylation reactions.

Nano‐Cu2O‐Catalyzed Formation of CC and CO Bonds: One‐Pot Domino Process for Regioselective Synthesis of α‐Carbonyl Furans from Electron‐Deficient Alkynes and 2‐Yn‐1‐ols

The formation of carbon-carbon and carbon-oxygen bonds continues to be an active and challenging field of chemical research. Nanoparticle catalysis has attracted considerable attention owing to its environmentally benign and high activity toward the reactions. Herein, we described a novel and effective nano-Cu(2)O-catalyzed one-pot domino process for the regioselective synthesis of α-carbonyl furans. Various electron-deficient alkynes with 2-yn-1-ols underwent this process smoothly in moderate to good yields in the presence of air at atmospheric pressure. It is especially noteworthy that a novel 2,4,5-trisubstituted 3-ynylfuran was formed in an extremely direct manner without tedious stepwise synthesis. Additionally, as all of the starting materials are readily available, this method may allow the synthesis of more complex α-carbonyl furans. An experiment to elucidate the mechanism suggested that the process involved a carbene intermediate.

Synthesis of sulfonamides via I2-mediated reaction of sodium sulfinates with amines in an aqueous medium at room temperature

An efficient I2-mediated approach for the synthesis of sulfonamides at room temperature using water as the solvent has been developed. This method for the synthesis of sulfonamides is quite convenient and environmentally friendly. In addition, the purification procedure of the desired products becomes very easy.

Carbon Dioxide Triggered and Copper-Catalyzed Domino Reaction: Efficient Construction of Highly Substituted 3(2H)-Furanones from Nitriles and Propargylic Alcohols

A novel carbon dioxide triggered and copper-catalyzed domino reaction for the efficient synthesis of highly substituted 3(2H)-furanones from readily available nitriles and propargylic alcohols has been developed. Carbon dioxide is a prerequisite for achieving the present catalytic transformation, and one of the oxygen atoms of carbon dioxide is incorporated into the 3(2H)-furanones. Nitriles not only act as the reaction solvent but also as the reactant; copper salts play dual roles of activating both the propargylic alcohols and nitriles.

Iodine-mediated synthesis of (E)-vinyl sulfones from sodium sulfinates and cinnamic acids in aqueous medium

With water as the reaction medium, a green and efficient method has been developed for the synthesis of (E)-vinyl sulfones via I2-mediated decarboxylative cross-coupling reactions of sodium sulfinates with cinnamic acids. This synthetic route could effectively avoid the use of toxic organic solvents and transition metal catalysts, and the target products could be obtained with moderate to excellent yields under green and mild conditions.

Ammonium iodide-promoted cyclization of ketones with DMSO and ammonium acetate for synthesis of substituted pyridines

A simple and efficient method has been developed for the synthesis of symmetrical and unsymmetrical pyridines via NH4I-promoted cyclization of ketones with DMSO and NH4OAc. It was found that methyl ketones always gave selective formation of the unsymmetrical pyridine, while non-methyl ketones gave unpredictable results (symmetrical or non-symmetrical product only, or a mixture of the two). In addition, the deuterium-labeling experiments indicated that the C4 or C6 of the target product pyridine rings resulted from DMSO.

I2/TBHP Mediated C–N and C–H Bond Cleavage of Tertiary Amines toward Selective Synthesis of Sulfonamides and β-Arylsulfonyl Enamines: The Solvent Effect on Reaction

A novel method toward synthesis of sulfonamides and β-arylsulfonyl enamines has been developed via I2/TBHP mediated C-N and C-H bond cleavage of tertiary amines, which features highly selective formation of two different target products depending on the reaction solvent. The experimental results reveal that H2O as the solvent could effectively achieve the C-N bond cleavage to produce sulfonamides due to H2O participating in the reaction process where H2O plays a dual role. Differing from H2O, organic solvents (such as dimethyl sulfoxide) could promote the C-H bond cleavage of tertiary amines to yield β-arylsulfonyl enamines.

Electrochemically promoted synthesis of polysubstituted oxazoles from β-diketone derivatives and benzylamines under mild conditions

An efficient electrochemical synthesis of poly-substituted oxazoles from readily available β-diketone derivatives and benzylamines is described. This electrochemical procedure does not need hazardous oxidants and transition metal catalysts as well as molecular I2 additives. Compared with the traditional thermo-chemical method, the present electrochemical method is greener and more efficient.

Morphology-controllable electrochemical synthesis and photoluminescence properties of ZnO nanocrystals with porous structures

A modified electrochemical route was developed to deposit powdery ZnO nanocrystals. The approach is based on sodium citrate acting as the supporting electrolyte as well as a complex agent, Zn2+ ions resulting from the electro-oxidation of a Zn anode rather than zinc salts, and a H2O–EtOH mixed-solvent as the electrolytic medium. The supporting electrolytes, electrolytic media and additives play important roles in controlling the morphology of ZnO crystals. Under the synergetic action of the complex effect of citrate ions and solvent effect of H2O–EtOH (or electrostatic-adsorption of additives), ZnO nanoparticles could self-assemble to the nanocrystals with porous structures (such as nanospheres, nanoflowers and coral-like nanocrystals) without templates. The morphology of the ZnO crystals could evolve from nanospheres to nanorods or nanospindles by changing the electrolytic media or supporting electrolytes. A possible growth mechanism of the ZnO nanocrystals with different shapes was also discussed. In addition, further studies indicate that the prepared nanospheres (or nanoflowers) with hollow or porous structures have better photoluminescence performances than the nanorods.