•Cheap catalytic system and reactants.•One-pot phosgene-free manner.•Phase-transfer catalysis.•Nice recyclability of catalyst selenium.•Broad substrate scope.An efficient, economical, and phosgene-free procedure for the synthesis of N-aryl-N′-2-thiazolylureas is reported. With cheap and recyclable nonmetal selenium instead of noble metals as the catalyst, carbon monoxide instead of virulent phosgene as the carbonylation agent, the selenium-catalyzed carbonylation reaction of 2-aminothiazole can proceed smoothly in one-pot manner with a variety of nitro aromatics in the presence of triethylamine to afford the desired N-aryl-N′-2-thiazolylureas mostly in moderate to good yields. Selenium catalyst can be easily recovered due to its phase-transfer catalytic ability and reused without any significant degradation of its catalytic performance.

In this paper, an efficient synthesis of 5-alkynyl-1,2,3-triazoles through a one-pot aerobic oxidative coupling reaction of various alkynes and azides has been developed. Further derivatization of 5-alkynyl-1,2,3-triazoles readily yielded 5-carbonyl-1,2,3-triazoles, 5-carboxylic-1,2,3-triazole, 5-hydroxyalkyl-1,2,3-triazoles and 5-quinoxaline-1,2,3-triazole, which provided an entry into structurally diverse 5-functionalized-1,2,3-triazoles.In this paper, we report a simple method for the synthesis of 5-alkynyl-1,2,3-triazoles from various alkynes and azides. The transformation of 5-alkynyl-1,2,3-triazoles to structurally diverse 5-functionalized-1,2,3-triazoles via oxidation, reduction and condensation reactions was explored.

An effective synthetic protocol for 5-halo-1,2,3-triazoles was developed by novel TBDMSCl (tert-butyldimethylsilyl chloride)-activated aerobic oxidative halogenations in this Letter. TBDMSCl, for the first time, was found to activate aerobic oxidation of CuX to produce X2 with Cu+ which then could effectively promote one-pot syntheses of 5-halo-1,2,3-triazole from alkyne, azide, and CuX (X = I, Br) under O2 atmosphere at room temperature. The advantages in this method include inexpensive and green O2 as oxidant, use of mild and non-oxidative additive, and wide scope of substrates.An effective three-component assembly of 5-halo-1,2,3-triazoles from alkyne, azide, and CuX was developed by a novel TBDMSCl-activated aerobic oxidative halogenation in this Letter.

Chemoselective reduction of various carbonyl compounds to alcohols with ammonia borane (AB), a nontoxic, environmentally benign, and easily handled reagent, in neat water was achieved in quantitative conversions and high isolated yields. Interestingly, α- and β-keto esters were selectively reduced to corresponding hydroxyl esters by AB, while diols were obtained when sodium borohydride was used as a reducing agent. The procedure is also compatible with the presence of a variety of base-labile protecting groups, such as tosyl, acetyl, benzoyl, ester groups, and acid-labile protecting groups such as trityl and TBDMS groups, and others, such as the unsaturated double bond, nitro and cyano groups. Finally, a kilo scale reaction of methyl benzoylformate with AB was conducted in water and gave methyl mandelate in 94% yield.

Mediated by sodium persulfate (Na2S2O8), a series of polysubstituted 4-pyridones were synthesized via self-condensation of N-aryl acetoacetamides, during which a novel N to C 1,3-acyl migration should be involved. The structure of 4-pyridone was unequivocally confirmed by X-ray diffraction analysis. However, the self-condensation of N-benzyl acetoacetamides under the same condition gave polysubstituted 2-pyridones instead of 4-pyridones.