Guanyinsheng Qiu

Copper-Catalyzed Direct Trifluoromethylation of Propiolates: Construction of Trifluoromethylated Coumarins

A novel copper-catalyzed direct trifluoromethylation of internal alkynes was developed, obtaining a series of trifluoromethylated coumarins in good yields. The cyclization was proposed to proceed via a radical mechanism under copper-catalyzed conditions with good functional group tolerance.

Multicatalytic one-pot reaction of 1-(2-alkynylphenyl)ketoximes for generation of indole derivatives.

Multicatalytic one-pot Beckmann rearrangement/intramolecular cyclization/halogenation reaction of 1-(2-alkynylphenyl)ketoxime is reported, leading to the expected indole derivatives in good yield.

Recent developments for the photoinduced Ar–X bond dissociation reaction

Recent developments in the photochemical carbon–carbon and carbon–heteroatom bond formation via photoinduced Ar–X bond dissociation are summarized. The transformations through the Ar–X bond dissociation enabled by photoenergy include nucleophilic substitution, arylation, alkylation, aminocarbonylation, aminosulfonylation and decarboxylative coupling reactions. Usually, the reactions undergo one-electron-transfer couplings and aryl radicals or cations are involved as the key intermediates. Under ultraviolet irradiation or visible light, the reactions of aryl halides with reactive partners proceed smoothly under mild conditions. In some cases, the transformations can proceed without any metals or photo-redox catalysts. Moreover, the broad reaction scope is demonstrated with good functional group tolerance.

Generation of 1-(trifluoromethyl)isoquinolines via a copper-catalyzed reaction of isoquinoline-N-oxide with Togni reagent

Isoquinoline-N-oxides react with Togni reagent catalyzed by copper(II) triflate, leading to 1-(trifluoromethyl)isoquinolines in good yields. The reaction proceeds smoothly under mild conditions with high efficiency.

Generation of 1-amino-isoquinoline-N-oxides via a tandem reaction of 2-alkynylbenzaldoxime with secondary amines in the presence of silver(I) and copper(I)

1-Amino-isoquinoline-N-oxides are generated under mild conditions through a tandem reaction of 2-alkynylbenzaldoxime with secondary amines in the presence of silver(I) and copper(I). The reaction proceeds smoothly at room temperature under air, leading to the corresponding products in good yields. During the reaction process, a silver-catalyzed 6-endo cyclization and a copper(I)-catalyzed C–H bond activation are involved.

Reaction of N′-(2-alkynylbenzylidene)hydrazide with tertiary amine: a concise synthesis of H-pyrazolo[5,1-a]isoquinolines

The reaction of N′-(2-alkynylbenzylidene)hydrazide with tertiary amine via C–H bond activation in the presence of cooperative catalysis was reported, which generates H-pyrazolo[5,1-a]isoquinolines in good yields under mild conditions.

Synthesis of 6-(sulfonylmethyl)phenanthridines through a reaction of aryldiazonium tetrafluoroborates, sulfur dioxide, and vinyl azides

Synthesis of 6-(sulfonylmethyl)phenanthridines through a three-component reaction of aryldiazonium tetrafluoroborates, a sulfur dioxide surrogate of DABCO·(SO2)2, and vinyl azides under metal- and additive-free conditions is achieved. The arylsulfonyl radicals generated in situ would initiate the sulfonylation of vinyl azides. Subsequent intramolecular cyclization and deprotonation would provide 6-(sulfonylmethyl)phenanthridines in good yields. High efficiency under extremely mild conditions with the insertion of sulfur dioxide through a radical process is observed.

Striving to exploit alkyl electrophiles: challenge and choice in transition metal-catalyzed cross-coupling reactions of sulfones

For cross-coupling reactions of alkyl electrophiles, alkyl halides, alkyl tosylates, alkyl acetates and alkyl sulfones exhibit high reaction efficiency when various transition metal catalysts and reaction partners are employed. As crystalline and readily available alkyl electrophiles, alkyl sulfones in radical cross-coupling reactions open a new avenue for modularly generating diverse alkyl compounds. It is believed that more transformations using sulfones as electrophiles will be developed in the near future.