Laijin Tian

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.

Silver-catalyzed double-decarboxylative cross-coupling of α-keto acids with cinnamic acids in water: a strategy for the preparation of chalcones.

A silver-catalyzed double-decarboxylative protocol has been proposed for the construction of chalcone derivatives via cascade coupling of substituted α-keto acids with cinnamic acids under the mild aqueous conditions. The developed method for constructing C-C bonds via double-decarboxylative reactions is efficient, practical, and environmentally benign by using the readily available starting materials. It should provide a promising synthesis candidate for the formation of diverse and useful chalcone derivatives in the fields of synthetic and pharmaceutical chemistry.

Metal-free n-Et4NBr-catalyzed radical cyclization of disulfides and alkynes leading to benzothiophenes under mild conditions

A novel n-Et4NBr-catalyzed method for the synthesis of benzothiophene derivatives via cascade reactions of substituted disulfides with alkynes through S–S bond cleavage and alkenyl radical cyclization reactions has been developed. The reaction has a high functional-group tolerance. The new method is environmental and practical, and the starting materials are readily available. These advantages, relative to previous methods, provide an opportunity for the construction of diverse and useful benzothiophene motifs.

Copper-catalyzed cyanoalkylarylation of activated alkenes with AIBN: a convenient and efficient approach to cyano-containing oxindoles

A novel, simple, and cost-effective copper-catalyzed direct cyanoalkylarylation of activated alkenes with AIBN has been developed with cheap K2S2O8 as the oxidant. A series of cyano-containing oxindoles that are otherwise difficult to obtain through previous methods were efficiently synthesized using this protocol.

Copper-Catalyzed Domino Synthesis of Nitrogen Heterocycle-Fused Benzoimidazole and 1,2,4-Benzothiadiazine 1,1-Dioxide Derivatives

A convenient copper-catalyzed domino method for the synthesis of nitrogen heterocycle-fused benzoimidazole and 1,2,4-benzothiadiazine 1,1-dioxides has been developed using readily available 2-bromo-N-phenylbenzenesulfonamides and benzimidazole derivatives as the starting materials. The domino process comprises an Ullmann-type N-arylation and intramolecular C-H amination. The inexpensive and efficient copper-catalyzed method should provide a new and useful strategy for for constructing novel, biologically interesting heterocycles containing benzoimidazole and 1,2,4-benzothiadiazine 1,1-dioxide motifs.

Copper-catalyzed decarboxylative stereospecific amidation of cinnamic acids with N-fluorobenzenesulfonimide

An efficient copper-catalyzed decarboxylative coupling of cinnamic acids with N-fluorobenzenesulfonimide (NFSI) to give the corresponding substituted (E)-amination products stereospecifically is demonstrated. This new method is efficient and practical, and the corresponding products were obtained in moderate to good yields. The present protocol should broaden the scope of the decarboxylative cross-coupling reactions and provide a useful strategy for the construction of C–N bonds.

Metal-free TBHP-mediated oxidative ring openings of 2-arylimidazopyridines via regioselective cleavage of C-C and C-N bonds†

A highly regioselective TBHP-mediated ring opening of imidazopyridines via cleavage of C–C and C–N bonds has been achieved for the first time to afford N-(pyridin-2-yl)benzamides. Preliminary mechanistic investigations revealed that the present metal-free transformation involved a radical pathway, and the oxygen atom incorporated in the end products might derive from TBHP.