Copper-catalyzed C-H ethoxycarbonyldifluoromethylation of imidazoheterocycles.

A regioselective copper-catalyzed ethoxycarbonyl-difluoromethylation of imidazo[1,2-a]pyridines has been developed through sp(2) C-H bond functionalization with BrCF2CO2Et under ambient air. A series of ethoxycarbonyldifluoromethylated imidazo[1,2-a]pyridines with broad functionalities have been synthesized. This methodology is also applicable to imidazo[2,1-b]thiazole and benzo[d]imidazo[2,1-b]thiazole.

Metal-Free Thiocyanation of Imidazoheterocycles through Visible Light Photoredox Catalysis.

A visible light mediated, metal-free process for the thiocyanation of imidazoheterocycles has been developed using eosin Y as a photoredox catalyst under ambient air at room temperature. A library of 3-(thiocyanato)imidazo[1,2-a]pyridines with broad functionalities have been synthesized in high yields. This methodology is also applicable for the selenocyanation of imidazo[1,2-a]pyridine.

Regioselective Synthesis of Multisubstituted Furans via Copper-Mediated Coupling between Ketones and β-Nitrostyrenes.

A copper-mediated intermolecular annulation of alkyl ketones and β-nitrostyrenes has been developed for the regioselective synthesis of multisubstituted furan derivatives in good yields. This protocol is applicable to both cyclic and acyclic ketones.

FeCl3/ZnI2-catalyzed synthesis of benzo[d]imidazo[2,1-b]thiazole through aerobic oxidative cyclization between 2-aminobenzothiazole and ketone.

The FeCl3/ZnI2-catalyzed aerobic oxidative cyclization between 2-aminobenzothiazole and ketone/chalcone for the synthesis of benzo[d]imidazo[2,1-b]thiazole is described. A variety of fused benzoimidazothiazole derivatives are obtained by this protocol.

Copper-catalyzed regioselective synthesis of furan via tandem cycloaddition of ketone with an unsaturated carboxylic acid under air.

A catalytic decarboxylative annulation has been developed for the regioselective synthesis of trisubstituted furans by the cycloaddition of ketones with α,β-unsaturated carboxylic acids under ambient air. A library of furan derivatives were obtained in good yields from the readily available substrates in the combination of a catalytic amount of Cu-salt and a stoichiometric amount of water. Water plays a crucial role in this catalytic transformation.

Copper(I)-catalyzed oxidative coupling between 2-aminobenzothiazole and terminal alkyne: formation of benzothiazine.

An unprecedented formation of benzothiazine during copper(I)-catalyzed oxidative coupling of 2-aminobenzothiazole and terminal alkyne in air has been observed. This unique transformation possibly occurs through the ring opening of 2-aminobenzothiazole and subsequent oxidative coupling with alkyne followed by intramolecular cyclization. A variety of substituted benzo[b][1,4]thiazine-4-carbonitriles are obtained by this protocol.

Functionalization of an sp(3) C-H bond via a redox-neutral domino reaction: diastereoselective synthesis of hexahydropyrrolo[2,1-b]oxazoles.

A diastereoselective synthesis of pyrrolidinooxazolidines was achieved by a metal-free, base-promoted reaction of pyrrolidine and aromatic aldehydes under microwave irradiation. The rare functionalization of an sp(3) C-H bond probably results from an in situ generated azomethine ylide that undergoes cycloaddition with aldehydes.