Tharmalingam Punniyamurthy

CUO NANOPARTICLES CATALYZED C-N, C-O, AND C-S CROSS-COUPLING REACTIONS: SCOPE AND MECHANISM

CuO nanoparticles have been studied for C-N, C-O, and C-S bond formations via cross-coupling reactions of nitrogen, oxygen, and sulfur nucleophiles with aryl halides. Amides, amines, imidazoles, phenols, alcohols and thiols undergo reactions with aryl iodides in the presence of a base such as KOH, Cs(2)CO(3), and K(2)CO(3) at moderate temperature. The procedure is simple, general, ligand-free, and efficient to afford the cross-coupled products in high yield.

Ligand-Free Copper-Catalyzed Synthesis of Substituted Benzimidazoles, 2-Aminobenzimidazoles, 2-Aminobenzothiazoles, and Benzoxazoles

The synthesis of substituted benzimidazoles, 2-aminobenzimidazoles, 2-aminobenzothiazoles, and benzoxazoles is described via intramolecular cyclization of o-bromoaryl derivatives using copper(II) oxide nanoparticles in DMSO under air. The procedure is experimentally simple, general, efficient, and free from addition of external chelating ligands. It is a heterogeneous process and the copper(II) oxide nanoparticles can be recovered and recycled without loss of activity.

Copper-Mediated Synthesis of Substituted 2-Aryl-N-benzylbenzimidazoles and 2-Arylbenzoxazoles via C–H Functionalization/C–N/C–O Bond Formation

An efficient method for the transformation of N-benzyl bisarylhydrazones and bisaryloxime ethers to functionalized 2-aryl-N-benzylbenzimidazoles and 2-arylbenzoxazoles is described. The protocol involves a copper(II)-mediated cascade C-H functionalization/C-N/C-O bond formation under neutral conditions. Substrates having either electron-donating or -withdrawing substituents undergo the cyclization to afford the target heterocycles at moderate temperature.

Cobalt(II)-catalyzed oxidation of alcohols into carboxylic acids and ketones with hydrogen peroxide

The oxidation of aliphatic and aromatic alcohols into the corresponding carboxylic acid analogues and ketones has been carried out using 30% H 2 O 2 and cobalt(II) complex 1 in good to high yields. The reaction is safe, clean and functions in the absence of additives.

Copper(II)-Catalyzed Aerobic Oxidative Synthesis of Substituted 1,2,3- and 1,2,4-Triazoles from Bisarylhydrazones via C–H Functionalization/C–C/N–N/C–N Bonds Formation

An unprecedented copper(II)-catalyzed aerobic oxidative synthesis of 2,4,5-triaryl-1,2,3-triazoles and 1,3,5-triaryl-1,2,4-triazoles from bisarylhydrazones as the common starting precursor has been achieved via cascade C-H functionalization/C-C/N-N/C-N bonds formation under mild reaction conditions. One of the enthralling outcomes of this strategy is the copper(II)-catalyzed room temperature C-H functionalization/C-N bond formation in presence of air, which has been accomplished during the synthesis of substituted 1,2,4-triazoles. This new class of compounds could give prospective luminescence as an iconic component in the area of pharmaceutical and biological sciences. The intermediates for both the processes have been isolated to elucidate the mechanistic scenario.

Copper(II)-catalyzed conversion of bisaryloxime ethers to 2-arylbenzoxazoles via C-H functionalization/C-N/C-O bonds formation.

A copper(II)-catalyzed conversion of bisaryloxime ethers to 2-arylbenzoxazoles has been developed. The reaction involves a cascade C-H functionalization and C-N/C-O bond formation under oxygen atmosphere.

“On Water”: Efficient Iron‐Catalyzed Cycloaddition of Aziridines with Heterocumulenes

In suspension: the reaction of aziridines with heterocumulenes in the presence of Fe(NO(3))(3)⋅9H(2)O in aqueous suspension provides access to functionalized five-membered heterocycles in good to high yields. This protocol has a wide substrate scope, is simple, and uses a nontoxic and cheap catalyst.

Pd-catalyzed C-H activation/C-N bond formation: a new route to 1-aryl-1H-benzotriazoles.

A method for the C-H activation of aryl triazene compounds followed by intramolecular amination is described. It involves the use of a catalytic amount of Pd(OAc)(2) that efficiently effects the cyclization to provide 1-aryl-1H-benzotriazoles at moderate temperature.

Copper(II)-catalyzed direct dioxygenation of alkenes with air and N-hydroxyphthalimide: synthesis of β-keto-N-alkoxyphthalimides.

Copper(II)-catalyzed direct dioxygenation of alkenes using air and a simple N-hydroxyphthalimide leading to β-keto-N-alkoxyphthalimides has been developed. The reaction system is mild, efficient, and effective at room temperature with broad substrate scope and substantial steric hindrance. The radical-trapping and (18)O-labeling experiments have been demonstrated.

Copper-catalyzed domino intra- and intermolecular C-S cross-coupling reactions: synthesis of 2-(arylthio)arylcyanamides.

One-pot synthesis of 2-(arylthio)arylcyanamides is accomplished using cheap and air-stable CuSO(4) x 5 H(2)O as a catalyst by domino intra- and intermolecular C-S cross-coupling reactions of 2-(iodoaryl)thioureas with aryl iodides under ligand-free conditions.