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Self-assembled copper(II) complexes are described as effective catalysts for nitroaldol (Henry) reactions on water. The protocol involves a heterogeneous process and the catalysts can be recovered and recycled without loss of activity. Further, C2-symmetric N,N'-substituted chiral copper(II) salan complexes are found to be more effective catalysts than chiral copper(II) salen complexes for reactions in homogeneous catalysis, with high enantioselectivities. The reactions involve bifunctional catalysis, bearing the properties of a Brønsted base, as well as a Lewis acid, to effect the reaction in the absence of external additives.

An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.

Self-assembled copper(II) complexes are described as effective catalysts for nitroaldol (Henry) reactions on water. The protocol involves a heterogeneous process and the catalysts can be recovered and recycled without loss of activity. Further, C2-symmetric N,N′-substituted chiral copper(II) salan complexes are found to be more effective catalysts than chiral copper(II) salen complexes for reactions in homogeneous catalysis, with high enantioselectivities. The reactions involve bifunctional catalysis, bearing the properties of a Bronsted base, as well as a Lewis acid, to effect the reaction in the absence of external additives.

Copper(II)-catalyzed oxidative cross-coupling of anilines, primary alkyl amines, and sodium azide is described in the presence of TBHP at moderate temperature. This one-pot multicomponent protocol involves a domino C–H functionalization, transimination, ortho-selective amination, and a cyclization sequence. The broad substrate scope and functional group compatibility are the significant practical features. The protocol can be extended to the coupling of benzyl alcohols with moderate yields.

A copper(II)-mediated regioselective N-arylation of azoles has been developed using 8-aminoquinoline amide as a directing group. This reaction shows a broad substrate scope with different azoles such as pyrroles, indoles, pyrazoles and carbazole with good yields.

Copper(II)-catalyzed oxidative cross-coupling of anilines, primary alkyl amines, and sodium azide is described in the presence of TBHP at moderate temperature. This one-pot multicomponent protocol involves a domino C–H functionalization, transimination, ortho-selective amination, and a cyclization sequence. The broad substrate scope and functional group compatibility are the significant practical features. The protocol can be extended to the coupling of benzyl alcohols with moderate yields.

Copper-mediated regioselective N-arylation of pyrroles, indoles, pyrazoles and carbazole is described using 8-aminoquinoline amide as a directing group via dehydrogenative coupling. The protocol has a broad substrate scope with good yields at moderate temperature.

An efficient Cu-catalyzed chemo- and regioselective ortho-nitration of N,1-diaryl-5-aminotetrazoles and N,4-diaryl-3-amino-1,2,4-triazoles have been described with good functional group compatibility. The procedure features the use of operationally simple protocol utilizing the commercially available less toxic CuCl2·2H2O as catalyst and Fe(NO3)3·9H2O as nitration source at room temperature. Removal of the 5-aminotetrazole directing group has been demonstrated using base hydrolysis to afford substituted 2-nitroanilines.

A novel and efficient copper-catalyzed amination of N-aryl imines is described. This one-pot, multicomponent reaction, in which imine acts as a directing group by chelating to the metal center, affords a potential route for the transformation of the commercial aryl amines, aldehydes, and azides into valuable benzimidazole structural units with wide substrate scope and diversity. The synthetic and mechanistic aspects are presented.

An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C–H functionalization and C–O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.

A novel and efficient copper-catalyzed amination of N-aryl imines is described. This one-pot, multicomponent reaction, in which imine acts as a directing group by chelating to the metal center, affords a potential route for the transformation of the commercial aryl amines, aldehydes, and azides into valuable benzimidazole structural units with wide substrate scope and diversity. The synthetic and mechanistic aspects are presented.

A Pd(II)-catalyzed ortho-selective halogenation of N-aryl ring of N,1-diaryl-1H-tetrazol-5-amine has been described employing N-halosuccinimide as a halogen source via C-H bond activation. The present work features 5-aminotetrazole, as a directing group, for the chemo- and regioselective C-H halogenation of arenes. The kinetic isotope study (kH/kD = 2.9) suggests that the cleavage of the C-H bond takes place in the rate-determining step. The scope and mechanism of the protocol have been demonstrated.

The oxidative C–H amination of N″-aryl-N′-tosyl/N′-methylsulfonylamidines and N,N′-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of mCPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields.

The oxidative C–H amination of N″-aryl-N′-tosyl/N′-methylsulfonylamidines and N,N′-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of mCPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields.

An efficient Cu-catalyzed chemo- and regioselective ortho-nitration of N,1-diaryl-5-aminotetrazoles and N,4-diaryl-3-amino-1,2,4-triazoles have been described with good functional group compatibility. The procedure features the use of operationally simple protocol utilizing the commercially available less toxic CuCl2·2H2O as catalyst and Fe(NO3)3·9H2O as nitration source at room temperature. Removal of the 5-aminotetrazole directing group has been demonstrated using base hydrolysis to afford substituted 2-nitroanilines.