Iron(III)-Catalyzed Regioselective Synthesis of Electron-Rich Benzothiazoles from Aryl Isothiocyanates via C-H Functionalization.

We report herein a direct synthetic route for the preparation of 2-arylbenzothiazoles using aryl isothiocyanates and electron-rich arenes. The synthetic route involves triflic acid promoted addition of the arenes to aryl isothiocyanates followed by FeCl3-catalyzed C-S bond formation via C-H functionalization. The approach provides the advantage of synthesis of benzothiazoles without the conventional use of aryl aldehyde/carboxylic acid precursors employing the less expensive iron(III) catalyst.

Room-Temperature Cu(II)-Catalyzed Chemo- and Regioselective Ortho-Nitration of Arenes via C-H Functionalization.

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.

Room-temperature Cu(II)-catalyzed chemo- and regioselective ortho-nitration of arenes via C-H functionalization.

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 has been described with good functional group compatibility. The procedure features the use of an 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.

Organocatalytic syntheses of benzoxazoles and benzothiazoles using aryl iodide and oxone via C-H functionalization and C-O/S bond formation.

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.

Pd(II)-catalyzed aminotetrazole-directed ortho-selective halogenation of arenes.

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.

Iodobenzene catalyzed C-H amination of N-substituted amidines using m-chloroperbenzoic acid.

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.