Our recent progress in transition metal-catalyzed C-H oxidation reactions is summarized. The effect of catalysts, oxidants and solvents on the C-H bond oxidative cleavage reactions is described, and the mechanisms of these C-H oxidation reactions are also discussed.

Benzopyran derivatives R 0350 Cy2NH·HX-Promoted Cyclizations of o-(Alk-1-ynyl)benzoates and (Z)-Alk--2-en-4-ynoate with Copper Halides to SynthesizeIsocoumarins and α-Pyrone. -A simple protocol for the cyclization of substrates (I) and (V) is elaborated. The reaction gives halogenated pyrone derivatives in good yields. -(LIANG, Y.; XIE, Y.-X.; LI*, J.-H.; Synthesis 2007, 3, 400-406; Coll. Chem. Chem. Eng., Hunan Norm. Univ., Changsha, Hunan 410081, Peop. Rep. China; Eng.) -Mais 22-121

A simple and selective protocol for the halogenation of indoles with copper(II) bromide or chloride to synthesize 2-halo-, 3-halo-, and 2,3-dibromoindoles was developed. It was found that both base and water could be used as switches for the selectivity of the halogenation reactions. In the presence of copper(II) halide and sodium hydroxide, 3-haloindoles were obtained as the major products, whereas the selectivity was shifted toward 2,3-dihaloindoles when water was added instead of sodium hydroxide. Moreover, 2-halogenations of 3-substituted indoles were also performed successfully in moderate to good yields under the standard conditions.

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