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A concise synthesis of pyrazolo[1,5-a]indole derivatives by copper-catalyzed aerobic oxygenation and cyclization of indoles with oxime acetates is described. This protocol represents an elegant example of N-1, C-2, and C-3 tri-functionalization of indoles in one-pot. Mechanistic studies indicate the reaction proceeds through a radical procedure. Oximes as an internal oxidant have been demonstrated to be a driver to initiate aerobic oxidation, which provides a new oxidative pattern for C-H functionalization even with high atom- and step-economy. [ABSTRACT FROM AUTHOR]

Palladium-catalyzed ortho-acylation of arenes with aldehydes in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant under aqueous conditions has been demonstrated. The acylation reaction exhibits excellent regioselectivity and wide functional group tolerance. [ABSTRACT FROM AUTHOR]

An iodine-catalyzed sulfenylation of free indoles with sodium sulfinates is described. The reaction selectively afforded 3-arylthioindoles in good to high yields in anisole under metal-free conditions. Functional groups such as halogens were well tolerated under the optimized reaction conditions. [ABSTRACT FROM AUTHOR]

Iodine-catalyzedselective 2-arylsulfonyl indole formation fromindoles and sodium sulfinates is disclosed. Various substituted 2-arylsulfonylindoles were obtained in one pot in the absence of metal catalystat room temperature under air. [ABSTRACT FROM AUTHOR]

A three-component strategy was developed for 3-phenyl-9 H -imidazo[1,5- a ]indol-9-one preparation from indole-2-carboxaldehydes, aromatic aldehydes, and ammonium acetate under copper catalysis conditions. In this process, a new five-membered ring was formed and the C3 position in the indole substrate was selectively oxidized into a ketone skeleton using oxygen as the sole oxidant and ammonium acetate as the nitrogen source. Furthermore, same products also could be achieved from indole-2-carboxaldehydes and benzyl amines under similar reaction conditions.

A metal-free method for the construction of 2-substituted quinolines and benzo[ f ]quinolines from aromatic amines, aldehydes, and tertiary amines has been demonstrated. Cheap and readily available tertiary amines acted as the vinyl source. A new pyridine ring was selectively formed via [4 + 2] condensation that was promoted by ammonium salt under neutral conditions and an oxygen atmosphere. This strategy provided a new route for the preparation of various quinoline derivatives with different substituents at the pyridine ring, which provides the possibility of further modification.

A CuBr 2 -catalyzed annulation of 2-bromo- N -arylbenzimidamide with selenium/sulfur powder for the synthesis of benzo[ d ]isoselenazole and benzo[ d ]isothiazole in generally good yields was investigated. This synthetic strategy features good substrate scope and functional group tolerance. Furthermore, the corresponding products could be converted into N -aryl indoles via rhodium III -catalyzed ortho C-H activation of the N -phenyl ring, providing an efficient approach for axial aromatic molecules.

A Pd-catalyzed C-O cross-coupling of O -acyl hydroxylamines and tertiary or secondary alkyl electrophiles was reported without the cleavage of the rather fragile N-O bond. The described strategy provides direct access to congested N , N , O -trisubstituted hydroxylamines bearing an α-quaternary carbon center under mild conditions in high yields and features exclusively chemoselective C-O bond formation, a broad substrate scope, and excellent functional group tolerance. The synthetic potential of the cross-coupling was established via pharmaceuticals derivatizations and a series of postcatalytic modifications.

We have introduced a metal-free facile access for the thiolation/aromatization of cyclohexanones with thiophenols to the corresponding aryl sulfides. The dehydroaromatic reaction of non-aromatic cyclohexanones proceeded smoothly using oxygen as a green oxidant.

A metal-free strategy for the synthesis of benzocarbazoles from 2-arylindoles and aryl ketones is developed. Various 2-aryl-3-vinyl-indoles were generated in situ through dehydrative condensation of aryl ketones and indoles. These key intermediates could be selectively converted into the corresponding benzo[ a]carbazoles via a direct cyclization process between two Csp 2 -H bonds. Furthermore, terminal alkynes also could be used as the versatile C2 source to afford the corresponding products in good yields.

A silver-mediated oxidative vinylic C-H bond sulfenylation of enamides was developed. This method is compatible with diaryl and dialkyl disulfides to deliver biologically precious chalcogenated olefins efficiently. A plausible non-chain radical mechanism was proposed for understanding this novel sulfenylation based on the mechanistic studies.

An efficient method was developed for the direct acylation of arene sp(2) C-H bonds with alcohols using palladium chloride as a catalyst and peroxide as the oxidant. The alcohols were oxidized to their corresponding aldehydes in situ and efficiently coupled with 2-arylpyridines to give aryl ketones in chlorobenzene.