Studies On Transition Metal-Catalyzed Trifluoromethylation And Carbon-Nitrogen Bond Formation Reactions

This thesis mainly aims at the studies on the copper catalyzed trifluoromethylation of unsaturated carbon-carbon bonds and transition metal catalyzed carbon-nitrogen bond formation reactions, which chiefly involve the following seven chapters.Chapter I:In chapter I, the very recent progress in transition-metal catalyzed incorporation of CF3 groups across unsaturated carbon-carbon bonds is summarized in detail. According to different reaction types, we facilitated a detailed description of two different reactions. (1) transition-metal-catalyzed difunctionalization-type trifluoromethylation reaction to realize hydrotrifluoromethylation of unactivated alkenes, allyl trifluoromethylation of unactivated alkenes, simultaneous formation of C-CF3 and C-C or C-heterom bonds by formal addition reactions to alkenes. (2) transition-metal-catalyzed difunctionalization-type trifluoromethylation reaction to realize hydrotrifluoromethylation of unactivated alkynes, construction of trifluoromethylated allenes, simultaneous formation of C-CF3 and C-C or C-heterom bonds by formal addition reactions to alkynes.Chapter Ⅱ:In chapter Ⅱ, the classic transition metal-catalyzed cyclization of enynes is discussed briefly. And then, a novel copper-catalyzed trifluoromethylation-cyclization of simple 1,6-enynes using the C-C triple bonds as nucleophiles is described in detail. The reaction proceeds efficiently in a highly regioselective manner to give various trifluoromethylated carbocycles and heterocycles under mild conditions. Preliminary mechanistic studies revealed that the [CF3+] and [CF3] species are likely both generated at first step.Chapter Ⅲ:In chapter III, the recent development of transition metal-catalyzed trifluromethylation of alkynes is summarized briefly. And then, a novel copper-catalyzed one-pot trifluoromethylation/ aryl migration/carbonyl formation of homopropargylic alcohols is described in detail. A series of 3-butenal and 3-buten-l-one derivatives containing a C=C-CF3 subunit have been obtained in moderate to good yields under mild conditions. The control experiments and density functional theory (DFT) studies indicate that the reaction is initiated by the addition of the CF3 radical to the alkynes.1,4-Aryl migration can be realized through the 5-ipso cyclization.Chapter IV:In chapter IV, the developments of transition metal catalyzed caTbon-nitrogen bond formation via carbon-hydrogen bond activation and cross-coupling reaction were summarized in detail. We facilitated a detailed description from two aspects: (1) Formation of the carbon-nitrogen bond with pre-activated animating reagent; (2) Formation of the carbon-nitrogen bond via cross-dehydrogenative couplings reaction.Chapter V:In chapter V, we have developed a palladium/copper-catalyzed intermolecular direct C-H amination and chloroamination of indoles using chlorosulfonamides as the nitrogen source. This methodology allows the synthesis of a variety of 2-amino-substituted indoles, which exhibits excellent regio-selectivity and high functional group tolerance at room temperature.Chapter VI:In chapter VI, an efficient copper catalysis system for the chloroamination of alkynes with chlorosulfonamide at room temperature is described in detail, providing an efficient route to widely used (E)-β-chloro-ensulfonamides in a highly regio-and stereoselective fashion.Chapter VII:In chapter VII, the traditional methods for the synthesis of isoxazoles were briefly described. Next, we described a novel ferric-catalyzed aerobic oxidative reaction to synthesize disubstituted isoxazoles from homopropargylic alcohol, tBuONO and H2O under mild conditions in detail. Preliminary mechanistic studies revealed that H2O was essential for this transformation.