Study On The Oxidation Reaction Of Dinuclear Copper Salicylate Catalyzed By Oxygen

The selective oxidation of hydrocarbons,has attracted a graet deal of attention from organic chemists.Copper has been used widely in oxidation chemistry due to its good ability of donating and receiving electrons.In chapter 1 of the thesis,enzymes with copper as active sites for oxidation,as well as synthetic analogues of these active sites are described.Recent progress of copper catalysed oxidation of organic molecules with oxygen gas as oxidant is also presented.(1)In Chapter 2,The aerobic oxidation of N,N-dimethyl aniline compounds to the corresponding N-methyl formamide compounds catalysed by a binuclear copper-salicylate complex is disclosed.The effect of catalysts,ligands,additives and solvents were screened for the reaction.This method has broad substrate scope,and was particularly good for electron deficient substrates.The reaction takes place under mild conditions with simple operational and easy work-up procedures.(2)In Chapter 3,a mild and efficient method for the oxidation of N-aryltetrahydroisoquinolines to dihydroisoquinolones is developed,which is enabled by the relay catalysis of a binuclear Cu catalyst and a VB1 analogue with oxygen as oxidant.Mechanistic studies revealed that the copper catalyst oxidases amines to the corresponding iminium salts,which were then oxygenated to lactam products by the catalysis of the vitamin B1 analogue.The oxygenation of iminium salts to amides catalysed by NHCs appears unprecedented in the literature.Good yields and selectivities were obtained for a range of substrates.The method was successfully applied to the synthesis of the potent estrogen receptor modulators.(3)In Chapter 4,the binuclear copper-salicylate complex was found to be an active catalyst for the aerobic oxidation of N-aryltetrahydroisoquinolines to the corresponding iminium ions,which could be trapped by a wide range of nucleophiles to form coupled products.The reactions took place under 1 bar of O2 at room temperature with 1 mol%of the copper catalyst being sufficient in most cases,and are considerably accelerated by catalytic chloride anions.Mechanistic studies show that the Cu(?)dimer oxidizes the amine into the iminium and this two-electron process necessitates O2,with the resulting Cu(I)being concomitantly reoxidazed back to Cu(?).Various lines of evidence suggest that the oxidative coupling reaction is turnover-limited by the step of iminium formation,and it is this step that is promoted by the chloride anion.Being more efficient than and mechanistically distinct from the well-studied simple copper salts such as CuBr and CuCl2,the dinuclear copper catalyst provides a new tool for oxidative coupling reactions.(4)In Chapter 5,it was found the binuclear copper catalyst provides a new tool for the aerobic oxidation of alkenes to carbonyls with O2.A wide range of a-substituted styrenes were cleaved to afford benzaldehydes and aromatic ketones generally in high yields with excellent chemoselectivity and very good functional group tolerance,including those containing radical-sensitive groups.