Transition Metal-catalyzed Organic Reactions

Transition metal-catalyzed coupling reactions represent an extremely versatile tool in organic synthesis. Due to their low price and toxicity, Cu salts have recently emerged as novel catalysts in coupling reactions of unsaturated carbons, whose replacement of toxic and expensive Pd and Ni catalysts will greatly improve the chemical industry in both the economic and environmental aspects. To date now, the development of the Cu catalysts in coupling reactions was summarized C–C, C–N, C–O, C–S, C–Se, C–P, as well as C–X coupling reactions. Indium tirhalide is a mild green catalyst for organic synthesis in a highly chemo-, region-, and stero-selectively fashion in green solvent such as aqueous and alcoholic media. In this paper, some applications of indium tirhalide in organic synthesis are rexiewed including aldol reaction, Friedel-Crafts reaction, the rearrangement of epoxides, the synthesis ofα-aminophosphonates, the synthesis of quinolines, the transesterification, the hetero Diels-Alder reaction, the synthesis of chiral furan diols, the azidolysis in aqueous media and the dithioacetalization. At the same time, our works on the application of indium trihalide in Biginelli reaction and reductive deoxygenation reaction area are also dicussed. The potential superiority of indium trihalide in organic synthesis will promote the development of"Green Chemistry".In this thesis, The main works were summarized as follows:1. We have developed a new novel, practical and environmentally friendly method for the synthesis of N-arylazoles through a C-N coupling of azoles and arylboronic acids by using Silica–NHC–Cu(Ⅰ) as catalyst under air reaction conditions. The reactions generated the corresponding N-arylazoles in high yields and were applicable to Arylboronic acids. In addition, this methodology offers the competitiveness of recyclability of the catalyst without significant loss of catalytic activity, and the catalyst could be readily recovered and reused for six cycles, thus making this procedure environmentally more acceptable, whilst no catalyst leaching was observed.2. We have developed a new novel, practical and environmentally friendly method for the synthesis of alkynylphosphonates through a C-P coupling of terminal alkynes and H-phosphonates by using Silica–NHC–Cu(Ⅱ) as catalyst at room temperature under air reaction conditions. The reactions generated the corresponding alkynylphosphonates in high yields and were applicable to aromatic and aliphatic alkynes. In addition, this methodology offers the competitiveness of recyclability of the catalyst without significant loss of catalytic activity, and the catalyst could be readily recovered and reused for six cycles, thus making this procedure environmentally more acceptable, whilst no catalyst leaching was observed.3. A highly efficient synthetic strategy toward Michael addition of indoles toα,β-unsaturated esters has been developed using Lewis acid InBr3 as catalyst. The reactions generated 3-substituted indoles in high yields with excellent regio-selectivity in the presence of catalytic amount of InBr3 under mild reaction conditions. The method is simple, efficient and practical.