Study On The Synthesis Of Small Oganic Moleculars Catalyted By N-heterocyclic Carbene Compounds

Carbene, a most investigated reactive species in the field of organic chemistry, is a typical structural features, N-heterocyclic carbenes (NHC) are neutral and possess a bivalent carbon atom with an electron sextet. Since the first reports of stable nucleophilic carbenes—imidazol-2-ylidene by Arduengo et al. in 1991, the broad application of NHC in organic synthesis has been impressively demonstrated. Beside their role as excellent ligands in metal-based catalytic reactions, organocatalytic carbene catalysis has emerged as an exceptionally fruitful research area in synthetic organic chemistry. In this thesis, with the application of NHC catalysis, we have synthesized some useful oganic small moleculars such as benzil, pyrroles, thieno[2, 3-b]indole, spiro butyrolactone oxindole and so on. The main interesting results are as fellows:1. A simple and convenient one-pot procedure is reported for the synthesis of 1,2-diketones from corresponding benzoin-type condensation reaction of aromatic aldehydes in water with benzimidazolium salt as condensation catalyst and ferric chloride as oxidizing reagent.2. A multicomponent synthesis of highly substituted pyrroles catalyzed by thiazolium salts has been disclosed. Fistly, a series of 1, 4-dicarbonyl compounds were obtained from aldehyde and benzimidazole-chalcone with thiazolium salts as catalyst. The subsequent addition of various amines promotes a Paal?Knorr reaction, affording the desired pyrrole nucleus in an efficient one-pot process. The intermediate 1, 4-dicarbonyl compounds and highly substituted pyrroles were all characterized by NMR, IR spectra and one single crystal structure of them was determined by X-ray diffraction method.3. The substituted aniline was selected as the starting material, using Sandmeyer methodology to form isatin compounds. Then 3-arylideneindolin-2-one was obtained via Wolff-Kishner-Huang Reaction and condensation reaction. The most impotant intermediate 1, 4-dicarbonyl oxindole compounds were synthesized catalyted by thiazolium salts. At last, a series of thieno[2, 3-b]indoles were obtained promoted by the Lawson'reagent. The targent compounds were all fully characterized by NMR,IR spectra.4. We had done deep research to synthesis of spiro butyrolactone oxindole with NHC as catalyst, resulting that the corresponding product's configuration is determined by the structure of the starting substrat. We also obtained and had characterized a series of new spiro butyrolactone oxindole and had determined a product's absolute configuration by X-Ray crystal diffraction.5. We had discovered the intramolecular coupling reaction of aldehyde imines catalyzed by NHC and had got some preliminary result; We got the esterification products instead of the desired compounds of intramolecular Stetter cyclization.