The Study Of Multicomponent Reactions Of Electron-deficient Alkynes

In recent years, multicomponent reaction known as a green chemical synthetic method has been received wide concern. The Huisgen’s1,4-dipoles, which are easily generated from the addition of nitrogen heterocycles or amines to electron-deficient alkynes, showed diverse reactivity and have taken part in versatile reactions including nucleophilic addition,1,4-dipolar addition and so on. Recently Huisgen’s1,4-dipoles have been widely used in multicomponent reactions for developing a number of carbon-carbon bond formation reactions and heterocyclic constructions, and showed much potential applications in pharmaceutical chemistry and synthetic organic chemistry.In this thesis we have studied several new multicomponent reactions of Huisgen’1,4-dipoles via the addition of nitrogen heterocycles or amines to electron-deficient alkynes, and successfully synthesized a series of1,4-dihydropyridine,1,2-dihydropyridine derivatives and dispirooxindole-fused heterocycles. Thus several new effective synthetic methods for the design and synthesis of nitrogen-containing compounds and spiro compounds are successfully developed.1. In the presence of triethylamine as base catalyst, the domino reactions of arylamines, methyl propiolate, aromatic aldehydes and the substituted acetonitriles catalyst resulted in the functionalized2-aminodihydropyridines and2-pyridinones depending on the structures of the substrtates. Reactions involving malononitrile and cyanoacetamide gave exclusively2-aminodihydropyridines. On the other hand, ethyl cyanoacetate afforded the3-cyano-2-pyridinones as main products. All products were characterized by IR,1H NMR,13CNMR, LC-MS spectroscopy. The single crystal structures of seven prepared compounds were determined by X-ray diffraction method.2. A practical procedure for the preparation of fused1,4-dihydropyridines was developed through the domino four-component reactions of arylamines, acetylenedicarboxylate, aromatic-aldehydes, and cyclic1,3-diketones in acetic acid. The unusual fused1,2-dihydropyridines can also be efficiently prepared by controlling the reaction conditions. All products were characterized by IR,1H NMR,13C NMR, LC-MS spectroscopy. The single crystal structures of seven products were determined by X-ray diffraction method.3. A facile synthetic protocol was developed for the efficient synthesis of complex dispirooxindole-fused heterocycles via a three-component reaction. The key strategies involve a domino1,4-dipolar addition and Diels-Alder reaction of the in situ generated Huisgen’s1,4-dipoles from the addition reaction of4-dimethylaminopyridine with acetylenedicarboxylate to3-phenacylideneoxindole. All products were characterized by IR,1H NMR,13CNMR, LC-MS spectroscopy. The single crystal structures of five spiro compounds were determined by X-ray diffraction method.