The Study Of Multicomponent Tandem Reactions Containing With Electron-deficient Alkynes

Multicomponent reactions’s (MCRs) have attracted a lot of attention in recent years due to convergence, productivity, facile execution and generation of highly diverse and complex products from easily available starting materials in a single operation. Huisgen1,4-dipoles, which are easily formed from the adding of nucleophiles such as nitrogen heterocycles, amines, isocyanides, carbene or organophosphorus compounds to electron-deficient alkynes show diverse reactivity and have token part in versatile reaction including condensation,1,4-dipolar addition and arrangement reactions. Recently Huisgen1,4-dipoles has been widely used in multicomponent reactions to develop a number of carbon-carbon bond formation reaction and heterocyclic constructions. In this thesis we wish to report our study on the multicomponent reactions with electron-deficient alkynes and the efficient synthesais of zwitterionic salts, polysubstituted dihydropyridines and polysubstituted dihydropyrans.1. A practical synthetic procedure for the preparation of the charge-separated pyridinium-Meldrum acid zwitterionic salts was developed through a one-pot three component reaction of pyridine, acetylenedicarboxylate and1,3-diketones. Totally twenty-three new compounds were prepared and characterized by NMR, IR, LC-MS spectroscopy and single crystal structure of five new heterocyclic compounds were confirmed by X-ray diffraction.2. A practical and efficient procedure for the preparation of the polysubstituted dihydropyridines was developed through the four-component reaction of aromatic aldehydes, malononitrile, arylamines, and acetylenedicarboxylate with triethylamine as base catalyst. Malononitrile can be replaced by ethyl cyanoacetate, cyanoacetamide and pivaloylacetonitrile. This four-component reaction is atom efficient, high-yielding and applicable to a wide variety of four reaction components. Fifty-nine new compounds were fully characterized by spectroscopic methods and confirmed by single-crystal X-ray diffraction of eight compounds.3. An unprecedented protocol has been developed for the efficient synthesis of structurally diverse3,4-dihydropyridin-2(1H)-ones and3,4-dihydro-2H-pyrans via readily accessible four-component reactions of arylamines, acetylenedicarboxylate, aromatic aldehydes and cyclic1,3-diketones. On the other hand the four-component reactions containing ethyl acetoactate yield polysubstituted dihydropyridines as main products. Totally thirty-nine new heterocyclic compounds were prepared and characterized by NMR, IR, LC-MS spectroscopy and single crystal structures of five compounds were confirmed by X-ray diffraction.