The Study Of Synthesis And Ring Expansion Of Three-membered Cyclic Compounds

The cyclopropane is not only the basic structure of the natural products, but also an important class of organic synthetic intermediates. It is widely presented in many microorganisms and non-natural molecules having biological activity. Due to the special geometry of the cyclopropane, it has strong ring strain and relatively unstable property, therefore, it is easy to undergo ring-opening reactions to generate stable open-chain compounds or ring expansion reactions to transform to other types cyclic systems with four to six membered atoms. As a versatile three-carbon building block, cyclopropane derivatives are widely used in modern organic chemistry and the ring expansion reaction has been practically concerned. In this thesis we investigated the ring expansion reaction of cyclopropane and the formation of a series of substituted pyrrole derivatives, which provided an effective synthetic method for the aminoyrrole derivatives. We also used isatin as the starting material, which is simple and easy to get, to develop some new reactions and synthesized of spirocyclopropyl compounds.1. Under the catalysis of Lewis acid Co(ClO4)2, the reaction of the sterically hindered1,1,2,3-tetrasubstituted cyclopropanes with aromatic imines or arylamines in refluxing THF generated a series of novel fully substituted pyrrole derivatives with sequential ring-opening of cyclopropane. All products were characterized by IR,1H NMR,13C NMR, LC-MS spectroscopy. The single crystal structures of five products were determined with X-ray diffraction method.2. The cycloaddition reactions of a series of functionalized pyridinium salts, which were generated from reaction of pyridine with active alkyl halides such as p-nitrobenzyl bromide, phenacyl bromides and bromoacetates, with3-phenacylideneoxindoles in the presence of triethylamine showed very interesting molecular diversities. A series of the functionalized spiro [cyclopropane-1,3’-indolines],3-furan-3(2H)-ylidene)indolin-2-ones and3-(2-oxoindolin-3-ylidene)butanoates were successfully prepared depending upon the structures of the pyridinium salts and reaction conditions. The regioselectivity and stereoselectivity of the reactions as well as reaction mechanisms were briefly discussed. All the products were characterized by IR,1H NMR,13C NMR, LC-MS spectroscopy. The single crystal structures of two products were determined by X-ray diffraction method.3. A series of the functionalized spiro[indoline-3,2’-oxiran]-2-ones were efficiently synthesized by Darzens reaction of phenacyl bromides with isatins both with N-alkyl groups and without N-substituent in the presence of potassium carbonate as base catalyst. When two molar phenacyl bromides were used in the reaction, the N-substitution reaction of isatin was also finished with the formation of spiro-oxirane-oxindoles. All the products were characterized by IR,1H NMR,13C NMR, LC-MS spectroscopy. The single crystal structures of three products were determined by X-ray diffraction method.