Ethylene Oxide Molecules Catalyzed Olefin Theoretical Study Of The Reaction

Chiral epoxides are highly useful intermediates and building blocks which can synthesize various biologically active compounds,they are also one type of materials with corrosion resistant and cohesiveencess which are widely usued in markets of industry. It is important to synthesize various biologically active compounds. Recently asymmetric epoxidation of olefins has attracted considerable attention and remarkable progresses have been made. Studying the mechanism can explain the result of the experiment and provide theoretical guide for the development of new high-efficiency catalysts. In this paper, we studied two kinds of chiral ketones to investigate a detailed mechanistic about the asymmetric epoxidation of different olefins using density functional method.We studied the detailed mechanism and enantioselectivity of asymmetric epoxidation of methyl cinnamate and phenyloxiranemethanol catalyzed by diacetate chiral ketone first using density functional theory (DFT) at B3LYP/6-31+G* levels of theory. The structures of each stationary point and the transition states were located. The results indicate that the reactions proceed by two steps: the detailed catalytic cycle for the oxidization of diacetate chiral ketone by H2O2 and asymmetric epoxidation of olefins. The calculations reveal a favorable free energy pathway for the oxidization of diacetate chiral ketone by H2O2. As the combination of CH3CN-H2O2 approaches the catalyst, a prereactive compound Int0 forms. The transition vector corresponds to the simultaneous transfer of the OH the O atoms of Int0 to the C and the O atoms of catalyst respectively. Dioxirane is formed via TS2 from the intermediate Int1, it is concerted reaction. The favoreable channels of asymmetric epoxidation of methyl cinnamate and phenyloxiranemethanol are investigated in detail for comparison. It has proved that the diacetate chiral ketone is more effectic to ester than to alcohol.In the fourth paper we studied the detailed mechanism and enantioselectivity of asymmetric epoxidation of 1-phenylpropene and 1-Phenyl-1-fluoropropene using density functional theory (DFT) at B3LYP/6-31+G* levels of theory. Fluorine has unique steric and electronic properties and is widely used to alter the properties of organic molecules. It is foreseeable that fluorinated olefins may display different steric and electronic properties for the epoxidation with chiral ketones as compared to their nonfluorinated counterparts. We decided to investigate the asymmetric epoxidation of monofluorinated olefins using chiral dioxiane 2a'and 2b'to epolore the effect of fluorine on reactivity and enantioselectivity. We studied the detailed mechanism and enantioselectivity of asymmetric epoxidation of 1-phenylpropene and 1-Phenyl-1-fluoropropene by chiral dioxirane 2a'and 1-Phenyl-1-fluoropropene by chiral dioxirane 2b'. The O transfers from chiral dioxirane to the olefin and form epoxide. It has two channels S and R. The favoreable channels of asymmetric epoxidation of 1-phenylpropene and 1-Phenyl-1-fluoropropene are found in detail for comparison.