Fundamental Research of Reactivity and Usage of Reagents Fluorine

含氟化合物是近年来发展起来的一类重要的有机合成中间体。然而，理论方法在处理F原子时存在许多困难，使其不能广泛应用于研究与F原子的反应机理。本研究采用从头算分子轨道计算方法和最近被证明对氟化合物有效的密度泛函理论，对独特的氟化合物的物理化学性质和反应机理进行了计算。（2）DAST对2-羟基-3-苯基炔酸酯氟化反应机理的理论研究;（3）对F_2C=C（OMs）BMe_3^-中乙烯基碳取代反应的三种可行机理的从头算分子轨道研究，（4）F_2C=C（OMs）BMe_3^-中乙烯基碳上取代的类S_N1机理的从头算分子轨道研究。前两项研究旨在证明著名的二乙氨基硫代氟化物（DAST）的独特性质。DAST与H_2O反应生成的强酸是2-羟基嘧啶选择性甲基化的关键。后两篇论文致力于阐明氟化合物F_2C=C（OMs）BMe_3^-中sp^2碳上的取代反应机理。本研究充分达到了最初的目的。

Fluorine compounds have been useful intermediates for organic synthesis in recent years. However, many difficulties in treating the F atom within theoretical method prevent the method from widely use for investigating mechanism of reactions with the atom. In the present study, we used ab intio molecular orbital calculations as well as the Density Functional theory, whose efficiency for the fluorine compounds was proved recently, were used to calculate physico-chemical property and the reaction mechanisms of unique fluorine compounds. We performed following investigations (1) A new usage of DAST for selective methylation of 2-hydroxypyrimidine using trimethyl-silyldiazomethane, (2) Theoretical Study of Fluorination mechanism of 2-hydroxy-3-phenylalkinate with DAST,(3) Ab initio Molecular orbital study on three feasible mechanisms for substitution of the vinyl carbon in F_2C=C(OMs)BMe_3^-, (4) Ab initio molecular orbital study on substitution on the vinylic carbon in F_2C=C(OMs)BMe_3^- under S_N1-like mechanism. The former two studies intended to prove unique properties of DAST(diethylaminosulfur hifluoride), a famous fluorination reagent. The Density Functional calculations showed that the reaction of DAST and H_2O produces a strong acid which is the key for selective methylation of 2-hydroxypyrimidine. The latter two were dedicated to clarify the mechanisms of substitution reactions on the sp^2 carbon in a fluorine compound, F_2C=C(OMs)BMe_3^-. The present study achieved the initial purpose sufficiently.