Fundamental Research of Reactivity and Usage of Reagents Fluorine

近年来，含氟化合物已成为有机合成的重要中间体。然而，在理论方法中处理F原子的许多困难阻碍了该方法在研究F原子与原子的反应机理方面的广泛应用。在本研究中，我们使用从头算分子轨道计算和密度泛函理论，计算了独特的含氟化合物的物理化学性质和反应机理，并证明了其对含氟化合物的有效性。我们开展了以下工作：(1)DAST用于2-羟基嘧啶与三甲基硅基重氮甲烷选择性甲基化反应的新用途，(2)DAST对2-羟基-3-苯基甲酸乙酯的氟化反应机理的理论研究，(3)对F_2C=C(Oms)BME_3^-中乙烯基碳取代的三种可能机理的从头算分子轨道研究，(4)类S_N1机理下F_2C=C(Oms)BME_3^-中乙烯基碳取代的从头算分子轨道研究。前两项研究旨在证明著名的氟化试剂DAST(二乙氨基硫代硫化物)的独特性质。密度泛函计算表明，DAST与H2O反应生成的强酸是2-羟基嘧啶选择性甲基化的关键。后两者致力于阐明氟化合物F_2C=C(OMS)BME_3^-中sp^2碳的取代反应机理。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.