Computer-Aided Reaction Design. Development of a New Facile Procedure to Synthesize 2-Mercapto-3-alkoxycarboxylate on the Basis of ab Initio Molecular Orbital Calculations
作者:Shohei Fukuda、Yuji Akiyoshi、Kenzi Hori
DOI:10.1021/jo990055n
日期:1999.6.1
beta-unsaturated carboxylate ester as a main product. The difference of carboxylate moiety in the substrate causes remarkable change in reactivity and selectivity. To clarify origin of the difference, ab initio MO calculations in the gas phase and in DMF have been carried out. The solvent effect was considered at RHF/6-31+G with the IPCM-SCRF model. It was confirmed that the substrate with an ester fragment
本文介绍了一种新的面部程序,可根据从头算算MO值,用SH(-)取代2-(甲苯磺酰氧基)链烷酸酯中的甲苯磺酰氧基,生成2-巯基链烷酸酯。底物和溶剂作用的结合可以控制2-(甲苯磺酰氧基)-3-烷氧基羧酸的反应性和反应选择性,从而以良好的收率得到2-巯基-3-烷氧基羧酸,而其乙酯得到的是α,β-不饱和羧酸酯作为主要产品。底物中羧酸根部分的差异引起反应性和选择性的显着变化。为了弄清差异的起因,已经进行了气相和DMF中的从头算MO的计算。使用IPCM-SCRF模型在RHF / 6-31 + G时考虑了溶剂作用。可以证实,具有酯片段的底物比S(N)2机制更喜欢E1cB。在具有羧酸根离子片段的S(N)2机理的过渡态中,由于COO(-)片段与SH(-)之间的静电排斥,亲核试剂SH(-)远离反应中心。这种排斥在气相中引起高活化势垒,而极性溶剂可以降低势垒高度。因此,反应条件可以控制羧酸的反应性。在对MO计算