The anomeric effect of the carhoethoxy group in oxygen and sulphur containing heterocycles
作者:C. Tschierske、H. Köhler、H. Zaschke、E. Kleinpeter
DOI:10.1016/s0040-4020(01)89165-1
日期:——
The anomeric effect of the carboethoxy substituents and the ring oxygen in 1,3-dioxane- and 1,3-oxathiane-2-carboxylates has been estimated in low polar solvents by including empirical correlation factor α to be 4 kJ/mol. The conformational energies of the 2-carboethoxy substituent fit well the parabolic Zefirov dependence on the solvent dielectric constant in the 1,3-dioxane2-carboxylates. Deviations
在低极性溶剂中,通过将经验相关因子α包括为4 kJ / mol,可以估算出1,3-二恶烷和1,3-氧杂蒽-2-羧酸酯中的碳乙氧基取代基和环氧的异头作用。2-羧乙氧基取代基的构象能很好地拟合了抛物线型Zefirov对1,3-二恶烷2-羧酸酯中溶剂介电常数的依赖性。在1,3-氧杂蒽-2-羧酸酯的情况下与之的偏离表明所涉及的第二构象平衡是COOR取代基围绕到环外键的旋转。优选的旋转异构体已经被分配并在特殊π的角度讨论CO / 3D (S)轨道相互作用。