Conformational analysis of 2-(diphenylphosphinoyl)-tetrahydrothiopyran: Lack of additivity of the S-C-P anomeric effect
作者:Mario Ordóñez、Eusebio Juaristi
DOI:10.1016/s0040-4020(97)10374-x
日期:1998.2
2-(diphenyl-phosphinoyl)thiane, ΔHo = + 1.29 ± 0.12 kcal/mol, and ΔSo = + 4.8 ± 0.7 cal/K·mol. Comparison of the enthalpic S-C-P(O) anomeric effect in the thiane and 1,3-dithiane systems, 2.68 versus 3.39 kcal/mol, respectively, leads to the conclusion that no additivity of the S-C-P(O) anomeric effect takes place.
在thiane环的α位的diphenylphosphinoyl组的构象偏好是由低温NMR估计,ΔG Ô 173K = + 0.46±0.11千卡/摩尔,和在50℃下,经由anancomeric模型的化学平衡,ΔG ö 323K= -0.26±0.10kcal / mol。这些热力学数据允许的轴向赤道构象的2-平衡(二苯基-膦酰基)的焓和熵的贡献thiane,估计ΔH Ô = + 1.29±0.12千卡/摩尔,和ΔS ö= + 4.8±0.7cal / K·mol。比较噻吩和1,3-二噻吩体系中焓焓SCP(O)的异头作用,分别为2.68和3.39 kcal / mol,得出结论:没有发生SCP(O)异头作用的可加性。