r2-tert-butoxy-t4,t5-dimethyl-1,3,2-λ3-dioxaphospholane | 33835-64-2

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 二氧磷杂环戊烷
• 英文名称: r2-tert-butoxy-t4,t5-dimethyl-1,3,2-λ3-dioxaphospholane
• CAS: 33835-64-2
• 化学式: C₈H₁₇O₃P
• 分子量: 192.195
• InChiKey: JUGPZJPMNZZEAV-IYOMYWLESA-N

反应信息

• 作为产物：
  描述：

  tert.-Butyl(d,l)-2,3-butandiol-phosphit 44.0 ℃ 、133.32 Pa 条件下， 生成 r2-tert-butoxy-t4,t5-dimethyl-1,3,2-λ3-dioxaphospholane
  参考文献：
  名称：

  Kinetic Studies of the Thermal cis-to-trans Isomerization of Dioxaphospholanes

  摘要：

  By following a previously reported method,(1) the synthesis of r-2-alkoxy-cis-4-cis-5-dimethyl-1,3,2-lambda(3)-dioxaphospholanes ligands (1 and 3) was carried out. The purpose of this work is the kinetic study of the inversion barrier at phosphorus for 1 and 3 and the comparison with the already informed dioxaphospholane 2. The kinetic measurements of the thermal isomerization cis-to-trans were performed by (31)P NMR spectroscopy, observing a first order kinetics for both compounds. The energy of activation (E(alpha)) for the epimerization of compounds cis-1 and cis-3 was calculated to be 16.0 +/- 0.6 and 11.8 +/- 0.8 kcal/mol, respectively. The values of the thermodynamic parameters of the transition state (Delta H(not equal),Delta S(not equal),Delta G(not equal)) suggest that the inversion at phosphorus not only depends on the spatial requirements of the alkoxy substituent but also on entropic effects. The thermodynamic parameters Delta H degrees, Delta S degrees, and Delta G degrees were also evaluated and they show that the cis isomers are preferred from enthalpic point of view, but entropic effects dominate the equilibrium trans reversible arrow cis leading to the entropically favored trans isomers. Furthermore, the results are supported by density functional theory calculations of 1-4 at the B3LYP/6-31G** level.

  DOI：

  10.1080/10426500801963822