Dynamic Kinetic Resolution of Azlactones by Bifunctional Thioureas with α‑Trifluoromethyl or Methyl Groups
作者:Marcos Hernández-Rodríguez、Eddy I. Jiménez、Margarita Cantú-Reyes、Miguel Flores-Ramos、Carlos A. Román-Chavarría、Howard Díaz-Salazar
DOI:10.1055/a-1892-9911
日期:2022.10
The asymmetric ring opening of azlactones via dynamic kinetic resolution (DKR) is investigated by contrasting thioureas incorporating 1-arylethyl substituents against their more acidic trifluoromethylated analogs. All the catalysts under study outperform Takemoto’s thiourea because of the inclusion of an additional chiral center. However, the difference in yield and selectivity between the fluorinated
通过将含有 1-芳乙基取代基的硫脲与其更具酸性的三氟甲基化类似物进行对比,研究了通过动态动力学拆分 (DKR) 的 azlactones 的不对称开环。由于包含一个额外的手性中心,所有正在研究的催化剂都优于 Takemoto 的硫脲。然而,氟化和非氟化催化剂之间的产率和选择性差异很小。我们通过分析计算的过渡态来解释这一观察结果。我们的研究结果表明,与 1-芳乙基连接的 NH 与苄氧基离子中带负电的氧之间的氢键 (HB) 在 HB 网络中最长,而铵基与同一氧原子之间的 HB 是最短。因此,