BITHIENOLs: Promising<i>C</i><sub>2</sub>-Symmetric Biheteroaromatic Diols for Organic Transformation
作者:Sara Gabrieli、Roberto Cirilli、Tiziana Benincori、Marco Pierini、Simona Rizzo、Sergio Rossi
DOI:10.1002/ejoc.201601353
日期:2017.1.26
2,2',5,5'-Tetraphenyl-3,3'-bithiophene-4,4'-diol, the first member of a new class of chiral C2-symmetric atropoisomeric diols based on a biheteroaromatic scaffold, was synthesized. Dynamic enantioselective HPLC experiments provided a racemization barrier of 22.9 kcal/mol at 25 °C which was high enough to permit the chromatographic collection of both the enantiomers at semipreparative scale, but at
合成了 2,2',5,5'-Tetraphenyl-3,3'-bithiophene-4,4'-diol,这是基于双杂芳族支架的新型手性 C2 对称阻转异构二醇的第一个成员。动态对映选择性 HPLC 实验在 25 °C 下提供了 22.9 kcal/mol 的外消旋屏障,这足以允许以半制备规模对两种对映异构体进行色谱收集,但在不对称催化中作为促进剂应用的边界。通过 DFT 计算确定了对映异构化过程中涉及的基态和过渡态,这表明存在互变异构体的中间体,其中存在 thiophene-3-ol 单元和 2,3-dihydro-thiophene-3-one 环. 外消旋机制得到动态 HPLC 实验的支持。