Dehydrative Re<sub>2</sub>O<sub>7</sub>-Catalyzed Approach to Dihydropyran Synthesis
作者:Jean-Marc I. A. Lawrence、Paul E. Floreancig
DOI:10.1021/acs.orglett.0c03526
日期:2020.12.18
Monoallylic 1,3- and 1,5-diols undergo Re2O7-mediated ionization to form allylic cations that engage in cyclization reactions to form dihydropyran products. The reactions give the 2,6-trans-stereoisomer as the major products as a result of minimizing steric interactions in a boat-like transition state. The results of these studies are consistent with cationic intermediates, with an intriguing observation
单烯丙基 1,3- 和 1,5- 二醇经历 Re 2 O 7介导的电离以形成烯丙基阳离子,这些阳离子参与环化反应以形成二氢吡喃产物。由于使船状过渡态中的空间相互作用最小化,给出反应的主要产物为2,6-反式立体异构体。这些研究的结果与阳离子中间体一致,在一个例子中对立体化学保留进行了有趣的观察。