描述了由水杨醛和α-烯丙基化的醇产生的邻醌甲基的分子内[4 + 2]环加成反应。在催化量的苯磺酸(BSA)的存在下,反应在EtOH中顺利进行,通过三键形成工艺以中等至极好的收率和高的非对映选择性提供了呋喃[3,2- c ]苯并吡喃。该反应提供了一个简单而直接的方案,可以有效地构建呋喃[3,2- c ]苯并吡喃骨架。提出了一种可能的机制,包括半缩醛形成/杂-Diels-Alder反应,以使观察到的结果合理化。
Regioselective Synthesis of Substituted Tetrahydrofurans through Prins Cyclization
作者:Li-Ming Zhao、Fei Dou、Rui Sun、Ai-Li Zhang
DOI:10.1055/s-0033-1341273
日期:——
The synthesis of functionalizedtetrahydrofurans was accomplished through the TfOH-catalyzed Prins cyclization. The reaction proceeded regioselectively at the internal alkene carbon in the presence of catalytic amounts of TfOH to afford the five-membered ring, rather than the typical six-membered ring. Another attractive feature of this protocol is the metal catalyst-free characteristic of the cyclization