Novel Conversions of Furandiols and Spiroacetal Enol Ethers into Cyclopentenones: Implications of the Isomerization Mechanism of 2-Furylcarbinols into Cyclopentenones
作者:Biao-Lin Yin、Yu-Lin Wu、Jin-Qiang Lai
DOI:10.1002/ejoc.200900129
日期:2009.6
acid-catalyzed conversions of furandiols 8 and its dehydration spiroacetalized products 9 into oxabicyclic cyclopentenones 10 in good to excellent yields are reported. To disclose the mechanism of these conversions, the fact that H2O catalyzes the conversion of 9 into 10 is presented and intermediates 9k and 20i have been structurally verified. In addition, two other related conversions of spiroacetal enol ethers
据报道,呋喃二醇 8 及其脱水螺旋缩醛产物 9 在酸催化下转化为氧杂双环环戊烯酮 10 的产率很高。为了揭示这些转化的机理,提出了 H2O 催化 9 转化为 10 的事实,并且中间体 9k 和 20i 已在结构上得到验证。此外,还提出了另外两个相关的由 8 衍生的螺缩醛烯醇醚 11 和 14 向环戊烯酮的转化,其中分子内醛醇反应是关键步骤。基于这些结果,我们提出这些转化是通过羟醛缩合步骤而不是之前报道的 4 π 电子系统的电环化发生的。((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)