Heteropolyacid catalyzed <i>O</i>-alkylation of oximes with alcohols <i>via</i> a carbocation in dimethyl carbonate and mechanism insight
作者:Hongfeng Zhuang、Qin Hou、Feng Han、Haotian Lv、Chengxia Miao
DOI:10.1039/d2gc03214g
日期:——
high bioactivities in organic chemistry. There are few reports about the direct construction of C–O bonds by O-alkylation of oximes with alcohols, particularly the development of catalytic systems. Herein, a simple catalytic system only including H3PW12O40·xH2O was established for the O-alkylation of oximes with alcohols in dimethyl carbonate as the green solvent, which simplified the reaction systems
C-O键作为重要的结构骨架,在有机化学中表现出很高的生物活性。关于通过肟与醇的O-烷基化直接构建 C-O 键的报道很少,特别是催化体系的开发。本文以碳酸二甲酯为绿色溶剂,建立了仅含H 3 PW 12 O 40 · x H 2 O的简单催化体系,用于肟与醇的O-烷基化反应,简化了反应体系,实现了催化转化,提高了催化效率。产率和选择性。所开发的体系具有广泛的底物适用范围和良好的官能团耐受性。它适用于O-芳香族或脂肪族酮肟和醛肟,以及带有杂原子的肟与苯甲醇、脂肪醇、烯丙醇等的烷基化,产率高达98%。而肟醚的克级反应和进一步转化也取得了较好的进展。三苯甲基四氟硼酸酯代替三苯甲醇仍然生成所需的产物,这表明 Ph 3 C +会被肟捕获,反应经历碳阳离子过程。紫外-可见光谱中 404 和 433 nm 处新波段的出现和减弱进一步证明了反应过程中碳正离子的形成。FT-IR光谱中吸收峰的变化和不同酸的对照实