A Divergent and Selective Synthesis of Isomeric Benzoxazoles from a Single N–Cl Imine
作者:Cheng-yi Chen、Teresa Andreani、Hongmei Li
DOI:10.1021/ol202844c
日期:2011.12.2
divergent and regioselective synthesis of either 3-substituted benzisoxazoles or 2-substituted benzoxazoles from readily accessible ortho-hydroxyaryl N–H ketimines is described. The reaction proceeds in two distinct pathways through a common N–Cl imine intermediate: (a) N–O bond formation to form benzisoxazole under anhydrous conditions and (b) NaOCl mediated Beckmann-type rearrangement to form benzoxazole
描述了从容易获得的邻羟基芳基NH酮亚胺中发散和区域选择性合成3-取代的苯并异恶唑或2-取代的苯并恶唑的方法。反应通过共同的N–Cl亚胺中间体以两种不同的途径进行:(a)在无水条件下形成N–O键形成苯并异恶唑;(b)分别由NaOCl介导的贝克曼型重排形成苯并恶唑。反应路径还取决于芳环的电子性质,富电子的芳环有利于重排,缺电子的环有利于N–O键的形成。提出了通过[1,2]-芳基净迁移的贝克曼型重排机制,用于形成2-取代的苯并恶唑。