Dearomatization of electron poor six-membered N-heterocycles through [3 + 2] annulation with aminocyclopropanes
作者:Johannes Preindl、Shyamal Chakrabarty、Jérôme Waser
DOI:10.1039/c7sc03197a
日期:——
Many abundant and highly bioactive natural alkaloids contain an indolizidine skeleton. A simple, high yielding method to synthesize this scaffold from N-heterocycles was developed. A wide range of pyridines, quinolines and isoquinolines reacted with Donor-Acceptor (DA)-aminocyclopropanes via an ytterbium(III) catalyzed [3+2] annulation reaction to give tetrahydroindolizine derivatives. The products
许多丰富且具有高生物活性的天然生物碱都含有吲哚并立啶骨架。开发了一种简单,高产的方法,可从N-杂环合成该支架。各种吡啶,喹啉和异喹啉通过Don(III)催化的[3 + 2]环化反应与施主-受体(DA)-氨基环丙烷反应,得到四氢吲哚嗪衍生物。获得具有高非对映选择性(dr> 20:1)的产物作为抗异构体。另外,形成的缩醛可以通过形成亚胺,然后还原或添加亲核试剂而容易地转化为仲胺和叔胺。这种转化构成了贫电子的六元杂环通过DA环丙烷的[3 + 2]环芳烃脱芳香化作用的第一个例子。