Stereoselective Sequential [4+2]/[2+2] Cycloadditions Involving 2‑Alkenylindolenines: An Approach to Densely Functionalized Benzo[b]indolizidines

A stereoselective sequential [4+2]/[2+2]
cycloaddition process
involving 2-alkenylindolenines has been developed. This unprecedented
protocol allows a rapid access to densely functionalized benzo­[b]­indolizidines containing a fully substituted piperidine
ring with five contiguous stereogenic centers in good yields with
excellent diastereoselectivities. This finding demonstrated the unique
synthetic utility of the 2-alkenylindolenine species in the construction
of complex polycyclic N-heterocycles.

一种涉及2-烯丙基茚满的[4+2]/[2+2]立体选择性串联环加成过程已被开发。该前所未有的协议可快速合成含有全取代哌啶环、五个连续立体中心的稠密官能团化的苯并[b]吲哚并啶，以良好的产率和优异的构型选择性实现。此发现展示了2-烯丙基茚满物种在构建复杂多环N杂环结构中的独特合成效用。（[4+2]/[2+2]立体选择性串联环加成过程，involving 2-alkenylindolenines）