Title: Benign catalysis with zinc: atom-economical and divergent synthesis of nitrogen heterocycles by formal [3 + 2] annulation of isoxazoles with ynol ethers

Authors: Xin-Qi Zhu, Han Yuan, Qing Sun, Bo Zhou,  Xiao-Qin Han,  Zhi-Xin Zhang, Xin Lu*  and  Long-Wu Ye

Abstract:

Herein, we disclose an efficient zinc-catalyzed formal [3 + 2] annulation of isoxazoles with ynol ethers under exceptionally mild reaction conditions, leading to the atom-economical and divergent synthesis of 2-alkoxyl 1H-pyrroles and 3H-pyrroles, respectively. Importantly, this zinc-catalyzed protocol demonstrates the dramatically divergent reactivity from the relevant platinum catalysis, where the formal [4 + 2] annulation of isoxazoles with ynol ethers was involved. In addition, theoretical calculations provide further evidence for the feasibility of the proposed reaction mechanism, especially the distinct selectivity.

Full-link: http://pubs.rsc.org/en/Content/ArticleLanding/2018/GC/C8GC02051E#!divAbstract