Synthesis of Benzoxazoles via an Amine-Catalyzed [4 + 1] Annulation
摘要:
An unprecedented simple pyrrolidine catalyzed [4 + 1] annulation reaction of ynals with N-protected-2-aminophenols Is reported. The utilization of the unique property and reactivity of the C C triple bond in ynals leads to two consecutive conjugate addition reactions at the same beta-position with pyrrolidine via iminium activation. The powerful cascade process affords a new alternative approach to biologically and synthetically important benzoxazoles in high yields (83-95%).
Synthesis of Benzoxazoles via an Amine-Catalyzed [4 + 1] Annulation
作者:Aiguo Song、Xiaobei Chen、Xixi Song、Xinshuai Zhang、Shilei Zhang、Wei Wang
DOI:10.1021/ol400988e
日期:2013.5.17
An unprecedented simple pyrrolidine catalyzed [4 + 1] annulation reaction of ynals with N-protected-2-aminophenols Is reported. The utilization of the unique property and reactivity of the C C triple bond in ynals leads to two consecutive conjugate addition reactions at the same beta-position with pyrrolidine via iminium activation. The powerful cascade process affords a new alternative approach to biologically and synthetically important benzoxazoles in high yields (83-95%).