Metal-Free Oxidative Annulation of Phenols and Amines: A General Synthesis of Benzoxazoles
作者:Shaofeng Wu、Furong Geng、Jianyu Dong、Long Liu、Yongbo Zhou
DOI:10.1021/acs.joc.2c00790
日期:2022.7.15
efforts toward their synthesis; however, the developed methods rely on prefunctionalized substrates and lack generality. Under metal-free conditions, a highly general synthesis of benzoxazoles direct from abundant and easily available phenols and amines is developed via a modular phenol functionalization controlled by TEMPO. In the reaction, various phenols and primary amines with a broad range of
苯并恶唑在天然产物、药物和功能材料中的普遍存在激发了许多对其合成的努力。然而,所开发的方法依赖于预功能化的底物,缺乏通用性。在无金属条件下,通过由 TEMPO 控制的模块化苯酚官能化,直接从丰富且容易获得的苯酚和胺中合成苯并恶唑。在该反应中,具有广泛官能团的各种苯酚和伯胺是相容的,产生结构和功能多样的苯并恶唑(64 个例子),而没有或微量观察到苯酚与胺转化的副产物。实际合成,尤其是药物 tafamidis,在通用性、选择性、效率、即使在低产量的情况下,也比传统方法具有原子经济和分步经济。从机理上讲,TEMPO 的自由基加合物与邻-cyclohexa-2,4-dien-1-one 自由基而不是公认的 cyclohexa-3,5-diene-1,2-diones 可以作为中间体。