A facile and environmentally friendly method was developed through merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the synthesis of 2-aminobenzoxazoles. In the oxidative cyclization step, with catalytic amounts of FeCl and aqueous H2O2 as a green oxidant, highly desirable 2-aminobenzoxazoles were isolated in excellent yields of up to 97%. A plausible radical process is proposed for the oxidative cyclization on the basis of mechanistic studies.
开发了一种简便且环境友好的方法,通过将
苯并恶唑与二级胺的开环反应与
铁催化的氧化环化反应相结合,用于合成2-
氨基
苯并恶唑。在氧化环化步骤中,使用催化量的FeCl和作为绿色氧化剂的
过氧化氢水溶液,可以高效地分离出高达97%收率的理想2-
氨基
苯并恶唑。基于机理研究,提出了一个可能的自由基过程作为氧化环化反应的机制。