Merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the environmentally friendly synthesis of 2-aminobenzoxazoles
Merging the ring opening of benzoxazoles with secondary amines and an iron-catalyzed oxidative cyclization towards the environmentally friendly synthesis of 2-aminobenzoxazoles
作者:Daqian Xu、Wenfang Wang、Chengxia Miao、Qiaohong Zhang、Chungu Xia、Wei Sun
DOI:10.1039/c3gc41206g
日期:——
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.
A Metal-Free Route to 2-Aminooxazoles by Taking Advantage of the Unique Ring Opening of Benzoxazoles and Oxadiazoles with Secondary Amines
作者:Jomy Joseph、Ji Young Kim、Sukbok Chang
DOI:10.1002/chem.201100910
日期:2011.7.18
Toss an amine into the ring: A new metal‐free protocol for the amination of oxazoles has been developed by using iodobenzene diacetate to couple various oxazoles with amines (see scheme). The reaction proceeds through a ring‐opening and subsequent ring‐closing pathway. The optimal conditions are very mild and the substrate scope is broad, producing a range of 2‐aminooxazoles, an important pharmacophore
N-Bromosuccinimide as an oxidant for the transition-metal-free synthesis of 2-aminobenzoxazoles from benzoxazoles and secondary amines
作者:Xiaoe Wang、Daqian Xu、Chengxia Miao、Qiaohong Zhang、Wei Sun
DOI:10.1039/c4ob00386a
日期:——
A facile and transition-metal-free method was developed through merging the ring opening of benzoxazoles with secondary amines and N-bromosuccinimide (NBS) mediated oxidative cyclization toward the synthesis of 2-aminobenzoxazoles. NBS was selected as a powerful oxidant in the oxidative cyclization of ring-opening amidines to provide the desirable 2-aminobenzoxazoles in excellent yields (up to 94%).
Hemoglobin: A New Biocatalyst for the Synthesis of 2-substituted Benzoxazoles<i>via</i>Oxidative Cyclization
作者:Fengxi Li、Zhengqiang Li、Xuyong Tang、Xinyu Cao、Chunyu Wang、Jialin Li、Lei Wang
DOI:10.1002/cctc.201801760
日期:2019.2.20
Efficient and mild synthesis of a series of 2‐substituted benzoxazoles via oxidativecyclization catalyzed by hemoglobins reported here for the first time. Satisfactory yields (84 %–97 %) and mild reaction conditions make this method highly viable for practical applications.