Facile and environmentally benign synthetic approach to the selective mono-chlorination and mono-bromination of benzo[d]OXAZOL-2(3H)-ONES

Exhibiting a wide spectrum of practical applications, benzo[d]oxazol-2(3H)-ones (BOA) are considered as key intermediates in the synthesis of pharmaceutical products, organic dyes, and OLED materials among others. Herein, we propose an environmentally benign protocol for the selective mono-halogenation of benzo[d]oxazol-2(3H)-ones. Several chloro- and bromo-substituted BOA derivatives were prepared within less than an hour with high to excellent yields (75%-93%) via this novel, green, and energy sufficient method. This rapid and highly reproducible synthetic approach employs inexpensive commercially available urea-hydrogen peroxide complex and hydrochloric or hydrobromic acid. Simple operations and precise control over the oxidative halogenation, with water being the major by-product of the reaction outcome, are among the strong point of current facile method from the perspective of green chemistry.