Copper(II)-catalyzed Synthesis of Benzoxazoles from Inactive 2-chloroanilides.

Abstract

Benzoxazoles are of great importance in natural products, pharmaceutical agents as well as synthetic intermediates. Although many works on the construction of benzoxazoles by Cu-catalyzed intramolecular O-arylation of ortho-haloanilides have been reported, only a few reports about transition metal-catalyzed synthesis of benzoxazoles from inactive 2-chloroanilides so far. This work aimed to explore a green and cheap protocol for intramolecular O-arylation of inactive 2-chloroanilides to prepare 2-arylbenzoxazoles. We found that Cu(acac)2/1,10-Phen complex was beneficial to intramolecular O-arylation of 2-chloroanilides using K2CO3 as a base in EtOH at 90 °C to prepare benzoxazoles. An efficient and green method was developed for Cu(II)-catalyzed intramolecular Oarylation of inactive 2-chloroanilides. In this way, many 2-arylbenzoxazoles were prepared in good yields.