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

Abstract

Aim and Objective: Benzoxazoles are of great importance in natural products, phar-maceutical 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. Materials and Methods: We found that Cu(acac)2/1,10-Phen complex was beneficial to intra-molecular O-arylation of 2-chloroanilides using K2CO3 as a base in EtOH at 90 oC to prepare benzoxazoles. Results: An efficient and green method was developed for Cu(II)-catalyzed intramolecular O-arylation of inactive 2-chloroanilides. Conclusion: In this way, many 2-arylbenzoxazoles were prepared in good yields.