Metal-Free Formation of 2-Substitued Benzoxazoles with Amides and Esters

2-Substituted benzoxazoles are important heterocyclic motifs due to their wide application in pharmacology. A PCl3-mediated C(2)-functionalization of benzoxazole derivatives with inert amides and esters under metal-free conditions was reported. By using PCl3/I-2 combination, various 2-substituted benzoxazoles could be synthesized via the arylation or alkylation of benzoxazoles with amides and esters in the presence of water. What's more, the reactivity between amides and esters was also investigated. The primary results indicated that amides have higher reactivity than esters under this system. This method features a broad substrate scope, simple condition and low-cost. A plausible mechanism was also proposed.