Sustainable synthesis of heteroaryl ethers from azine N-oxides via phosphoramide catalysis

Abstract

A rapid and eco-friendly approach has been devised for synthesizing heteroaryl ethers. This methodology involves the reaction between nitrogen heteroaromatic N-oxides and phenol derivatives or alcohols, catalyzed by an in situ generated phosphonium salt. This salt acts as the activating agent and is formed through the reaction of the byproduct phosphoramide with phosphoryl tribromide. Compared to previously reported methods, this method stands out due to its excellent atom economy (92%), the obviation of C1- or C2-prefunctionalized heteroaromatics, the use of an eco-friendly solvent, mild reaction conditions, the incorporation of feedstock materials as catalysts, a short reaction time, and a broad substrate scope, yielding a diverse array of heteroaryl ethers.