Mild and Efficient Synthesis of Carboxylic Acid Anhydrides from Carboxylic Acids and Triazine Coupling Reagents

Abstract

Anhydrides of carboxylic acids were obtained in 53%–95% yield by treatment of appropriate carboxylic acids with 2‐chloro‐4,6‐dimethoxy‐1,3,5‐triazine (CDMT) or 2,4‐dichloro‐6‐methoxy‐1,3,5‐triazine (DCMT) in the presence of N‐methylmorpholine. It has been proved that synthesis proceeds via triazine active esters 3a,b, which are able to acylate carboxylate anion but not less nucleophilic carboxylic acid.