TMSCl Promoted Direct Conversion of Cyclic Anhydrides to (Un)Symmetric‐Diesters/Amide Esters

Abstract

AbstractWe present a mild, efficient, and one‐pot method for the silyl‐promoted transformation of cyclic anhydrides into homo‐ and hetero‐dicarboxylic acid diesters and amide esters. This versatile reaction operates under ambient conditions, on a gram scale, and accommodates a wide range of alcohols, amines, and cyclic anhydrides. The one‐pot process involves a two‐step sequence, starting with the nucleophilic opening of anhydride by an amine or alcohol, followed by esterification. TMSCl serves a dual role, acting as a sacrificial reagent to remove in situ water and as a Lewis acid to promote the anhydride opening. The reaction proceeds successfully in the absence and presence of a base, as confirmed by NMR and crossover experiments, which validated the formation of dicarboxylic acid monoester and alkyl silyl mixed diester respectively. Controlled experiments have shown that the one‐pot process yields higher efficiencies when compared to the same reaction conducted using a two‐step process. This is the first comprehensive study demonstrating a broad substrate scope for the conversion of cyclic anhydride into diesters and amide esters. The method finds application in the synthesis of various commercial plasticizers.