Useful Reagent for Condensation Reaction

2-Methyl-6-nitrobenzoic anhydride (1) is a dehydrating reagent developed by Shiina et al., used for the synthesis of carboxylic esters from nearly equimolar amounts of carboxylic acids and alcohols.¹⁾ Esterification reactions using 1 proceed under basic to neutral conditions, resulting in carboxylic esters which are obtained in excellent yields with high chemoselectivities. This reagents versatility is further exemplified in it's application to the synthesis of lactones.²⁾