Effective esterification of carboxylic acids using (6-oxo-6H-pyridazin-1-yl)phosphoric acid diethyl ester as novel coupling agents

Abstract (6-Oxo-6 H -pyridazin-1-yl)phosphoric acid diethyl esters ( 3 ) are efficient and selective coupling agents for equimolar esterification of carboxylic acids and alcohols. Esterification of aliphatic and aromatic carboxylic acids with aliphatic and aromatic alcohols using 3 afforded the corresponding esters chemoselectively in good to excellent yield.