Polymer-supported 1,3-dimethyl-2-imidazolidinone (1), is converted to the dehydrating agent 2 upon chlorination with oxalyl chloride. The chloro compound 2 is a very active esterification agent, and hindered compounds such as pivalic acid or tert-butyl alcohol are converted to esters in good yield. After the reaction, 1 is easily recovered through filtration and reused repeatedly. This method, developed by Ishikawa and co-worker, is expected to be an environmentally friendly dehydration condensation method.