The general procedure for the synthesis of 2-(2-hydroxyethoxy)ethyl 4-methylbenzenesulfonate from p-toluenesulfonyl chloride and diethylene glycol was as follows: first, the diethylene glycol was protected with a monohydroxy group. This was done as follows: in a dichloromethane solvent, potassium iodide (0.2 eq.) was added as a catalyst, followed by freshly prepared silver oxide (1.5 eq.) and p-toluenesulfonyl chloride (1.1 eq.). The reaction mixture was stirred at room temperature for 8-10 h. Upon completion of the reaction, mono-p-toluenesulfonyl-protected diethylene glycol was obtained in 97-99% yield. This step provides a selectively protected intermediate for the subsequent reaction with aconitic acid.
