New poly (oxyethylene) derivatives from Diels-Alder reactions of 3-[methoxypoly(oxyethylene)]methylene furan

A new poly(ethylene glycol) derivative, 3-[methoxypoly(oxyethylene)]methylene furan, 1, was prepared from the reaction of 3-furanmethanol with the mesylate of methoxypoly(oxyethylene) in tetrahydrofuran. The degree of end-group conversion, as determined by NMR spectroscopy, was 100%. The Diels-Alder reactions of I with N-phenylmaleimide, N-glycinylmaleimide, maleic anhydride, N,N'-hexamethylene bismaleimide, and diethyl acetylenedicarboxylate resulted in the corresponding adducts. For the adduct derived from I and N-phenylmaleimide, its thermal reversible character was confirmed by applying a retro-Diels-Alder reaction in the presence of a large excess of 2-methylfuran, which restored the initial polymer,1 quantitatively. The adduct obtained from I and N-glycinylmaleimide was converted into its succinimidyl ester and its hydrolysis rate in phosphate buffer (pH = 8) was determined. The reactivity of the adduct derived from I and N,N'-hexamethylene bismaleimide with benzyl mercaptan was also investigated.