The tautomerism of pyrimidine bases was applied to a new type of polymer synthesis that was achieved by the dehydrochlorination of dichloropyrimidines with diols to give polyethers containing a 2,4-pyrimidine structure in the main chain. The polymer decomposed to uracil or thymine under an acidic condition but not under a basic condition. A degradation based on tautomerism could be useful far a new kind of degradable polymer synthesis and polymer drug-delivery system.