Abstract
Attempts to prepare 5-oxothiopyrano [2, 3-d] pyrimidine derivatives by the reaction of 6-mercapto-1, 3-dimethyluracil (I) with various acetylenecarboxylates and ethyl ethoxymethylenecyanomalonate have led instead to the synthesis of substituted thiopyrimidine-2, 4-dione. the condensation of (I) with diethyl ethoxymethylenemalonate yielded readily the corresponding 5-oxothiopyrano [2, 3-d] pyrimidine-2, 4-dione. Elimination of ethoxycarbonyl group in V obtained 1, 3-dimethyl-5-oxothiopyrano [2, 3-d] pyrimidine-2, 4-dione.
