A NOVEL THIAZOLE SYNTHESIS . 4,5,6,7-TETRAHYDROTHIAZOLO[4,5-D]PYRIMIDINE-5,7-DIONES

6-Amino-1,3-dimethyluracils (1, R = H, COOH, COOC2H5, C6H5, and CF3) have been found to undergo facile conversion to the corresponding thiazolopyrimidines (2) upon treatment with thionyl chloride-pyridine, except for 1, R = CF3, where thionyl chloride is more effective in the absence of pyridine. Thiazolopyrimidines (2, R = H, COOH, and COOC2H5) have been reported previously by Schroeder.2 The reaction is presumed to proceed via dehydration of the intermediate thiazoline S-oxides (6). A different reaction is observed when an inferior grade of thionyl chloride is used in the absence of pyridine, resulting in the formation of sulfides (8) and products derived therefrom. Speculation is offered on the mechanism of thiazole formation from suitably substituted 6-aminouracils. © 1969, American Chemical Society. All rights reserved.