Novel alkylations of cyclic thioureas by α-halocarboxylic acids and their esters. 4. Alkylation of 1-methyltetrahydropyrimidine-2(1H)-thione

Alkylation of 1-methyltetrahydropyrimidine-2(1H)-thione (N-methylpropylenethiourea) with chloro-and bromoacetic acids and their esters have given the 8-methyl-3-oxo-2,3,6,7-tetrahydro-5H-[1,3]thiazolo[3,2-a]pyrimidin-8-ium chloride or bromide. The former is readily hydrolyzed in 95% ethanol to 3-[(3-methylamino)propyl]-1,3-thiazolidine-2,4-dione hydrochloride while the second is more stable towards hydrolysis such that the corresponding hydrobromide is not separated. A paradoxical trend in the extent of the hydrolysis decreasing with the content of the water in the alcoholic solution comes to a complete stop in water. A possible explanation of this phenomenon is given. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1242–1251, August, 2006.