5- tetrahydropyrimidine-4,6-dione

Methoxyphenoxy)-2-(pyrimidin-2-yl)tetrahydropyrimidine-4,6-dione 4,6-Dichloro-5-(2-methoxyphenoxy)-2,2 -bipyrimidine 4-t-Butyl-N-[6-chloro-5-(2-methoxyphenoxy)-2-(pyrimidin-2-yl)-pyrimidin-4-yl] benzenesulfonamide... 

Tritylation at the primary hydroxyl group in l-(5-trityl-D-ribofur-anosyl)-l,2,3,4-tetrahydropyrimidine-2,4-dione (monotrityluridine) was established by Levene and Tipson. The two free hydroxyl groups were first esterified with p-toluenesulfonic acid. Since the trityl-ditosyl compound thus formed did not react with sodium iodide " it did not contain a primary tosyl group. Therefore, tritylation had occurred at the primary hydroxyl group. 

Thus, in base-catalyzed reactions of l,3-dimethyl-2,4-dioxo-l,2,3,4-tetrahydropyrimidine-5-carbonitrile with acetonitrile, malononitrile or similar compounds,192,278,279 as well as ketones,277 pyrido[2,3-c/]pyrimidine-2.4(1 //,3//)-diones 1 retaining the urea portion are formed. 

Reaction of cycloalkenyl-1-diazenes 116 with tetrahydropyrimidine-2-thione (Scheme 52) in methanol at room temperature give thiazolo[3,2-a]pyrimidine]-2,3 -dione- 2-semicarbazones 118 via the intermediate 117 [78]... 

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