Isoxazolo pyrimidine-4,6-diones

Isoxazolo[5,4-d]pyrimidine, 4-hydroxy-3-methyl-UV, 6, 620 <64JOC2116) Isoxazolo[5,4-d]pyrimidine, 3-methyl-4-(methylamino)-UV, 6, 620 <64JOC2116) Isoxazolo[5,4-d]pyrimidine, 3-phenyl- H NMR, 6, 619 <77H(7)51) Isoxazolo[3,4-d]pyrimidine-4,6(5//,7W)-dione, 5,7-dimethyl-... 

Little has been discussed on this topic in CHEC-II <1996CHEC-II(7)431>. The isoxazolo[4,5- / pyrimidin-3,7-diones 185 or 186 are converted into 187 upon oxidation with potassium permanganate in acetone (Scheme 8) <2004BMC265>. 

The ring opening of the isoxazole part of isoxazolo[3,4-malonic acid derivatives (XCH2Y) is supposed to give the corresponding (l,2,3,4-tetrahydro-6-(hydroxyamino)-l,3-dimethyl-2,4-dioxopyrimidin-5-yl)methylenemalonic acid derivatives, which cyclize via one of the groups X or Y to yield l,3-dimethylpyrido[2,3-d]-pyrimidine-2,4(1 /f,3//)-dione 8-oxides.306... 

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