Pyrido purine-2,4-dione

Priego EM, von Frijtag Drabbe Kuenzel J, Ijzerman AP, Camarasa MJ, Perez-Perez MJ (2002) Pyrido[2, l-f]purine-2, 4-dione derivatives as a novel class of highly potent human A3 adenosine receptor antagonists. J Med Chem 45 3337-3344... 

The syntheses of 1,3-dipropyl-l//,3//-pyrazino-, pyrid0 5 pynmido-, and pyrrolo[2,1 /]purine-2,4-diones starting from 5,6-diamino-l,3-dipropylpyrimidine-2,4-dione and 6-chloro-l,3-dipropyl-pyrimidine-2,4-dione have been described (Scheme 15) <94JHC8l>. A new route to 1,3-dipropyl-1H, 3/f-pyrido- (or pyrazino-) [T,2 -l,2]pyrimidino[4,5-d]pyrimidino-2,4,5-triones has also been developed (Scheme 16). 

Dealkylation, of azolium quaternary salts and betaines, 60, 244 Deazaflavines, bent, 55, 192 5-Deazalumazines, see Pyrido[2,3-(/]pyrimidine-2,4-diones Deaza-purines, -flavines, etc., see the systematically-named ring systems 4-Deazatoxoflavins, syntheses, 55, 182 Dechlorination, catalytic, of chloro-[ 1,2.4]triazolo[ 1,5-a]pyrimidines, 57, 125... 

Fusion of imidazo[4,5-/]pyrido[2,l-6][l,3,5]oxadiazocine-5,12-dione (85) at 220-230°C results in ring contraction with elimination of carbon dioxide to produce the pyrido[2,l-/]purine (86), as shown in Equation (2) <82CPB3088>. 

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