Pyrido pyrimi-2,4-dione

Reaction of 2-aminopyridine and 6-chloro-1,3-dipropyl-l//,3//-pyrimi-dine-2,4-dione in THE in the presence of NaH at room temperature overnight gave a mixture of 4-[A-(propylaminocarbonyl)-A-propylamino]-2//-pyrido[l,2-n]pyrimidin-2-one (349) and 6-(2-pyridylamine)-l,3-dipropyl-l//,3//-pyrimidine-2,4-dione (350, R = H) (94JHC81). Only the non-cyclized product 350 (R = Cl) was obtained from 5-chloro-2-aminopyridine. 

Cyclocondensation of ethyl 2-aminonicotinate in presence of HC(OEt)3 and various primary amines gave 22 3-substituted pyrido[2,3-,7]pyrimidin-4(377)-ones 371 <1995PHA719>. Fourteen 3,5,7-triarylpyrido[2,3-r7]pyrimi-dine-2,4(l/7,37/)-diones 372 have been prepared from the reaction of either 2-amino-3-cyano-4,6-diarylpyridines or the 3-carboxamido products of alcoholic KOH hydrolysis, with aryl isocyanates better yields were obtained from the amides <1995IJB740>. 4-Aminopyrido[2,3- pyrimidin-5(8//)-one 158 was synthesized by treatment of 2-amino-3-cyano-4-methoxypyridine with trimethylsilyl iodide to give the corresponding pyridin-4(177)-one, which was refluxed with formamidine acetate in ethoxyethanol to effect the cyclization <2000JME3704>. 

Pyrido[2,3-d]pyrimi-2,4-dione ring from / -amino-a,/ -ethyleneketones... 

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