Pyrido pyriinidin-7-ones

A series of 2,3-disubstituted pyrido[4,3-d]pyriinidin-4(3Zf)-ones (154) showed more complicated fragmentation patterns. Here again, however, strong molecular ions were invariably present and m/2e peaks were common, as were M-1 peaks. The nature of the group Rj... 

Suitable cyclization partners are 2-(acylamino)nicotinic acids and primary amines, giving 2,3-disubstituted pyrido[2,3-r7]pyriinidin-4(3//)-ones. Thus, 3-aryl-2-methylpyrido[2,3-c/]pyrimidin-4(3/f)-ones 22 are synthesized by fusion of 2-acetamidonicotinic acid with arylamines.33... 

Pyridyl)pyrido[2,3-[Pg.116]

Ethyl 2-methyl-5-(phenylethynyl)pyriinidine-4-carboxylate, obtained by palladium-mediated coupling, cyclizes with ammonia at 120 °C to give 2-methyl-6-phenylpyrido[3,4-d]pyrimidin-8(7//)-one.139 This reaction is similar to the one used in the pyrido[4,3-rf]pyrimidinc series (see Section 7.2.2.4.1.1.4.). 

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