Synthesis of new 5-hydroxyquinazoline derivatives from functionalized 5-acetyl-6-methylpyrimidines

A new method for the synthesis of quinazolines based on the annulation of the benzene ring to 5-acetyl-6 methylpyrimidin-2-one(thione) derivatives has been proposed. Condensation of the latter at the methyl group with dimethylformamide dimethyl acetal in boiling PhH leads to the formation of 5-acetyl-6-[2-(dimethylamino)vinyl]pyrimidin-2-ones(thiones), which, when boiled with MeONa in MeOH, cyclize to 5-hydroxyquinazolin-2-ones(thiones). Similarly, 5-acetyl-6-methyl-4-(trifluoromethyl)pyrimidine was converted to 5-hydroxy-4-(trifluoromethyl)quinazoline. Quinazolines are not formed from 5-acetyl-6-methylpyrimidines condensed with dimethylformamide dimethyl acetal at the acetyl group, but 5-acetyl-6-methylpyrimidines can be used to obtain pyrido[2,3-d] pyrimidine derivatives.