Quaternary salts of pyrido[1,2-a]pyrimidines
Abstract
Ethyl 4-oxopyrido[1,2-a]pyrimidine-3-carboxylates undergo alkylation at the 1-position giving quaternary salts which decompose in alkaline solution yielding 2-alkylaminopyridines. Attack of the quaternary salts by ammonia occurs at the 4-position, opening the pyrimidine ring, but the 1-methyl-7-nitro-derivative is attacked at position 9a.