TRANSFORMATIONS OF DIETHYL 2-(DIMETHYLAMINO)METHY- LENE-3-OXOPENTANEDIOATE. A SIMPLE SYNTHESIS OF SUBSTITUTED 2-AMINO-5-OXO-5,6-DIHYDROPYRIDO4,3-dPYRI- MIDINE-8-CARBOXYLATES

摘要

Diethyl 2-(dimethylamino)methylene-3-oxopentanedioate (2), prepared from acetone-1,3-dicarboxylates (1) and N,N-dimethylformamide dimethyl acetal (DMFDMA) was, without isolation, transformed by treatment with guanidine hydrochloride into ethyl 2-amino-4-(2-ethoxycarbonylmethyl)-pyrimidine-5-carboxylate (3). Compound 3 was transformed with DMFDMA first into intermediate 4 and with an excess of DMFDMA into ethyl 4- 1 -(dimethylamino)-3-ethoxy-3-oxoprop-1 -en-2-yl-2-(dimethylamino)methyle neaminopyrimidine-5-carboxylate (5). By treatment of compound 5 with ammonia, primary amines, hydrazine or hydroxylamine intermediates 6a-j were formed, which cyclized into 6-substituted 2-amino-5-oxo-5,6-dihydro-pyrido4,3-dpyridine-8- carboxylates (7a-j).