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Paper | Special issue | Vol 77, No. 2, 2009, pp.899-908
Published online, 25th September, 2008
DOI: 10.3987/COM-08-S(F)90
Transformations of Diethyl 2-[(Dimethylamino)methylene]-3-oxopentanedioate. A simple Synthesis of Substituted 2-Amino-5-oxo-5,6-dihydropyrido[4,3-d]pyrimidine-8-carboxylates

Silvo Zupancic, Jurij Svete, and Branko Stanovnik*

*Department of Organic Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, P.O. Box 537, SI-1000 Ljubljana, Slovenia


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)methyleneamino]pyrimidine-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-dihydropyrido[4,3-d]pyridine-8- carboxylates (7a-j).