ENAMINO ESTERS IN THE SYNTHESIS OF HETEROCYCLIC SYSTEMS. TRANSFORMATION OF DIMETHYL ACETONE-1,3-DI-CARBOXYLATE INTO POLYSUBSTITUTED 1,6-NAPHTHYRIDINE-8-CARBOXYLATES

摘要

A simple two-step synthesis of 1,6-naphthyridine derivatives is described. Methyl 2-(2-methoxy-2-oxoethyl)-6-oxo-1,6-dihydropyridine-3-carbo-xylate (3), prepared from dimethyl acetone-1,3-dicarboxylate (1) and propyolic acid amide (2) according to the known procedure, was transformed with N,N-dimethylformamide dimethyl acetal (DMFDMA) first into 2-[1-(dimethylamino)-3-methoxy-3-oxoprop-1-en-2-yl]-6-oxo-1,6-dihydropyridin e-3-dicarboxylate (4). This was followed by reaction with monosubstituted hydrazines 5a-h to afford substituted l,6-naphthyridine-8-carboxylates 7a-h.