57. SYNTHESIS, PROTONATION, AND ACID-BASE PROPERTIES OF CONDENSED DERIVATIVES OF 4-OXO-1,4-DIHYDRO-1,8-NAPHTHYRIDINE

Article abstract of DOI:10.1007/BF00487431

A number of 4-oxo-1,4-dihydro-1,8-naphthyridine derivatives that differ with respect to the sizes of the aza- and carbocycles were synthesized by the reaction of 3-amino-4-ethoxycarbonyl-5,6,7,8-tetrahydroisoquinoline with N,N-dimethylacetamide diethylacetal and subsequent cyclization of the intermediate amidines.It was established by UV and 1H and 13C NMR spectroscopy that the protonation of these compounds takes place at the exocyclic oxygen atom.The dependence of the ionization constants of the compounds obtained in 70 percent DMFA on the size of the saturated cyclic fragments of the molecules was established.