Condensed Heteroaromatic Ring Systems. III. Synthesis of Naphthyridine Derivatives by Cyclization of Ethynylpyridinecarboxamides

Abstract

Four kinds of naphthyridinones, i.e. 1, 6-naphthyridin-5-one, 1, 7-naphthyridin-8-one, 2, 6-naphthyridin-2-one, and 2, 7-naphthyridin-1-one derivatives, were commonly synthesized by the intramolecular cyclization of pyridinecarboxamides having an ethynyl group or β, β-dimethoxyethyl group adjacent to the carbamoyl group. The syntheses of the starting pyridine derivatives were easily accomplished by cross-coupling of the corresponding halopyridines with acetylenes.