Naphthyridine studies. 15. 2-Styrylquinoline-3-carboxamides and their cyclization to 3-aryl-1-oxo-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridines
Condensation of 2-methylquinoline-3-carboxamides or the acid nitrile with benzaldehydes gave 2-styrylquinoline-3-carboxamides or the nitrile. It was shown that these compounds cyclize to the 2-substituted 3-aryl-1-oxo-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridines using pofyphosphoric acid or sulfuric acid.