3-Cyano-2-(phenylethynyl)pyridine (1) was cyclized intramolecularly under acidic conditions to give 1,6-naphthyridin-5(6H)-one (2) and 5H-pyrano[4,3-b]pyridin-5-one (4). Pyranopyridine 4 was readily transformed to 2 or naphthyridinone 9 having an alkyl substituent at 6-position.