NOVEL HETEROCYCLIC SYSTEMS. PART 7. NEW SPECIES CONTAINING TWO PYRIDINE RINGS BY DEHYDRATION OF 3-HYDROXY-2(1H)-PYRIDONE USING PHOSPHORUS PENTOXIDE.
Dimeric dehydration products of 3-hydroxy-2(1H)-pyridone (1) are obtained by melting a mixture of (1) and P2O5 at 250-290 deg C.The major product is 3-hydroxy-1-(3-hydroxy-2-pyridyl)-2(1H)-pyridone (7).Also obtained are 1,6-diazaphenodioxin (5) and a novel betaine, 6-oxidodipyridooxazolium (6).
Matthews, Ian,Smith, Keith,Turner, John R.,Martin, Gary E.