Acetylpyran-2,6-diones: tautomeric enolic forms, spectral properties, and reactions with primary amines

The i.r., u.v., and 1H- and 13C-n.m.r. spectra of some acetylpyran-2,6-diones are discussed in relation to their tautomeric structures and compared with those of the acetylpyran-2,4-diones. Their reactions with primary amines to give Schiff bases, salts, pyridones or open-chain products as well as a thermal rearrangement of the Schiff bases are reported.