From 4-Pyrans
γ-Pyran
5,6-DIHYDRO-2H-PYRAN-2-ONE AND 2H-PYRAN-2-ONE
2-Pyran-2-thiones
2-Pyran-2-ones
3,6-Dihydro-2-pyrans
Studies in pyrane chemistry
From 2-Pyran-2-ones or 4-Pyran-4-ones and Ammonium Salts