Synthesis, spectroscopic properties, and chemistry of 4,6-diphenyl-2-pyridones and 4,6-diphenylpyridine-2-thiones and their relationship to isomeric species

Abstract

4,6-Diphenylpyran-2-imines (9) are rearranged by sodium ethoxide to the isomeric 2-pyridones (10), but the corresponding thiopyran-2-imines (21) do not rearrange to pyridine-2-thiones (25). The conversion (10)→(25) is effected by phosphorus pentasulphide. Certain pyridine-2-thiones (25) rearrange to 2-arylthiopyridines (27) on heating. The isomeric compounds are readily distinguished by their mass spectra; n.m.r., u.v., and i.r. spectra are discussed.