Reaction of the 3-dimethylamino-2H-azirines 1a and 1b with diphenylcyclopropenone (2a) in ether or acetonitrile leads to the 2-dimethylamino-5,6-diphenyl-4(3H)-pyridones 3a and 3b in 70 and 80% yield, respectively. The structure of these 1:1-adducts has been established by spectral data and chemical reactions. Hydrolysis of 3a yields the pyridinedione derivative 5 whereas reduction of 3a with sodium borohydride gives the dihydropyridone 6. The reaction of aminoazirine 1c, monosubstituted at C(2), with 2a gives the 4(1H)-pyridone 4. With alkyl phenylcyclopropenones (2b and 2c) aminoazirine 1a reacts to give a mixture of two isomeric 4(3H)-pyridones. The ration of the two isomers depends on the solvent.