Phenacyl azide (Ia) and structurally related a-azido-ketones (10, c, d) underwent the loss of nitrogen when heated between 180 and 240" in an inert solvent. Good yields of the corresponding imidazoles (IIIa, b, e, d) resulted from dimerization and dehydration of the postulated a-imino-ketone intermediate. Both triazoacetone (I, R= CHa-) and l-azido-3, 3- dimethylbutanone-:!(I, R=(CHz), C-) underwent the loss of nitrogen when heated between ...