Decomposition of α-diazo-ketones: the oxiren–oxocarbene equilibrium

Abstract

A sensitive chemical test for the participation of oxirens in the decomposition of diazo-ketones has been developed, based on the subsequent rearrangement of oxocarbenes to αβ-unsaturated ketones. In this way oxiren participation has been demonstrated in the thermal and photochemical decomposition of a variety of diazo-ketones, including 3-diazoheptan-4-one, 1-diazo-3-phenylpropan-2-one, and 2,2-dimethyl-4-diazohexan-3-one. In contrast, no oxiren participation occurred in the catalysed decomposition of the diazo-ketones with either silver or copper oxide. The importance of competing processes, such as the Wolff rearrangement, is also discussed.