The fate of carbonyl-¹⁸O in the rearrangement of an acyloxycarbene to a 1,2-dione

Abstract

5-[carbonyl-¹⁸O]Benzoyloxy-2,2,5-trimethyl-1,3-dioxan-4,6-dione (1) was prepared by benzoylation of 5-hydroxy-2,2-dimethyl-1,3-dioxan-4,6-dione with [¹⁸O]benzoyl bromide followed by C-methylation.Flash vacuum pyrolysis of(1) at 560º/0.01 mm gave 1-phenyl[1-¹⁸0]propane-1,2-dione. The position of the label was determined by infrared and mass spectrometry. Scrambling of oxygen to the2-carbonyl group was negligible.