The catalytic oxidation of epoxides to α α α α α-diketones provides a novel access to a variety of flavouring compounds and odorants. This alternative synthetic strategy involves an oxidation reaction catalysed by commercially available reagents and affords four cyclic and acyclic α α α α α-diketones presenting interesting organoleptic properties. ). α-Diketones also constitute useful intermediates for the synthesis of alkylpyrazines, a class of nitrogen-containing heterocycles used for their roasted nut notes, formed by the condensation of α-diketones with diamino compounds and subsequent dehydrogenation reaction.9 Applications of α-diketones as deodorants have been also reported. 10Some α-diketone syntheses applied to flavouring compounds involve the acid-catalysed rearrangement of the corresponding α,β-epoxyketones, 11 oxidation 12 or electrooxidation 13 of alkynes, or halogenation of carbonyl compounds followed by acidic hydrolysis.14 In this paper, we present our results concerning the alternative synthesis of useful flavouring α-diketones from the one-pot oxidation of the corresponding epoxides, in a catalytic system based on the use of bismuth and molecular oxygen in DMSO. Experimental GCGC analysis were carried out using a Hewlett-Packard 6890N gas chromatograph with two FID detectors, under the following conditions: vector gas, He; injector and detector temperatures, 250°C; split ratio, 1:50; constant flow, 1 ml/min; HP1 column, polydimethylsiloxane (50 m × 0.20 mm i.d., film thickness 0.33 µm) and INNOWAX column, polyethyleneglycol (50 m × 0.20 mm i.d., film thickness 0.2 µm); temperature programme, 60-250°C at 2°C/min and 250°C for 10 min. Retention indices were determined using C 5 -C 28 alkane standards as reference.