Aldehyde deformylation reactions by metal dioxygen adducts have been proposed to involve peroxyhemiacetal species as key intermediates. However, direct evidence of such intermediates has not been obtained to date. We report the spectroscopic characterization of a mononuclear cobalt(III)-peroxyhemiacetal complex, [Co(Me 3 -TPADP)(O 2 CH(O)CH(CH 3 )C 6 H 5 )] + ( 2 ), in the reaction of a cobalt(III)-peroxo complex ( 1 ) with 2-phenylpropionaldehyde (2-PPA). The formation of 2 is also investigated by isotope labeling experiments and kinetic studies. The conclusion that the peroxyhemiacetalcobalt(III) intermediate is responsible for the aldehyde deformylation is supported by the product analyses. Furthermore, isotopic labeling suggests that the reactivity of the cobalt(III)-peroxo complex depends on the second reactant. The aldehyde inserts between the oxygen atoms of 1 , whereas the reaction with acyl chlorides proceeds by a nucleophilic attack. The observation of the peroxyhemiacetal intermediate provides significant insight into the initial step of aldehyde deformylation by metalloenzymes.

This paper provides the first report of the snail-killing fly genus Dichetophora Rondani, 1868 on the Korean peninsula with the discovery of two new species, D. koreana sp. nov. and D. nigricorpa sp. nov. Descriptions and illustrations of the new species and keys to the Palearctic species of this genus are given.

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