Catalytic oxidative carbon-carbon bond cleavage of ketones with dioxygen:: assessment of some metal complexes.: Some alternatives for preparing α, ω-dicarboxylic acids

This account considers the catalytic oxidative cleavage of ketones with dioxygen. It can be brought about by Keggin-type heteropolyanion complexes containing molybdenum and vanadium as well as by several transition metal catalysts (V(IV, V), Cu(I, ID, Fe(III), Ce(IV), etc.), instead of using stoichiometric oxidation with periodate, lead tetra-acetate, etc. Benzylic ketones, ArCH(2)C(O)R are oxidised to ArCHO and the corresponding carboxylic acid in high yield at room temperature by dioxygen in the presence of Cu(II) or heteropolyacids H(3+n)[PMo(12-n)V(n)O(40)](aq), Although some oxovanadium complexes will induce such oxidations, the heteropolyacids are better, probably due in parr to their Bronsted acidity and ability to take parr in a variety of equilibria. Treatment of substituted cycloalkanones with a catalytic amount of H(5)[PMo(10)V(2)O(40)].n H(2)O' (or Cu(II) complexes) under an O(2) atmosphere gives keto-acids in good yield. The selectivities observed at high conversions with various ketones and diols coupled with the mild conditions and inexpensive oxidant, would seem to make these methods attractive for use in fine chemical manufacture. The scope of these complexes as selective oxidation catalysts can be further extended by associating several metal ions. Such catalysts are being developed for organic synthesis at both the laboratory and industrial scale. Alternative routes to adipic acid involving cyclohexanone, cyclohexene, cyclohexane, etc. and polyoxo(peroxo)metalates or redox molecular sieves as liquid-phase oxidation catalysts, are compared. Alternatives, both biochemical and chemical, are being sought. (C) 2001 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.