Alcohol Oxidation by Dioxygen and Aldehydes Catalysed by Square-Planar Cobalt(III) Complexes of Disubstituted Oxamides and Related Ligands

✍ Scribed by Isabel Fernández; José R. Pedro; Antonio L. Roselló; Rafael Ruiz; Isabel Castro; Xavier Ottenwaelder; Yves Journaux

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 397 KB
• Volume: 2001
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/1099-0690(200104)2001:7<1235::aid-ejoc1235>3.0.co;2-4

✦ Synopsis

The square-planar cobalt(III) complexes of o-phenylenebis(NЈ-methyloxamidate) (Me 2 opba) and related oxamate (Meopba) and bis(oxamate) (opba) ligands catalyse the selective oxidation, by dioxygen and pivalaldehyde, of a wide range of secondary alcohols to the corresponding ketones, in good yields and under mild conditions in acetonitrile at room temperature. Thus, the oxidation of the series of α-alkylbenzyl alcohols PhCH(OH)R (R = Me, Et, iPr, tBu) results in the exclusive formation of ketones as a product of C-H bond cleavage, and no C-C bond cleavage products are observed in any case. The modulation of catalytic activity by ligand substituents among this series of cobalt catalysts highlights the role of oxocobalt(IV) species as the putative inter- [a]