Cobalt (II) Schiff base catalyzed aerobic oxidation of secondary alcohols to ketones

A variety of secondary alcohols were efficiently oxidized to corresponding ketones in excellent yields with molecular oxygen using cobalt (II) Schiff base complexes as catalyst. In general, alcohols having a carbonyl moiety at their ∝-position were found to be more reactive and required lesser reaction time for their oxidation. While benzoins showed higher reactivity as compared to the acyloins, among the benzoins those having electron-donating groups were found to be more reactive. Among the various cobalt Schiff base complexes studied, bis[2-[{1-phenylethyl)imino} methyl] phenolato-N,O]-cobalt (1) was found to be most efficient catalyst for this transformation. Keywords: Cobalt Schiff base complexes; Secondary alcohols; Ketones; Oxidation; Molecular oxyge