Selective oxidation of alcohols promoted by cis-Dioxomolybdenum (VI) ONO Complexes

Selective oxidation of alcohols to aldehydes in mild conditions remains an important reaction in organic synthesis, in this regard the use of molybdenum complexes of Schiff bases results in an effective improvement of the catalysis of this reaction. Several ONO Schiff bases were synthesized by condensation of o-aminophenol and the corresponding 5-substituted salicylaldehyde derivatives, further complexation with bis(acetylacetonato)dioxomolybdenum(VI) afforded the corresponding cis-dioxomolybdenum(VI) complexes which were fully characterized. These complexes were used as catalysts for the oxidation of several alcohols under solvent-free condition using H2O2 as oxidant with outstanding results. The electronic effects of the substituents in the catalytic process were studied concluding that strong electron withdrawing groups indeed facilitates the catalytic reaction. Furthermore, the scope of the methodology was evaluated showing good tolerance to other functional groups.