Hemicryptophane-oxidovanadium(V) complexes: Lead of a new class of efficient supramolecular catalysts

Hemicryptophane-oxidovanadium(V) complexes 1 and 2 were tested in the oxidation of sulfide to sulfoxide. They were found to be efficient supramolecular catalysts in the oxidation of thioanisol with yields up to 95%. Furthermore, turnover up to 180 was obtained by decreasing the amount of catalyst to 0.5% molar. A direct comparison between hemicryptophane complexes 1 and 2 and the model complex 3, which lacks a cavity, was made. The cage structure in 1 and 2 strongly enhanced the catalytic activity, and higher yields were obtained with 1 or 2 than with the model compound 3. Kinetic constants for the oxidation of thioanisol were estimated up to sixfold higher with the hemicryptophane complexes than with the model complex 3. (C) 2009 Elsevier Inc. All rights reserved.