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.