-The asymmetric vanadium-catalyzed oxidation of alkyl aryl sulfides is optimized using a Schiff base ligand, readily prepared from 3,5-diiodo-salicylaldehyde. The use of polymer-supported ligands leads to a loss of enantioselectivity. Best results are obtained with ligands (I)-(III).

A novel family of chiral acylation catalysts based on a N-4'-pyridinyl-alpha-methyl proline structure has been studied. A set of 31 compounds has been easily prepared and screened in the kinetic resolution of racemic alcohol 33 resulting in high enantioselectivities in most cases. From results obtained, H-bonding interactions between the catalyst and the substrate would appear essential to afford high enantioselectivity during the catalytic acylation. Additional solvent dependence and anhydride studies have been made to better identify the mechanism. This work has been further extended to the study of a number of structurally different alcohols. Ethanolamine derivatives in particular were found to be highly effective substrates (up to S = 18.8) in the kinetic resolution.

No abstract

No abstract