New ligands for asymmetric dihydroxylation: multiple cinchona alkaloid units attached to a central heterocyclic core

Abstract From the Canadian patent

Osmium-catalyzed methods of addition to an olefin are discussed. In the method of asymmetric dihydroxylation of the present invention an olefin, a, chiral ligand, an organic solvent an aqueous solution, a base, a ferricyanide salt, and, an osmium-containing compound are combined. The chiral ligand is an alkaloid or, alkaloid derivative linked to an organic substituent of at least 300 daltons molecular, weight through a planar aromatic spacer group. The organic substituent can be another alkaloid or alkaloid derivative. With the described chiral ligands asymmetric dihydroxylation of olefins with high yields and enantiomeric excesses, are achieved.