Ligands for ADH: cinchona alkaloids and moderately sized organic substituents linked through a planar aromatic spacer group
AssigneeMassachusetts Institute of Technology
InventorsJens Hartung, K. Barry Sharpless
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Abstract
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.
Claims9
An osmium-catalyzed method of producing an asymmetrically dihydroxylated olefin, comprising combining olefin, a chiral auxiliary, an organic solvent, an aqueous solution, a base, an osmium-containing catalyst and a ferricyanide salt and maintaining the resulting combination under conditions appropriate for asymmetric dihydroxylation of the olefin to occur, wherein the chiral auxiliary is a cinchona alkaloid covalently linked to an organic substituent of at least 300 daltons molecular weight through a planar aromatic hydrocarbon or nitrogen containing heterocyclic spacer group.
An osmium catalyzed method of producing an asymmetrically dihydroxylated olefin comprising:
- a) combining a chiral auxiliary, an organic solvent, an aqueous solution, a base, a ferricyanide salt and an osmium-containing catalyst in a catalytic quantity, wherein the chiral auxiliary is a cinchona alkaloid covalently linked to an organic substituent of at least 300 daltons molecular weight through a planar aromatic hydrocarbon or nitrogen containing heterocyclic spacer group.
- b) adding the olefin;
- and
- c) maintaining the resulting combination under conditions appropriate for asymmetric dihydroxylation of the olefin to occur.
Dependencies are inferred from the claim text.