Electrocatalytic asymmetric dihydroxylation of olefinic compounds
AssigneeSepracor Inc.
InventorsYun Gao, Charles M. Zepp
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Abstract
A process is disclosed in which optically active glycols are produced through an electrolytic asymmetric dihydroxylation (ADH) reaction involving olefins as substrates. The ADH reaction is mediated by a catalytically active amount of osmium tetroxide or osmium-containing precursor in a protic medium in the presence of chiral ligand. Any lower valent osmium species produced in the course of the ADH reaction is regenerated electrolytically either directly in the absence of a secondary oxidant or indirectly in the presence of a secondary oxidant that itself undergoes electrolytic regeneration.
Claims35
A method of preparing optically active glycols comprising:
- (a) conducting an asymmetric dihydroxylation of an olefin in a medium comprising water and an oxidation resistant organic solvent in the presence of a catalytically active amount of a complex comprising osmium tetroxide and a chiral oxidation resistant tertiary amine ligand;
- (b) employing an effective amount of a secondary oxidant to generate osmium tetroxide, which reparticipates in said asymmetric dihydroxylation, by chemical oxidation from lower valent osmium species;
- and
- (c) electrolytically regenerating secondary oxidant, which reparticipates in said chemical oxidation, from spent secondary oxidant species,
- under conditions effective to provide optically active glycols in amounts which exceed the combined amount in moles of osmium tetroxide and secondary oxidant present initially.
A method of preparing optically active glycols comprising:
- (a) contacting an olefin with an effective amount of osmium tetroxide or an osmium-containing precursor in a medium comprising water and an oxidation resistant organic solvent in the presence of an effective amount of a secondary oxidant and an effective amount of a chiral oxidation resistant tertiary amine ligand;
- (b) producing catalytic amounts of osmium tetroxide by chemical oxidation of said osmium-containing precursor or lower valent osmium species derived from a reduction of said osmium tetroxide;
- (c) forming a catalytically active chiral complex of said ligand with osmium tetroxide;
- (d) passing an amount of current through said medium effective to regenerate effective amounts of said secondary oxidant from spent secondary oxidant produced from said chemical oxidation,
- under conditions effective to provide optically active glycols in amounts which exceed the combined amount in moles of osmium tetroxide or osmium-containing precursor and secondary oxidant present initially.
Dependencies are inferred from the claim text.