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Selective perhydroxylation of squalene: taming the arithmetic demon
G A Crispino1, P T Ho, K B Sharpless
1Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037.
Science (New York, N.Y.)
|January 1, 1993
Summary
Osmium-catalyzed asymmetric dihydroxylation achieves high enantiopurity in synthetic catalysts. This method exhaustively polyhydroxylates squalene, yielding a single stereoisomer with high overall efficiency.
Area of Science:
- Organic Chemistry
- Catalysis
- Stereochemistry
Background:
- Synthetic catalysts rival enzymes in efficiency and enantioselectivity.
- Osmium-catalyzed asymmetric dihydroxylation produces enantiopure 1,2-diols from prochiral olefins.
Purpose of the Study:
- To investigate the exhaustive polyhydroxylation of squalene using osmium-catalyzed asymmetric dihydroxylation.
- To assess the efficiency and stereochemical outcome of this reaction on a polyolefin.
Main Methods:
- Utilized osmium-catalyzed asymmetric dihydroxylation.
- Applied the catalyst to the polyolefin squalene.
- Analyzed the resulting dodecahydroxy derivative for yield and stereoisomeric purity.
Main Results:
- The catalyst exhaustively polyhydroxylates squalene, forming a dodecahydroxy derivative.
- Twelve chemical and stereochemical events occurred in tandem.
- Achieved an average yield of 98% per step, resulting in a 78.9% overall yield for a single stereoisomer.
Conclusions:
- Osmium-catalyzed asymmetric dihydroxylation can achieve exhaustive polyhydroxylation of polyolefins.
- The reaction demonstrates remarkable efficiency and high stereoselectivity, producing a single stereoisomer from a complex substrate.