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Sequential reactions with Grubbs catalyst and AD-mix-alpha/beta using PDMS thimbles
Martin T Mwangi1, Michael D Schulz, Ned B Bowden
1Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
Organic Letters
|December 6, 2008
Summary
Site-isolation of incompatible catalysts within polydimethylsiloxane thimbles enabled novel cascade reactions. This method efficiently facilitated reactions with challenging intermediates, improving synthetic accessibility.
Area of Science:
- Organic Chemistry
- Catalysis
- Materials Science
Background:
- Grubbs catalyst and osmium dihydroxylation catalysts are essential but incompatible.
- Site-isolation strategies are crucial for enabling sequential reactions with incompatible reagents.
Purpose of the Study:
- To develop a method for site-isolating incompatible Grubbs and osmium dihydroxylation catalysts.
- To demonstrate the utility of this method in performing cascade reactions, particularly with volatile or malodorous intermediates.
Main Methods:
- Utilized polydimethylsiloxane (PDMS) thimbles for catalyst site-isolation.
- Encapsulated Grubbs catalyst within PDMS thimbles and placed AD-mix-alpha/beta (containing the osmium catalyst) externally.
- Allowed organic substrates to permeate the PDMS thimble walls for reaction.
Main Results:
- Successfully site-isolated incompatible Grubbs and osmium dihydroxylation catalysts.
- Demonstrated efficient cascade reactions where substrates diffused through PDMS thimbles.
- Developed new cascade reactions involving intermediates with low boiling points or unpleasant odors.
Conclusions:
- Polydimethylsiloxane thimbles provide an effective platform for site-isolation of incompatible catalysts.
- This approach facilitates complex cascade reactions, overcoming challenges associated with intermediate handling and catalyst incompatibility.
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