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The "aqueous" Prins reaction.
Danielle L Aubele1, Christopher A Lee, Paul E Floreancig
1Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Organic Letters
|November 7, 2003
Summary
Prins cyclization reactions are achieved under mild conditions using cyclic acetals and allylsilanes. This Lewis acidic micelle system in water protects intermediates, enabling efficient synthesis of substituted tetrahydropyrans with stereocontrol.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Catalysis
Background:
- Prins cyclization is a key reaction in organic synthesis.
- Protecting electrophilic intermediates from hydrolysis is crucial for reaction efficiency.
- Mild reaction conditions are desirable for broader substrate scope and reduced side reactions.
Purpose of the Study:
- To develop mild and efficient conditions for Prins cyclization reactions.
- To investigate the use of Lewis acidic micelles in aqueous media for organic reactions.
- To synthesize vinyl- and aryl-substituted tetrahydropyrans with high stereocontrol.
Main Methods:
- Utilizing cyclic alpha,beta-unsaturated acetals as oxocarbenium ion progenitors.
- Employing allylsilanes as nucleophiles in the presence of Lewis acidic micelles.
- Conducting Prins cyclization reactions in aqueous colloidal suspensions.
Main Results:
- Prins cyclization reactions proceed efficiently under very mild conditions.
- Lewis acidic micelles effectively protect highly electrophilic intermediates from hydrolysis.
- A variety of vinyl- and aryl-substituted tetrahydropyrans were synthesized with excellent stereocontrol.
Conclusions:
- This study demonstrates a facile and stereoselective method for Prins cyclization in water.
- Lewis acidic micelles offer a protective environment for reactive intermediates in aqueous organic synthesis.
- The developed methodology provides a valuable tool for the preparation of complex tetrahydropyran derivatives.