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Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes
Published on: September 8, 2013
Remarkably mild and efficient intramolecular Friedel-Crafts cyclization catalyzed by In(III)
Ryuji Hayashi1, Gregory R Cook
1Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, ND 58105-5516, USA.
Organic Letters
|March 10, 2007
Summary
Indium(III) salts are highly effective catalysts for intramolecular Friedel-Crafts reactions involving allylic bromides and arenes. These salts exhibit unique halophilic Lewis acid properties, catalyzing reactions even with deactivated aromatic compounds.
Area of Science:
- Organic Chemistry
- Catalysis
- Organometallic Chemistry
Background:
- Friedel-Crafts reactions are fundamental in organic synthesis.
- Developing efficient catalysts for challenging substrates remains an area of active research.
- Lewis acids are commonly employed in Friedel-Crafts alkylations.
Purpose of the Study:
- To investigate the catalytic efficacy of Indium(III) salts in intramolecular Friedel-Crafts reactions.
- To explore the unique properties of Indium(III) as a Lewis acid catalyst.
- To assess the applicability of Indium(III) catalysis to deactivated aromatic systems.
Main Methods:
- Screening of various Indium(III) salts as catalysts.
- Reaction optimization for intramolecular Friedel-Crafts alkylation of allylic bromides and arenes.
- Evaluation of catalyst performance with different arene substrates, including deactivated ones.
Main Results:
- Indium(III) salts demonstrated high catalytic activity for the target reaction.
- Indium(III) salts exhibited unique halophilic Lewis acid behavior.
- Smooth reactions were achieved with deactivated arenes containing chloride, bromide, and fluoride substituents using Indium(III) chloride (InCl3).
Conclusions:
- Indium(III) salts are exceptionally effective and general catalysts for intramolecular Friedel-Crafts reactions.
- The unique halophilic nature of Indium(III) Lewis acids broadens their synthetic utility.
- Indium(III) catalysis provides a viable route for functionalizing deactivated aromatic compounds.
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