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Published on: June 21, 2017
Intramolecular arene epoxidation by phosphadioxiranes
Dong Zhang1, Ruomei Gao, Shabana Afzal
1Department of Chemistry and Biochemistry, California State University-Los Angeles, Los Angeles, CA 90032, USA.
Organic Letters
|October 20, 2006
Summary
Singlet oxygen reacts with binaphthyl phosphine derivatives, forming binaphthyl-2-oxide phosphine oxides via intramolecular arene epoxidation. A transient phosphadioxirane intermediate was observed, rearranging to a hydroxylated product with complete stereochemistry retention.
Area of Science:
- Organic Chemistry
- Reaction Mechanisms
- Stereochemistry
Background:
- Phosphine oxides are important in organic synthesis.
- Intramolecular reactions offer unique synthetic pathways.
- Singlet oxygen is a reactive species utilized in oxidation reactions.
Purpose of the Study:
- To investigate the reaction of singlet oxygen with binaphthyl phosphine derivatives.
- To elucidate the mechanism of the observed intramolecular arene epoxidation.
- To characterize the transient intermediates and products.
Main Methods:
- Reaction of 1,1'-binaphthyl di-tert-butyl phosphine with singlet oxygen.
- Low-temperature Nuclear Magnetic Resonance (NMR) spectroscopy for intermediate detection.
- Kinetic analyses to determine reaction pathways.
Main Results:
- Formation of binaphthyl-2-oxide phosphine oxides with complete stereochemistry retention.
- Observation of a transient phosphadioxirane intermediate.
- NIH-rearrangement of the intermediate to a hydroxylated product.
Conclusions:
- A novel intramolecular arene epoxidation reaction has been discovered.
- The reaction proceeds via a phosphadioxirane intermediate.
- The reaction demonstrates high stereochemical control.
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