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Synthesis of Six-Membered Compounds by Environmentally Friendly Cyclization Using Indirect Electrolysis
Masataka Ihara1, Akira Katsumata, Fumihito Setsu
1Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-77, Japan.
The Journal of Organic Chemistry
|January 26, 1996
Summary
Nickel-catalyzed indirect electroreduction efficiently synthesized six-membered compounds from olefinic bromides. Key alkaloid intermediates for Ipecac and Corynanthe were produced with high yield and stereoselectivity.
Area of Science:
- Organic Chemistry
- Electrochemistry
- Catalysis
Background:
- Olefinic bromides are versatile precursors in organic synthesis.
- Developing efficient and stereoselective methods for their transformation is crucial.
- Nickel-based catalysts offer unique reactivity in reductive processes.
Purpose of the Study:
- To investigate the indirect electroreduction of olefinic bromides using a nickel-cyclam catalyst.
- To explore the synthesis of complex six-membered ring systems.
- To apply the methodology towards the synthesis of alkaloid intermediates.
Main Methods:
- Indirect electroreduction using [Ni(cyclam)](ClO(4))(2) as a catalyst.
- Electrolysis of various olefinic bromides and bromoacetates.
- Stereoselective synthesis of target molecules.
Main Results:
- The catalytic system produced six-membered compounds in low to high yields.
- A key synthetic intermediate (49) for Ipecac and Corynanthe alkaloids was obtained in 88% yield with high stereoselectivity.
- Lactam 66, a precursor to tacamonine, was synthesized in 49% yield.
- Debromination of bromoacetates proceeded in good yields.
Conclusions:
- [Ni(cyclam)](ClO(4))(2) is an effective catalyst for the indirect electroreduction of olefinic bromides.
- The method allows for the stereoselective synthesis of valuable alkaloid precursors.
- Electrochemical reduction offers a viable route for complex molecule synthesis.