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Total synthesis of (-)-himgaline
Unmesh Shah1, Samuel Chackalamannil, Ashit K Ganguly
1Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
Journal of the American Chemical Society
|September 28, 2006
Summary
Researchers achieved the first total synthesis of (-)-himgaline and an enantioselective synthesis of (-)-GB 13. These complex molecules were synthesized using novel decarboxylative aza-Michael reactions and cyclization strategies.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
- Natural Product Synthesis
Background:
- (-)-Himgaline and (-)-GB 13 are complex natural products.
- Efficient synthetic routes to these compounds are valuable for chemical research and potential applications.
Purpose of the Study:
- To report the first total synthesis of (-)-himgaline.
- To develop a highly enantioselective synthesis of the related compound (-)-GB 13.
Main Methods:
- Utilized a decarboxylative aza-Michael reaction on a hexacyclic lactone precursor under acidic conditions.
- Employed a basic workup for the synthesis of (-)-GB 13.
- Performed acid-catalyzed cyclization of (-)-GB 13 to oxohimgaline, followed by reduction with sodium triacetoxyborohydride for (-)-himgaline synthesis.
Main Results:
- Successfully synthesized (-)-GB 13 in 80% yield via the decarboxylative aza-Michael reaction.
- Achieved the exclusive formation of (-)-himgaline through cyclization and stereoselective reduction.
Conclusions:
- Established the first total synthesis of (-)-himgaline, demonstrating a novel synthetic pathway.
- Developed a highly enantioselective route to (-)-GB 13, showcasing the utility of the key reaction.
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