A general method for the synthesis of E and/or Z oligoisoprenoids based on Pd-catalyzed homoallyl-alkenyl and homopropargyl-alkenyl cross coupling and Zr-catalyzed carboalumination
✍ Scribed by Ei-ichi Negishi; Show-Yee Liou; Caiding Xu; Shouquan Huo
- Book ID
- 104323692
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 59 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0277-5387
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✦ Synopsis
A truly general, versatile, and highly regioselective and stereoselective methodology for the synthesis of terpenoids containing 1,5-diene units of E and/or Z geometry critically involves (a) Pd-catalyzed homoallyl-alkenyl and homopropargyl-alkenyl coupling and (b) Zrcatalyzed carboalumination of alkynes. In each introduction of an E or Z trisubstituted C 5 alkene unit, the yield is excellent, and the regioselectivity and stereoselectivity level is )98%. As such, this appears to represent the first general synthetic method accommodating Z alkene units in )95% regioselectivity and stereoselectivity. Its application to some representative terpenoids of both natural and unnatural geometries is discussed.