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DOI: 10.1055/s-2008-1077896
Synthesis of (-)-β-Caryophyllene
Contributor(s):Philip Kocienski, Arndt W. SchmidtHarvard University, Cambridge, USA
An Unconventional Approach to the Enantioselective Synthesis of Caryophylloids
J. Am. Chem. Soc. 2008, 130: 2954-2955
Publication History
Publication Date:
23 July 2008 (online)
Key words
caryophyllene - planar chirality - CBS reduction - Grob fragmentation
Significance
The synthesis of β-caryophyllene and coraxenolide A by Larionov and Corey is distinctive because it is a rare example of the use of planar chirality in natural product synthesis. Both enantiomers of (2Z,6E)-6-methylcyclonona-2,6-dienone (H) were prepared and used as chiral precursors for the synthesis of the (-)-β-caryophyllene and coraxeniolide A.
Comment
The absence of stereoselectivity in the reduction of C with NaBH4 was overcome by using the CBS reduction. Planar chiral H was obtained as a single enantiomer that is stable against racemization at room temperature owing to restricted C-C bond rotation in the 9-membered ring. By contrast, cyclononene racemizes in a few minutes at room temperature.