Kaurane

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Kaurane is a parent hydride used in the IUPAC nomenclature of natural products and also, distinctly, in CAS nomenclature. It is a diterpene with a rigid four-ring structure and six chiral centres.

The stereochemistry of the six chiral centres is defined by convention: however, IUPAC and CAS use different conventional stereochemistry, which also leads to a slight difference in numbering between the two systems. IUPAC conventional kaurane has (5S,8S,9S,10S,13S,15R)-stereochemistry, and is drawn with the five-membered ring receding into the plane of the image.[1] CAS conventional kaurane has (5S,8R,9S,10S,13R,15R)-stereochemistry, and is drawn with the five-membered ring protruding from the plane of the image.[2] Carbon-19 (one of the two methyl groups attached to carbon-4) is on the same side of the molecule as the five-membered ring in both systems: hence it is receding into the plane of the image in IUPAC nomenclature and protruding from the plane of the image in CAS nomenclature.

The name ent-kaurane is sometimes used to refer to the CAS conventional kaurane,[3] and so to distinguish it from the IUPAC stereochemistry, in particular by the International Union of Biochemistry and Molecular Biology (IUBMB).[4] It is also possible to explicitly specify the stereochemistry at carbons 8 and 13, giving:

  • (8S,13S)-kaurane (IUPAC conventional)
  • (8R,13R)-kaurane (CAS conventional)

References

  1. Revised Section F: Natural Products and Related Compounds (IUPAC Recommendations 1999). Pure Appl. Chem., 71 (4), 587–643. DOI: 10.1351/pac199971040587.
  2. 57817-89-7 – Kaur-16-en-18-oic acid, 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-, β-D-glucopyranosyl ester, (4α)-. In Common Chemistry; Chemical Abstracts Service, <http://www.commonchemistry.org/ChemicalDetail.aspx?ref=57817-89-7>. (accessed 5 September 2009).
  3. Nagashima, Fumihiro; Tanaka, Hironao; Takaoka, Shigeru; Asakawa, Yoshinori Ent-kaurane-type diterpenoids from the liverwort Jungermannia exsertifolia ssp. cordifolia. Phytochemistry 1996, 41 (4), 1129–41. DOI: 10.1016/0031-9422(95)00755-5. Arriaga-Giner, Francisco Javier; Rumbero, Angel; Wollenweber, Eckhard 16α,19-Diacetoxy-ent-kaurane, a New Natural Diterpene from the Exudate of Ozothamnus scutellifolius (Asteraceae). Z. Naturforsch. C 1999, 54, 602–4. Ding, Lan; Zhang, Zhang-Jing; Liu, Guo-An; Yang, Dong-Juan; Guo, Guo-Cong; Wang, Han; Sun, Kun Three New Cytotoxic ent-Kaurane Diterpenoids from Isodon weisiensis C. Y. Wu. Helv. Chim. Acta 2005, 88 (9), 2502–7. DOI: 10.1002/hlca.200590185. Batista, Ronan; García, Pablo A.; Castro, Maria A.; del Corral, José M. Miguel; San Feliciano, Arturo; de Oliveira, Alaíde B. New oxidized ent-kaurane and ent-norkaurane derivatives from kaurenoic acid. J. Braz. Chem. Soc. 2007, 18 (3), 622–27. DOI: 10.1590/S0103-50532007000300020. Zhao, Yong; Pu, Jian-Xin; Huang, Sheng-Xiong; Ding, Li-Sheng; Wu, Ying-Li; Li, Xian; Yang, Li-Bin; Xiao, Wei-Lie, et al. ent-Kaurane diterpenoids from Isodon pharicus. J. Nat. Prod. 2009, 72 (6), 988–93. PMID 19425589. DOI: 10.1021/np9000366.
  4. EC 1.14.13.78 – ent-kaurene oxidase. In ExPASy Proteomics Server; Swiss Institute of Bioinformatics, <http://www.expasy.org/cgi-bin/nicezyme.pl?1.14.13.78>. (accessed 5 September 2009). EC 1.14.13.79 – ent-kaureneic acid oxidase. In ExPASy Proteomics Server; Swiss Institute of Bioinformatics, <http://www.expasy.org/cgi-bin/nicezyme.pl?1.14.13.79>. (accessed 5 September 2009).

Further reading

External links

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