Longifolene

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(+)-Longifolene
IUPAC name

(1R,2S,7S,9S)- 3,3,7-trimethyl- 8-methylenetricyclo- [5.4.0.02,9]undecane

Identifiers
CAS number 475-20-7 YesY
ChemSpider 1406720 YesY
Jmol-3D images {{#if:C1(=C)[C@]2(CCCC([C@@H]3[C@@H]1CC[C@@H]23)(C)C)C|Image 1
Properties
Molecular formula C15H24
Molar mass 204.36 g/mol
Density 0.928 g/cm3
Boiling point 254 °C (706 mm Hg)
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Longifolene is the common (or trivial) chemical name of a naturally occurring, oily liquid hydrocarbon found primarily in the high-boiling fraction of certain pine resins. The name is derived from that of a pine species from which the compound was isolated,[1] Pinus longifolia (obsolete name for Pinus roxburghii Sarg.)[2]

Chemically, longifolene is a tricyclic sesquiterpene. This molecule is chiral, and the enantiomer commonly found in pines and other higher plants exhibits a positive optical rotation of +42.73°. The other enantiomer (optical rotation −42.73°) is found in small amounts in certain fungi and liverworts.

Longifolene is used in organic synthesis for the preparation of dilongifolylborane,[3] a chiral hydroborating agent.

Longifolene is also one of two most abundant aroma constituents of lapsang souchong tea, because the tea is smoked over pine fires.[4]

Total syntheses

Due to the compact tricyclic structure and lack of functional groups, Longifolene is an attractive target for research groups highlighting new synthetic methodologies. Notable syntheses are by Corey,[5][6] McMurray,[7] Johnson,[8] Oppolzer,[9] and Schultz.[10]

Longifolene total synthesis by Corey.svg

The Johnson biosynthesis has since been validated as feasible using modern quantum mechanical computational methods. The subsequent cationic cascade mechanism has been shown to go through a non-classical cation intermediate.[11]

Biosynthesis

The biosynthesis of longifolene begins with farnesyl diphosphate (1) (also called farnesyl pyrophosphate) by means of a cationic polycyclization cascade. Loss of the pyrophosphate group and cyclization by the distal alkene gives intermediate 3, which by means of a 1,3-hydride shift gives intermediate 4. After two additional cyclizations, intermediate 6 produces longifolene by a 1,2-alkyl migration.

Use

The borane derivative dilongifolylborane is used in organic synthesis as a chiral hydroborating agent.[12]

External links

References

  1. ↑ Naffa, P.; Ourisson, G. Bulletin de la Société chimique de France, 1954, 1410.
  2. ↑ Simonsen, J. L. J. Chem. Soc. 1920, 117, 570.
  3. ↑ Jadhav, P. K.; Brown, H. C. J. Org. Chem. 1981, 46, 2988.
  4. ↑ Shan-Shan Yao； Wen-Fei Guo； YI Lu； Yuan-Xun Jiang, "Flavor Characteristics of Lapsang Souchong and Smoked Lapsang Souchong,a Special Chinese Black Tea with Pine Smoking Process", Journal of Agricultural and Food Chemistry, Vol. 53, No.22, (2005)
  5. ↑ Corey, E. J. et al. J. Am. Chem. Soc. 1961, 83, 1251.
  6. ↑ Corey, E. J. et al. J. Am. Chem. Soc. 1964, 86, 478.
  7. ↑ McMurray, J. E.; Isser, S. J. J. Am. Chem. Soc. 1972, 94, 7132.
  8. ↑ Volkermann, R. A.; Andrews, G. C.; Johnson, W. S. J. Am. Chem. Soc. 1975, 97, 4777-4779.
  9. ↑ Oppolzer, W.; Godel, T. J. Am. Chem. Soc. 1978, 100, 2583.
  10. ↑ Schultz, A. G. et al. J. Org. Chem. 1985, 50, 915.
  11. ↑ Ho, Gregory J. Org. Chem. 2005, 70, 5139 -5143.
  12. ↑ Dev, Sukh (1981). "Aspects of longifolene chemistry. An example of another facet of natural products chemistry". Accounts of Chemical Research 14 (3): 82–88. 


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