Longifolene

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 optical rotation of +42.73°. The other enantiomer (optical rotation −42.73°) is found in small amounts in some primitive plants like fungi and liverworts.

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

Total syntheses

Due to the compact tricyclic structure and lack of Corey^[4][5], McMurray^[6], Johnson^[7], Oppolzer^[8], and Schultz^[9].

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.^[10]

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 1,2-alkyl migration.

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.; J. Org. Chem. 1981, 46, 2988.
4. ^ J. Am. Chem. Soc. 1961, 83, 1251.
5. ^ J. Am. Chem. Soc. 1964, 86, 478.
6. ^ McMurray, J. E.; Isser, S. J. J. Am. Chem. Soc. 1972, 94, 7132.
7. ^ Volkermann, R. A.; Andrews, G. C.; Johnson, W. S. J. Am. Chem. Soc. 1975, 97, 4777-4779.
8. ^ Oppolzer, W.; Godel, T. J. Am. Chem. Soc. 1978, 100, 2584.
9. ^ Schultz, A. G. et al. J. Org. Chem. 1985, 50, 915.
10. ^ Ho, Gregory J. Org. Chem. 2005, 70, 5139 -5143.

• Dev, S. Acc. Chem. Res. 1981, 14, 82-88.