Longifolene
Longifolene is a common sesquiterpene. It is an 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] It is a tricyclic chiral molecule. 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.
Occurrence
Terpentine obtained from Pinus longifolia (obsolete name for Pinus roxburghii Sarg.) contains as much as 20% of longifolene.[2]
Longifolene is also one of two most abundant aroma constituents of lapsang souchong tea, because the tea is smoked over pinewood fires.[3]
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.
The laboratory characterization and synthesis of longifolene has long attracted attention.[4][5][6][7][8][9][10][11]
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| Longifolene total synthesis by Corey.svg |
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It reacts with borane to give the derivative dilongifolylborane, which is a chiral hydroborating agent.[12]
References
External links
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- ↑ Template:Ullmann
- ↑ 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)
- ↑ Naffa, P.; Ourisson, G. Bulletin de la Société chimique de France, 1954, 1410.
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- ↑ Ho, Gregory J. Org. Chem. 2005, 70, 5139 -5143.
- ↑ Script error: No such module "Citation/CS1".