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.

(+)-Longifolene

Longifolene
Names
IUPAC name (1R,2S,7S,9S)- 3,3,7-trimethyl- 8-methylenetricyclo- [5.4.0.02,9]undecane
Identifiers
CAS Number	(+): 475-20-7 Y (−): 16846-09-6
3D model (JSmol)	(+): Interactive image (−): Interactive image
Beilstein Reference	5731712 2044263 4663756
ChEBI	(+): CHEBI:49282 N (−): CHEBI:49286
ChemSpider	(+): 16739255 N (−): 1013315
ECHA InfoCard	100.006.812
EC Number	(+): 207-491-2
PubChem CID	(+): 1796220 (−): 1201520
UNII	(+): 3YXH7YY8WM
CompTox Dashboard (EPA)	(+): DTXSID9047045
InChI InChI=1S/C15H24/c1-10-11-6-7-12-13(11)14(2,3)8-5-9-15(10,12)4/h11-13H,1,5-9H2,2-4H3/t11-,12-,13+,15-/m1/s1 N Key: PDSNLYSELAIEBU-GUIRCDHDSA-N N
SMILES (+): C[C@]12CCCC([C@@H]3[C@H]1CC[C@@H]3C2=C)(C)C (−): C[C@@]12CCCC([C@H]3[C@@H]1CC[C@H]3C2=C)(C)C
Properties
Chemical formula	C15H24
Molar mass	204.36 g/mol
Density	0.928 g/cm3
Boiling point	254 °C (489 °F; 527 K) (706 mm Hg)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H304, H317, H410
Precautionary statements	P261, P272, P273, P280, P301+P310, P302+P352, P321, P331, P333+P313, P363, P391, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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 biosynthesis of Longifolene

Synthesis and related chemistry

The laboratory characterization and synthesis of longifolene has long attracted attention.^{[4][5][6][7][8][9][10][11]}

Longifolene total synthesis by Corey.svg
Longifolene total synthesis by Corey.svg

It reacts with borane to give the derivative dilongifolylborane, which is a chiral hydroborating agent.^[12]