Germacrene C → delta-Elemene

HRID 1251302Notes

Reaction equation

HRID 1251302 reaction equation
[CH3:1][C:2]1=[CH:3][CH2:4][CH2:5][C:6]([CH3:15])=[CH:7][CH:8]=[C:9]([CH:12]([CH3:14])[CH3:13])[CH2:10][CH2:11]1>CCCCC>[CH3:14][CH:12]([C:9]1[CH2:8][CH2:7][C:6]([CH:5]=[CH2:4])([CH3:15])[CH:11]([C:2]([CH3:1])=[CH2:3])[CH:10]=1)[CH3:13]

Participants

3

Reactant 1

HCID 25244915Germacrene C

Product 1

HCID 89316delta-Elemene

Reagents, catalysts & solvents 1

HCID 8003PentaneSolvent

Conditions

Temperature
35 °C

Procedure

Preliminary studies, in which leaf extracts were compared to steam distillates by standard GC-MS methods (hot injector) and by cool on-column injection, revealed that the target metabolite, germacrene C (FIG. 1), was prone to thermal rearrangement to a compound with shorter GC retention time but nearly identical mass spectrum. This compound was absent in the pentane leaf extract when analyzed by cool (35° C.) on-column injection, but was present when the same pentane extract was injected onto a hot (230° C.) injector (FIG. 2). Comparison of this compound with authentic δ-elemene (FIG. 1) from black pepper oleoresin yielded an identical retention time and mass spectrum. Heating purified germacrene C in a sealed container to 130° C. for 1 h resulted in complete conversion to δ-elemene which was confirmed by GC-MS. Conversion of germacrene C to δ-elemene has been reported previously (Morikawa and Hirose, Tetrahedron Lett. 22:1799-1801, 1969). The sesquiterpene fraction of ‘VFNT Cherry’ leaves (3.2% of total volatile olefins) contained germacrene C (66%), germacrene A (7%), guaia-6,9-diene (7%), germacrene B (6%), β-caryophyllene (6%), germacrene D (4%), α-humulene (4%), and β-elemene (1%). This is the first report of azulane (guaia-6,9-diene) and germacrane skeletal types in tomatoes. By contrast, the sesquiterpene fraction of leaves from the commercial tomato variety ‘Better Boy’ (3.3% of total volatile olefins) contained mostly β-caryophyllene (71%), germacrene C (15%), and α-humulene (9%). The sesquiterpene composition of ‘Better Boy’ agrees with previous reports on the content of L. esculentum leaf oil (Buttery et al., J. Agric. Food Chem. 35:1039-1042, 1987; and Lundgren et al., Nord. J. Bot. 5:315-320, 1985), except that no δ-elemene was found by on-column injection; germacrene C has not been previously observed in Lycopersicon.

Workup

  1. temperatureby cool on-column injection
  2. extractionextract when
  3. extractionextract
  4. customwas injected onto a hot (230° C.) injector (FIG. 2)

Sources & evidence

ORD record
ord-79723440e960487588faee0c4537f897
Source dataset
uspto-grants-2002_01
Patent number
US06342380B1

Reaction notes

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