New terpene hydrocarbons from the alligatoridae (crocodylia, reptilia)

Article abstract of DOI:10.1021/np020073r

The contents of the paracloacal gland secretions of the alligatorids Alligator mississippiensis, A. sinensis, Paleosuchus palpebrosus, and P. trigonatus were investigated. Novel acyclic hydrocarbon terpenes with a rare trisubstituted 2,4-diene system were identified in the secretions of A. sinensis, P. palpebrosus, and P. trigonatus. The structures of the monoterpene (2E,4E)-3,7-dimethyl-2,4-octadiene (9) and the sesquiterpene (2E,4E,7S)-3,7,11-trimethyl-2,4-dodecadiene (14) were proven by synthesis and gas chromatography on a chiral phase. Several other new terpenes (11, 16, 17, 18, 19, and 20) related to these components also were present in the secretions, as well as the known compounds myrcene (6), (E)-β-farnesene (4), (E)-β-springene (3), squalene (5), cembrene A (1), and 11,12-dihydrocembren-10-one (2).

Full text of DOI:10.1021/np020073r

3
4
J . Nat. Prod. 2003, 66, 34-38
New Ter p en e Hyd r oca r bon s fr om th e Alliga tor id a e (Cr ocod ylia , Rep tilia )
,
†
†
‡
Stefan Schulz,* Karsten Kr u¨ ckert, and Paul J . Weldon
Institut f u¨ r Organische Chemie, Technische Universit a¨ t Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany, and
Conservation and Research Center, Smithsonian Institution, 1500 Remount Road, Front Royal, Virginia 22632
Received February 28, 2002
The contents of the paracloacal gland secretions of the alligatorids Alligator mississippiensis, A. sinensis,
Paleosuchus palpebrosus, and P. trigonatus were investigated. Novel acyclic hydrocarbon terpenes with
a rare trisubstituted 2,4-diene system were identified in the secretions of A. sinensis, P. palpebrosus,
and P. trigonatus. The structures of the monoterpene (2E,4E)-3,7-dimethyl-2,4-octadiene (9) and the
sesquiterpene (2E,4E,7S)-3,7,11-trimethyl-2,4-dodecadiene (14) were proven by synthesis and gas
chromatography on a chiral phase. Several other new terpenes (11, 16, 17, 18, 19, and 20) related to
these components also were present in the secretions, as well as the known compounds myrcene (6),
(
E)-â-farnesene (4), (E)-â-springene (3), squalene (5), cembrene A (1), and 11,12-dihydrocembren-10-one
(2).
The paracloacal glands of crocodilians, a putative source
of pheromones, produce a variety of lipids, including
1
compounds rare or unique among vertebrates. Alligators
and caimans (Alligatoridae), in which the chemistry of skin
gland secretions has been studied most extensively, are
known to contain some unusual terpenoids. In the Chinese
alligator (Alligator sinensis Fauvel), cembrene A (1) and a
related ketone, 11,12-dihydrocembren-10-one (2), have been
2
observed in adult males, but not females. In immature
3
American alligators (A. mississippiensis (Daudin)) and in
adult smooth-fronted caimans (Paleosuchus trigonatus
(
Schneider)), a major glandular component was identified
4
,5
as (E,E)-â-springene (3), a diterpene homologue of (E)-
â-farnesene (4). We report here on our analysis of Alligator
spp. and Paleosuchus spp. and on the identification of
additional terpene hydrocarbons from A. sinensis, P. trigo-
natus, and the dwarf caiman (P. palpebrosus (Cuvier)),
including several new natural products. We also provide
further information on the occurrence among the sexes and
age-classes of some terpenoids previously reported from
alligatorids. Both morphological and molecular data es-
tablish Alligator and Paleosuchus as distantly related
genera of extant Alligatoridae.6 Our results provide a
broader picture of the distribution of hydrocarbon terpe-
noids within this family, and they extend the known
distribution of some compounds among the sexes and age-
classes of these taxa.
3
adult, A. mississippiensis. We confirmed this diterpene in
female P. trigonatus and as a major component of im-
mature A. mississippiensis. We also observed 3 in male,
female, and immature P. palpebrosus. Trace quantities of
this compound were detected in an adult female A. sinensis,
providing the only evidence of it in this species.
Resu lts a n d Discu ssion
Glandular secretions obtained from captive-reared sub-
jects were analyzed by GC-MS. Our results (see Table 1)
confirm the identity of several terpenoids previously re-
ported from the paracloacal glands of Alligator spp. and
Paleosuchus spp. (E)-â-Farnesene (4) was observed in
immature A. mississippiensis, in a female and in immature
P. trigonatus, and in all samples of A. sinensis and P.
palpebrosus; it was not detected in adult A. mississippiensis
or in a male P. trigonatus, which curiously was devoid of
hydrocarbons.
Cembrene A (1) from the paracloacal glands had been
reported in adult male A. sinensis, where it was found to
2
comprise 2% of a dichloromethane extract. We observed
this diterpene in both male A. sinensis and, in lesser
abundance, one pooled sample of females. As with 3 in A.
mississippiensis, compound 1 was most abundant in im-
mature A. sinensis. We also observed it in females of P.
palpebrosus and P. trigonatus and, again in greater abun-
dances, in immatures of both species. 11,12-Dihydrocem-
bren-10-one (2), which like its parent compound also had
â-Springene (3) had been reported as a major component
of male and female P. trigonatus and immature, but not
4
,5
*
To whom correspondence should be addressed. Tel: +49 531 391 7353.
been known only from male A. sinensis, was confirmed in
2
Fax: +49 531 391 5272. E-mail: stefan.schulz@tu-bs.de.
†
both males of this species and, in trace amounts, imma-
tures.
Institut f u¨ r Organische Chemie, Technische Universit a¨ t Braunschweig.
Conservation and Research Center, Smithsonian Institution.
‡
1
0.1021/np020073r CCC: $25.00
© 2003 American Chemical Society and American Society of Pharmacognosy
Published on Web 12/04/2002

Terpene Hydrocarbons from the Alligatoridae
J ournal of Natural Products, 2003, Vol. 66, No. 1 35
Ta ble 1. Distribution of Terpene Hydrocarbons in Paracloacal Gland Secretions of Male (m), Female (f), and Unsexed Immature
Alligator and Paleosuchus spp.a
A. mississippiensis
A. sinensis
P. palpebrosus
P. trigonatus
compound
m (1)
f (1)
i (3)
m (2)
f (3)
i (8)
m (1)
f (1)
i (4)
m (1)
f (1)
i (4)
1
2
3
4
5
6
9
1
1
1
1
1
1
2
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
4.66
27.96
-
0.21
4.01
t
0.04
-
-
t
40.22
1.04
-
-
0.05
-
10.44
0.07
0.31
-
-
-
0.11
0.08
0.07
t
7.15
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.42
-
13.03
0.46
5.00
t
6.13
-
1.23
0.96
3.70
t
-
17.02
t
0.61
0.35
0.09
-
t
t
3.99
2.32
3.51
-
0.07
-
t
-
t
-
-
t
t
0.17
0.06
0.04
t
-
-
-
-
-
-
0.01
t
-
1
4
6
7
8
9
0
-
t
-
-
-
-
0.27
0.11
0.16
0.06
0.11
0.04
-
0.84
0.22
0.27
0.05
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
a
Median content (%) of the total secretion. t: < 0.01%, -: not detected. The number of individuals analyzed is indicated in parentheses.
Sch em e 1. Synthesis of Monoterpene Hydrocarbonsa
F igu r e 1. Mass spectra of compounds A, identified as (2E,4E)-3,7-
dimethyl-2,4-octadiene (9), and B, identified as (2Z,4E)-3,7-dimethyl-
2
,4-octadiene (11).
Squalene (5) is a common vertebrate skin product, but
among alligatorids it had been reported only in Caiman
spp.1 We observed squalene primarily in female and
immature Paleosuchus spp. Myrcene (6), which has not
previously been reported from reptiles, was detected by us
in trace amounts in a male P. palpebrosus and immature
P. trigonatus.
In samples of both P. trigonatus and A. sinensis, two
unknown trace components A (retention index I 1026) and
B (I 1011) were detected in addition. They eluted shortly
after the monoterpene myrcene on an apolar GC phase.
The mass spectra of the two compounds are shown in
Figure 1. The base peak at m/z 95 is formed by a favored
a
(a): KOtBu.
not be obtained in pure form. Nevertheless, the identical
retention time and MS data proved our structural assign-
ment of B to be correct. Neither compound has previously
been reported from a natural source, but they have been
8
-10
prepared synthetically in mixtures or by elaborate routes.
In the secretions of P. palpebrosus and A. sinensis two
sesquiterpenes C (I 1469) and D (I 1448) occurred in minor
amounts (up to 0.5% of the samples); they showed mass
spectra similar to that of 9 (see Figure 2). The ions at m/z
71 and 123 point to a saturated isopentyl-end of the
molecule. From these data and the strong diagnostic ion
at m/z 95, 3,7,11-trimethyl-2,4-dodecadiene was proposed
as the structure of the natural compounds. The synthesis
shown in Scheme 2 proved our assignment. (S)-Citronellol
(12) was converted by hydrogenation and bromination into
the respective bromide. After conversion into the alkyltri-
phenylphosphonium bromide 13, Wittig reaction with E-8
furnished the desired compound, (2E,4E,7S)-3,7,11-tri-
methyl-2,4-dodecadiene 14. The formation of its minor
(2E,4Z)-diastereomer 15 can be suppressed when Schlo-
sser-type reaction conditions are used,11 changing the 14/
15 ratio from 2:1 to 94:6. Racemic 14 was synthesized in
an identical procedure from rac-12, thus enabling deter-
mination of the absolute configuration of the natural
compound. Chiral gas chromatography using a cyclodextrin
phase revealed that the natural 14 obtained from A.
sinensis has an S-configuration and is enantiomerically
pure (see Figure S1, Supporting Information). The minor
natural compound D was tentatively identified for similar
reasons as explained above in the identification of B as
(2Z,4E)-3,7,11-trimethyl-2,4-dodecadiene, 16.
3 7
loss of a fragment of 43 amu, most probably C H . The
spectra were reminiscent of hydrocarbon monoterpenes.
Therefore, 3,7-dimethyl-2,4-octadiene was proposed as their
structure because allylic bond cleavage can be expected to
give rise to a prominent ion at m/z 95. For verification of
the structures the compounds were synthesized as shown
in Scheme 1. Reaction of the ylide derived from 3-methyl-
butyltriphenylphosphonimun bromide (7) and tiglic alde-
hyde (E-8) furnished a mixture of (2E,4E)-3,7-dimethyl-
2
,4-octadiene (9) and its (2E,4Z)-isomer (10). Compound 9
showed MS and GC data identical with the later-eluting
natural compound A, thus confirming the proposed struc-
ture and establishing its E,E-configuration. The earlier
eluting compound B showed slightly different GC and MS
data compared to 10 (I 978). Because it seems unlikely that
the natural compounds show a different configuration in
both double bonds, we propose (2Z,4E)-3,7-dimethyl-2,4-
octadiene (11) as the structure of compound B. This was
verified by its synthesis using the very unstable aldehyde
(
Z)-8 as starting material. Because of the many byproducts
7
formed during preparation and reaction of (Z)-8, 11 could

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6
J ournal of Natural Products, 2003, Vol. 66, No. 1
Schulz et al.
F igu r e 2. Mass spectra of compounds C, identified as (2E,4E)-3,7,-
1-trimethyl-2,4-dodecadiene (14), and D, tentatively identified as
2Z,4E)-3,7,11-trimethyl-2,4-dodecadiene (16).
F igu r e 3. Mass spectra of compounds E (A), identified as (2E,4E)-
3,7,11-trimethyl-2,4,10-dodecatriene (caparratriene, 17), and F (B),
tentatively identified as (2Z,4E)-3,7,11-trimethyl-2,4,10-dodecatriene
1
(
(18).
Sch em e 2. Synthesis of Sesquiterpene Hydrocarbonsa
same route as 14, except for using the phosphonium salt
of citronellyl bromide instead of 13 in the Wittig-Schlosser
reaction. The GC retention index (I) of the later-eluting
component E was determined to be 1506 on a BPX-5 phase.
The minor component F has a value I of 1485. The
difference ∆I of 21 units between both isomers is the same
as between the related compounds 14 and 16. From these
data the structure of (2Z,4E)-3,7,11-trimethyl-2,4,10-dodec-
atriene (18) was assigned to F . Interestingly, synthetic
studies revealed that the absolute configuration of 17 in
O. caparrapi is R.1
4,15
The caparratriene from the alliga-
torids we examined exhibits the opposite S-configuration,
which was proven by chiral gas chromatography.
a
(a) H
2
, Pd/C; (b) PPh
3
Br
2
, CH
2
Cl
2
; (c) PPh
3
, ∆; (d) PhLi, E-8.
Separation of the glandular secretion of A. sinensis by
column chromatography on silica furnished a fraction
containing the compounds 14, 16, 17, 18, and two later-
eluting components, G and H, with a molecular mass of
2
74 (Figures 4 and 5). Their mass spectra were very
similar, especially in the lower mass region, to those of the
caparratrienes.13 The mass shift of 68 amu together with
a diagnostic ion at m/z 205 (M - 69) pointed to an
additional isopentenyl group in the molecules. The occur-
rence of an ion at M - 29, which is surprising, can be seen
in all spectra of the compounds reported here. From these
results we tentatively conclude that these compounds are
(2E,4E,10E)- and (2Z,4E,10E)-3,7,11,15-tetramethyl-2,4,-
1
0,14-hexadecatetraene (19 and 20), analogous with the
other diene terpenes reported here.
Interestingly, great variation in the presence of hydro-
carbons was observed among the alligatorids we examined.
In A. sinensis, compounds 9, 11, 14, and 16-20 were
observed only in samples of adults from St. Augustine,
Florida, while none was observed in other specimens.
Compounds 14 and 16-18 also were observed in adult P.
palpebrosus from Florida. Variation in glandular chemistry
may be due to differences in diet, holding facilities (indoor
versus outdoor), or other aspects of their captive environ-
ments. In any case, this is the first report to suggest
differences in crocodilian skin gland products at different
captive facilities.
The conjugated 2,4-diene system has recently been
identified in the related sesquiterpene caparratriene (17),
which has been isolated from the tree Ocotea caparrapi
from the Colombian rainforest.12 The very similar mass
spectra of two unknown components E (I 1507) and F
(
I 1486) (Figure 3) in the secretion of P. palpebrosus and
1
3
A. sinensis matched the published one of 17. These
compounds thus seem to be diastereomers. The identity of
E and 17 was proven by synthesis. Thus, (2E,4E)-3,7,11-
trimethyl-2,4,10-dodecatriene (17) was synthesized by the

Terpene Hydrocarbons from the Alligatoridae
J ournal of Natural Products, 2003, Vol. 66, No. 1 37
F igu r e 4. Gas chromatogram of a fraction obtained from glandular secretion of Alligator sinensis by column chromatography on silica.
Sa m p le Collection . Paracloacal gland secretions were
obtained during J anuary 1999 at the St. Augustine Alligator
Farm (SA), Florida, where subjects were kept year-round in
outdoor enclosures and fed nutria (Myocastor coypus); at the
Bronx Zoo (BZ), New York, where they were kept indoors and
fed mice and fish; and at the National Aquarium in Baltimore
(NA), Maryland, where they were kept indoors and fed
earthworms, crickets, fish, and mice. Secretions from A.
sinensis were obtained from six adults, each at least 1.2 m
(total length), and eight (unsexed) immatures, ranging from
0
.5 to 0.9 m. Samples from one adult male, one adult female,
and four immatures (0.5 m each) were obtained at SA. Samples
from one adult male, two adult females, and four immatures
(
0.8-0.9 m) were obtained at BZ. Secretions from A. missis-
sippiensis were obtained from one adult male, one adult female
each 1.5 m), and three immatures (0.8 m) at SA. Secretions
(
from P. palpebrosus were obtained from one adult male (1.1
m) and one adult female (1.2 m) at SA and four immatures
(
0.2-0.6 m) at BZ. Secretions from P. trigonatus were obtained
from one adult male (1.5 m) and one adult female (1.4 m) from
SA and from four immatures (0.5 m each) from NA.
Secretions of adults and immatures were collected by
manually placing pressure on the glands, as described by
3
Ibrahim et al. Secretion samples were placed into glass vials
with pentane, and the vials were placed on dry ice. Secretion
samples from immatures of each species from each facility
were pooled in one vial; samples from individual adults were
kept separate, except those from two adult female A. sinensis
from BZ, which were pooled.
Separation of the secretion of A. sinensis was performed by
column chromatography on silica (230-400 mesh, 9 × 40 mm)
with pentane as eluent.
F igu r e 5. Mass spectra of compounds G and H, tentatively identified
as 3,7,11,15-tetramethyl-2,4,10,14-hexadecatetraenes 19 and 20.
We have identified new open-chain terpenes in the
paracloacal glandular secretions of several alligatorids.
They all contain an unusual trisubstituted conjugated
diene system, which has so far only rarely been observed
in terpenes from other natural sources.
Id en tifica tion of Com p ou n d s 1-6. The known com-
pounds were identified by comparison of mass spectra and
retention times with those of standard samples.
Exp er im en ta l Section
Gen er a l P r oced u r e for Wittig Rea ction of Ald eh yd es
(E- a n d Z-8). A solution of 2.6 mmol of triphenylphosphonium
salt 7 or 13 in a 2:1 mixture of THF and 1,2-dimethoxyethane
was cooled to -70 °C, and slowly 2.9 mL of a 1 M solution of
lithium hexamethyldisilazide in hexane was added. At this
temperature 3.48 mmol of freshly distilled 8 was slowly added
and stirred for 18 h after removal of the cooling bath. Water
was added and the reaction mixture extracted five times with
diethyl ether. The combined organic phases were washed with
1
Gen er a l Exp er im en ta l P r oced u r es. The H (400 MHz)
and 13C (100 MHz) NMR spectra were recorded on a Bruker
DRX-400 NMR spectrometer. Chemical shifts are reported in
ppm (δ) and referenced to TMS. Assignments of carbons were
made by DEPT and HSQC experiments, while diastereomer
assignments were corroborated by analysis of coupling con-
stants and NOESY experiments. GC-MS analyses were
performed on a Hewlett-Packard 6890 gas chromatograph
coupled to a Hewlett-Packard 5973 detector, using a BPX-5
capillary column (0.22 mm × 25 m, 0.25 µm film) in splitless
injection mode. Separations of enantiomers were performed
with the same system, equipped with a heptakis(2,6-dimethyl-
4
water and brine and dried with MgSO . The solvent was
removed, pentane added, and the mixture filtered, thus
removing triphenylphosphine oxide. The solvent was removed
under reduced pressure and the crude product subjected to
column chromatography on silica. The resulting 2,4-dienes
showed a high tendency to isomerize to the respective 3,5-
dienes during chromatography. The products were obtained
in a 3:1 (2E,4E)/(2E,4Z)-mixture. Attempts to separate the
3
-O-pentyl)-â-cyclodextrin (50% in OV1701) phase16 operated
isothermal at 70 °C. Helium was used as the carrier gas in all
cases.

3
8
J ournal of Natural Products, 2003, Vol. 66, No. 1
Schulz et al.
isomers by argentation chromatography resulted in extensive
isomerization, thus making the isolation of pure compounds
impossible. NMR data were obtained from mixed samples.
Higher (2E,4E)/(2E,4Z)-ratios up to 96:4 were obtained using
H-9, H-10), 0.84-0.88 (9H, d, J ) 6.8 Hz, H-12, H-12′, 7-CH
3
);
1
3
C NMR (CDCl
3
, 100 MHz) δ 134.7 (s, C-3), 133.4 (d, C-4),
128.6 (d, C-5), 124.4 (d, C-2), 39.2 (t, C-10), 36.9 (t, C-8), 35.8
(t, C-6), 33.2 (d, C-7), 27.9 (d, C-11), 24.8 (t, C-9), 22.7 (q, C-12,
1
1
Schlosser-type reaction conditions.
2E,4E)-3,7-Dim eth ylocta -2,4-d ien e (9): colorless oil; H
NMR (CDCl , 400 MHz) δ 6.04 (1H, d, H-4), 5.54 (1H, dt,
4,5 ) 15.5 Hz, J 5,6 ) 7.5 Hz, H-5), 5.44 (1H, q, H-2), 1.97 (2H,
bt, H-6), 1.73 (3H, bs, 3-CH ), 1.70 (d, 3H, J 1,2 ) 7.6 Hz, H-1),
3 3 3
11-CH ), 19.6 (q, 7-CH ), 16.5 (q, 3-CH ), 13.6 (q, C-1); EIMS
1
+
(
m/z 208 [M] (29), 123 (16), 107 (15), 95 (100), 82 (98), 71 (25),
67 (45), 57 (33), 43 (37), 41 (37); HREIMS m/z 208.2184 (calcd
3
J
for C15
H28, 208.2192).
3
(
2E,4E)-3,7,11-Tr im eth yl-2,4,10-d od eca tr ien e (17): col-
1
.63 (1H, m, H-7), 0.89 (6H, d, J ) 7.6 Hz, H-8 and H-8′); 13
C
1
13
orless oil; the H NMR and C NMR data are identical to those
reported by Palomino and Maldonado. The MS data are
identical to those reported by J oulain and K o¨ nig.
NMR (CDCl
3
, 100 MHz) δ 135.7 (d, C-4), 134.5 (s, C-3), 126.0
12
(
d, C-5), 124.3 (d, C-2), 42.3 (t, C-6), 28.8 (d, C-7), 22.3 (q, C-8,
C-8′), 13.7 (q, C-1), 12.1 (q, 3-CH ); EIMS, see Figure 1;
HREIMS m/z 138.1399 (calcd for C10 18, 138.1409).
2E,4Z)-3,7-Dim eth ylocta -2,4-d ien e (10): colorless oil; H
13
3
H
Ack n ow led gm en t. We thank J . Brueggen, J . Darlington,
S. Huber, D. Kledzik, W. Puckett, and T. Rexroad (St.
Augustine Alligator Farm, FL); J . Behler, W. Holmstrom, and
S. Lee (Bronx Zoo, NY); and W. Brown and J . Cover (National
Aquarium in Baltimore, MD) for access to crocodilians in their
care; and S. Yildizhan for technical assistance. Financial
support by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industrie is gratefully acknowledged.
1
(
NMR (CDCl , 400 MHz) δ 5.83 (1H, d, H-4), 5.41 (1H, q, H-2),
3
5
.27 (1H, dt, J 4,5 ) 7.2 Hz, J 5,6 ) 11.6 Hz, H-5), 2.13 (2H, bt,
H-6), 1.77 (3H, bs, 3-CH ), 1.62 (1H, m, H-7), 1.60 (d, 3H,
J
3
1,2 ) 7.6 Hz, H-1), 0.89 (6H, d, J ) 6.6 Hz, H-8 and H-8′); 13
C
NMR (CDCl , 100 MHz) δ 133.7 (s, C-3), 133.3 (d, C-4), 128.3
3
(d, C-5), 124.5 (d, C-2), 37.7 (t,C-6), 29.2 (d, C-7), 22.4 (q, C-8,
+
C-8′), 16.4 (q, 3-CH
23 (18), 109 (63), 95 (93), 82 (36), 67 (100), 55 (31), 41 (32);
HREIMS m/z 138.1393 (calcd for C10 18, 138.1409).
2E,4E)-3,7,11-Tr im eth yld od eca -2,4-d ien e (14): colorless
oil; IR (gas) νmax 2957, 2931, 1711, 1650, 1460, 1380, 1226,
3
), 13.5 (q, C-1); EIMS m/z 138 [M] (46),
1
Su p p or tin g In for m a tion Ava ila ble: Gas chromatographic sepa-
rations of enantiomers R- and S-14. This material is available free of
charge via the Internet at http://pubs.acs.org.
H
(
1
1
160, 960, 792 cm-1; H NMR (CDCl
d, H-4), 5.54 (1H, dt, J 4,5 ) 15.5 Hz, J 5,6 ) 7.5 Hz, H-5), 5.44
1H, q, H-2), 2.19-2.27 (1H, m, H-6), 2.04-2.10 (1H, m, H-6),
.73 (3H, bs, 3-CH ), 1.71 (3H, d, J 1,2 ) 7.6 Hz, H-1), 1.48 (1H,
sept, H-11), 1.45-1.53 (1H, m, H-7), 1.02-1.35 (6H, m, H-8,
H-9, H-10), 0.85-0.88 (9H, d, J ) 6.6 Hz, H-12, H-12′, 7-CH );
, 100 MHz) δ 135.7 (d, C-4), 134.3 (s, C-3),
25.9 (d, C-5), 124.3 (d, C-2), 39.3 (t, C-10), 37.0 (t, C-8), 35.9
t, C-6), 33.5 (d, C-7), 28.0 (d, C-11), 24.9 (t, C-9), 22.6 (q, C-12,
C-12′), 19.7 (q, 7-CH ), 13.7 (q, C-1), 12.1 (q, 3-CH ); EIMS,
see Figure 2; HREIMS m/z 208.2187 (calcd for C15 28, 208.2192).
3
, 400 MHz) δ 6.04 (1H,
Refer en ces a n d Notes
(
1
(1) Weldon, P. J .; Wheeler, J . W. In Crocodilian Biology and Evolution;
Grigg, G. C., Seebacher, F., Franklin, C. E., Eds.; Surrey Beatty &
Sons: Chipping Norton, 2000; pp 286-296.
3
(
2) Mattern, D. L.; Scott, W. D.; McDaniel, C. A.; Weldon, P. J .; Graves,
3
D. E. J . Nat. Prod. 1997, 60, 828-831.
1
3
C NMR (CDCl
3
(3) Ibrahim, S. A.; Avery, J . W.; Weldon, P. J .; Wheeler, J . W. Z.
Naturforsch. 1998, 53c, 201-209.
1
(
(4) Shafagati, A.; Weldon, P. J .; Wheeler, J . W. Biochem. Syst. Ecol. 1989,
1
7, 431-435.
3
3
(5) Avery, J . W.; Shafagati, A.; Turner, A.; Wheeler, J . W.; Weldon, P. J .
H
Biochem. Syst. Ecol. 1993, 21, 533-534.
(
6) Brochu, C. A.; Densmore, L. D., III. In Crocodilian Biology and
Evolution; Grigg, G. C., Seebacher, F., Franklin, C. E., Eds.; Surrey
Beatty & Sons: Chipping Norton, 2000; pp 3-8.
The compound rearranged during standing or column chro-
matography to 3,7,11-trimethyldodeca-3,5-diene: IR (gas) νmax
1
2
960, 2934, 1650, 1461, 1380, 1041, 956, 843, 723 cm-1; H
(7) Niestroj, M.; Neumann, W. P. Chem. Ber. 1996, 129, 45-61.
(8) Caporusso, A. M.; Giacomelli, G.; Lardicci, L. J . Chem. Soc., Perkin
Trans. 1 1981, 1900-1908.
NMR (CDCl
m, H-6), 5.27 (1H, m, J 4,5 ) 11.8 Hz, J 5,6 ) 15.5 Hz, H-5), 2.02-
.13 (3H, m, H-6, H-2), 1.76 (3H, s, H-13), 1.48-1.58 (1H, m,
H-11), 1.05-1.38 (6H, m, H-8, H-9, H-10), 0.94 (3H, t, J 1,2
3
, 400 MHz) δ 5.80 (1H, d, H-4), 5.38-5.46 (1H,
(
9) Banthorpe, D. V.; Fitton, H.; Lewis, J . J . Chem. Soc., Perkin Trans.
2
1
1973, 2051-2057.
)
(10) Fujita, Y.; Fujita, S.; Okura, H. Osaka Kogyo Gijutsu Shikensho Kiho
1974, 25, 211-215.
1
3
7
(
.4 Hz, H-1), 0.84-0.92 (9H, d, H-12, H-12′, 7-CH
3
); C NMR
(
(
(
(
11) Schlosser, M.; Tuong, H. B.; Schaub, B. Tetrahderon Lett. 1985, 26,
CDCl , 100 MHz) δ 142.9 (s) 133.4 (d), 128.8 (d), 128.3 (d),
3
3
11-314.
4
2
1
7
0.5 (t), 36.6 (t), 34.0 (d), 33.7 (d), 28.0 (d), 26.9 (t), 22.7 (q),
2.6 (q), 19.6 (q), 16.5 (q), 12.2 (q); EIMS m/z 208 [M]+ (32),
93 (1), 179 (6), 123 (100), 109 (14), 95 (83), 82 (52), 81 (51),
1 (17), 67 (54), 57 (29), 55 (29), 43 (29), 41 (33).
12) Palomino, E.; Maldonado, C.; Kempff, M. B.; Ksebati, M. B. J . Nat.
Prod. 1996, 59, 77-79.
13) J oulain, D.; K o¨ nig, W. A. The Atlas of Spectral Data of Sesquiterpene
Hydrocarbons; E.-B. Verlag: Hamburg, 1998.
14) Li, J .; Liu, Z.; Lan, J .; Li, Y. J . Chin. Chem. Soc. (Taipei) 1999, 46,
259-262.
(
2E,4Z)-3,7,11-Tr im eth yld od eca -2,4-d ien e (15): colorless
1
oil; H NMR (CDCl
q, H-2), 5.27 (1H, dt, H-5, J 4,5 ) 11.9 Hz, J 5,6 ) 7.3 Hz), 2.06-
.11 (1H, m, H-6), 1.76 (3H, s, 3-CH
3
, 400 MHz) δ 5.84 (1H, d, H-4), 5.43 (1H,
(15) Li, J .; Liu, Z.; Lan, J .; Li, Y. Chem. Lett. 1997, 229-230.
(16) K o¨ nig, W. A.; Gehrcke, B.; Icheln, D.; Evers, P.; D o¨ nnecke, J .; Wang,
W. J . High Resol. Chromatogr. 1992, 15, 367-372.
2
7
3
), 1.69 (3H, d, H-1, J 1,2 )
.1 Hz), 1.42-1.52 (2H, m, H-7, H-11), 1.04-1.34 (6H, m, H-8,
NP020073R