Identification, syntheses, and characterization of the geometric isomers of 9,11-hexadecadienal from female pheromone glands of the sugar cane borer Diatraea saccharalis

Article abstract of DOI:10.1021/np010551i

Chemical analysis of the pheromone glands of the sugar cane borer Diatraea saccharalis has shown the presence of the four geometric isomers of 9,11-hexadecadienal (1-4), in addition to hexadecanal and (Z)-hexadec-11-enal. We here report the syntheses and characterization of compounds 1-4, One starting material, 9-decen-1-ol, has been used to obtain all of them via divergent synthetic routes.

Full text of DOI:10.1021/np010551i

J . Nat. Prod. 2002, 65, 909-915
909
Id en tifica tion , Syn th eses, a n d Ch a r a cter iza tion of th e Geom etr ic Isom er s of
9,11-Hexa d eca d ien a l fr om F em a le P h er om on e Gla n d s of th e Su ga r Ca n e Bor er
Dia tr a ea sa cch a r a lis
Ellen M. Santangelo,† Myrian Coracini,‡ Peter Witzgall,‡ Arlene G. Correa,§ and C. Rikard Unelius,*,†,
Department of Chemistry, Organic Chemistry, The Royal Institute of Technology, SE-10044 Stockholm, Sweden,
Department of Plant Protection Sciences, Swedish University of Agricultural Sciences, SE-23053 Alnarp, Sweden, and
Departamento de Quı´mica, Universidade Federal de Sa˜o Carlos, 13565-905 Sa˜o Carlos SP, Brazil
Received November 2, 2001
Chemical analysis of the pheromone glands of the sugar cane borer Diatraea saccharalis has shown the
presence of the four geometric isomers of 9,11-hexadecadienal (1-4), in addition to hexadecanal and
(Z)-hexadec-11-enal. We here report the syntheses and characterization of compounds 1-4. One starting
material, 9-decen-1-ol, has been used to obtain all of them via divergent synthetic routes.
Most sex pheromones identified in lepidopteran insects
are unsaturated straight-chain aliphatic alcohols, acetates,
or aldehydes.1 The reproductive isolation of the various
species is promoted by species-specific mating signals, given
by groups of structurally related compounds,2 such as
geometric and positional isomers of acetates, alcohols, or
aldehydes.
The main sex pheromone component in a Diatraea
species is usually a monoenic or dienic aldehyde with a C16
carbon skeleton. For example, the pheromone components
of Diatraea considerata are (Z)-hexadec-11-enal, (Z)-hexa-
dec-7-enal, and (Z)-octadec-13-enal,3 whereas D. grandi-
osella uses (Z)-hexadec-11-enal, (Z)-hexadec-9-enal, and
(Z)-octadec-13-enal as a pheromone blend.4
The sugar cane borer Diatraea saccharalis (Lepi-
doptera: Pyralidae) is an economically important pest of
sugar cane and is distributed from Argentina to Cuba. In
1980 Hammond5 and in 1981 Carney and Lui6 have
reported that the pheromone of D. saccharalis is (9Z,11E)-
hexadecadienal.
A few reports on the synthesis of single isomers of 9,11-
hexadecadienal are found in the literature. Carney and Lui
have synthesized the (9Z,11E)-isomer via the synthetic
intermediates Me3SiO(CH2)8CtCH and (E)-dicyclohexyl-
1-hexenylborane.6
Millar et al. synthesized (9E,11Z)-hexadecadienal for an
investigation of the female-produced sex pheromone of the
pecan nut casebearer, Acrobasis nuxvorella,8 by a synthetic
route wherein the key step was a Heck coupling reaction
between a vinyl iodide and hexyne.
Svirskaya et al. have reported the synthesis of all four
isomers of 9,11-hexadecadienal using four separate routes.9
Many methods are now available for the preparation of
conjugated dienes with high isomeric purity. All have
advantages and limitations. We have used one compound,
11-(tetrahydro-2-pyranyloxy)-2-undecyn-1-ol (9), as starting
material for the synthesis of the four geometric isomers of
9,11-hexadecadienal.
Resu lts a n d Discu ssion
A first step to develop an environmentally safe method
to control D. saccharalis was the unsuccessful test of
(9Z,11E)-hexadecadienal as a trap lure.7 The absence of
any reports of high trap captures in the literature might
be due to a lack of components that, together with the main
compound, would constitute the pheromone blend.
To facilitate the optimization of the pheromone lure of
D. saccharalis, one should investigate the effect of the
geometric isomers of (9Z,11E)-hexadecadienal on male
attraction to the main compound, since the MS analysis
indicated that the gland contained all four geometric
isomers of 9,11-hexadecadienal. Hence we decided to
synthesize the four isomers in order to confirm their
tentative identification and for coming tests of their phero-
monal activity.
Gla n d An a lysis. The following six compounds were
found by dissection and analysis of pheromone glands from
D. saccharalis by means of standard procedures:10 hexa-
decanal, 0.4 ng/female; (Z)-hexadec-11-enal, 0.8 ng/female;
(9E,11Z)-hexadecadienal (E9,Z11-16:Ald), 0.5 ng/female;
(9E,11E)-hexadecadienal (E9,E11-16:Ald), 1.5 ng/female;
(9Z,11E)-hexadecadienal (Z9,E11-16:Ald), 2.5 ng/female;
(9Z,11Z)-hexadecadienal (Z9,Z11-16:Ald) 0.6 ng/female.
The dienes were identified by comparison of the retention
times of the components in the pheromone glands with the
retention times of the synthetic standards (produced as
described below).
The presence of (Z)-hexadec-11-enal was confirmed by
comparison with a commercial reference compound and
agreed with the reports that the compound had also been
found in the glands of the phylogenetically related species
D. grandiosella11 and D. considerata.3
Syn th eses. The four isomers of 9,11-hexadecadienal
were prepared starting from 9-decen-1-ol (5). Protection of
the hydroxyl group of 5 with 3,4-dihydropyran (DHP)
yielded the corresponding tetrahydropyran derivative 6 in
93% yield (Scheme 1). Bromination of compound 6 at -78
°C provided 1,2-dibromo-10-(tetrahydro-2-pyranyloxy)de-
cane (7) in 81% yield. Dehydrobromination of 7 with sodium
amide afforded 1-(tetrahydro-2-pyranyloxy)-9-decyne (8) in
In this paper we report the identification of the four 9,11-
hexadecadienals as well as two, more saturated, analogues
in the glands of D. saccharalis and describe the syntheses
and characterization of all geometrical isomers of 9,11-
hexadecadienal.
* To whom correspondence should be addressed.
† The Royal Institute of Technology.
‡ Swedish University of Agricultural.
§ Universidade Federal de Sa˜o Carlos.
Present address: Department of Chemistry and Biomedical Sciences,
University of Kalmar, SE-391 82 Kalmar, Sweden. Tel: +46-480-446271.
Fax: +46-480-446262. E-mail: rikard.unelius@hik.se.
10.1021/np010551i CCC: $22.00
© 2002 American Chemical Society and American Society of Pharmacognosy
Published on Web 06/08/2002

910 J ournal of Natural Products, 2002, Vol. 65, No. 6
Sch em e 1. Synthesis of the Key Intermediate 9
Santangelo et al.
the product was oxidized (MnO2) to the aldehyde 11
(Scheme 2). The yields were 97% in the reduction step
and 63% in the oxidation step. We believe that the high
yield in the reduction step compared to what is normally
found in the literature for lithium aluminum hydride
reductions is a result of the use of the Baeckstro¨m
procedure for the workup of the reactions.12 The THP-
protected E,E-12 and E,Z-14 dienes were then formed in
separate reactions using normal (E,Z-14/ E,E-12 ) 20:1,
yield 62%) or Schlosser Wittig conditions13 (E,E-12/ E,Z-
14 ) 10:1, yield 61%), respectively. After deprotection of
the E,E-12 and E,Z-14 dienes by means of Amberlyst-15
in methanol, the isomeric purity of the E,E-13 and E,Z-15
was increased to >99% by the urea inclusion complex
(clathrate) procedure14 followed by medium-pressure liquid
chromatography using silica gel impregnated with 10% of
silver nitrate.15
In the final step, (9E,11E)-hexadecadienal (1) and
(9E,11Z)-hexadecadienal (2) were formed by oxidation
using pyridinium dichromate (PDC) in dichloromethane.
The yield was about 70%, and no loss of isomeric purity
was observed.
In the syntheses of (9Z,11E)- and (9Z,11Z)-hexadecadi-
enal (3 and 4, respectively), the key intermediate 9 was
oxidized to the aldehyde 16 by means of MnO2. The yield
was 63%.
The (9Z,11E)-hexadecadienal (3) was produced by a route
starting with a Wittig reaction of the aldehyde 16 with the
ylide prepared from pentyltriphenylphosphonium bromide
using Schlosser conditions (E/ Z ) 7:1).11 The yield of 17
was 61%. Subsequent hydrogenation of the (Z)-enyne (17)
formed yielded the diene 18 in 68% yield. After deprotection
of 18, the isomeric purity of 19 was increased to >99% as
described above for compound 15. Oxidation using PDC in
dichloromethane yielded the Z,E-dienic aldehyde 3 (in 71%
yield) with no loss of isomeric purity.
98% yield. It should be noted that in some experiments the
reaction gave a tribromo adduct, probably dependent on
hydrogen bromide being produced and leading to replace-
ment of the THP group by bromine atom, yielding a
tribromo derivative. The acetylenic proton of compound 8
was removed by means of butyllithium, and paraformal-
dehyde was then added to provide 9 in 66% yield.
The key intermediate 9 was reduced to the corresponding
(E)-allylic alcohol 10 by lithium aluminum hydride, and
Sch em e 2. Syntheses of the Isomers (9E,11E)- and (9E,11Z)-Hexadecadienal

Geometric Isomers of 9,11-Hexadecadienal
J ournal of Natural Products, 2002, Vol. 65, No. 6 911
Sch em e 3. Syntheses of the Isomers (9Z,11E)- and (9Z,11Z)-Hexadecadienal
ethyl acetate. 1H and 13C NMR spectra of CDCl3 solutions were
recorded at 400 and 100 MHz, respectively, using a Bruker
AM spectrometer. Chemical shifts were expressed in ppm in
relation to tetramethylsilane, followed by numbers of protons,
multiplicity (s, singlet; d, doublet; t, triplet; q, quartet; quint,
quintet; m, multiplet; bs, broad singlet; bd, broad doublet; bt,
broad triplet; td, triple doublet; tt, triple triplet; dt, double
triplet) and coupling constants (Hz). The numbers 1′, 2′, 3′,
4′, and 5′ refer to the tetrahydropyran ring. GC-MS analyses
were performed by means of a Finnigan SSQ 7000 mass
spectrometer, connected to a Varian 3400 GC, with electron
impact ionization (EI). A DB-5 MS fused silica column (J &W
Scientific, 30 m, 0.25 mm i.d., 0.25 µm coating layer) and a
DB-wax column (J &W Scientific, 30 m, 0.25 mm i.d., 0.25 µm
coating layer) were used. The injector was a split/splitless type,
closed for 0.5 min at isothermal 225 °C. The elution order of
the dienals was (Z,E), (E,Z), (Z,Z), and (E,E).
The aldehyde 16 was subjected to a normal Wittig
reaction using an ylide prepared from pentyltriphenylphos-
phonium bromide (yield 62%). The product, the enyne THP
ether 20 (Z/ E ) 16:1), was then regio- and stereoselectively
hydrogenated using a sterically hindered borane, and the
(Z,Z)-diene 21 was obtained in 65% yield. After deprotec-
tion, the alcohol 22 was recrystallized at low temperature
(-30 °C) from pentane. This increased the isomeric purity
to >99% with only a small loss of material. Subsequent
oxidation using PDC provided the (Z,Z)-isomer 4 in 71%
yield.
The overall yield of the aldehyde isomers from compound
9 was in the range 17-26%.
Exp er im en ta l Section
Sou r ce of Biologica l Ma ter ia ls. Field-collected pupae
(from Campos dos Goytacazes, Rio de J aneiro State, Brazil)
were placed in 10 × 10 × 10 cm cages for emergence. They
were held in the laboratory under a photoperiod of 14:8 (L:D)
h. The pheromone glands were then excised from the extruded
ovipositors of 2 to 3 day old calling virgin females during the
first 3 h of the scotophase and were extracted in batches of
19-43 (n ) 3) during 1 min, in 5-7 µL of redistilled heptane.
The compounds extracted were identified using a Hewlett-
Packard 5970B (Hewlett-Packard, Palo Alto, CA) mass spec-
trometer (MS) with electron impact (EI) ionization, which was
interfaced with a Hewlett-Packard 5890 gas chromatograph
(GC), with a polar DB-wax column (30 m × 0.25 mm, J &W
Scientific, Folsom, CA). In addition, the retention times of the
identified gland compounds were compared with those of
synthetic compounds on a Hewlett-Packard 5890 GC, with
flame ionization detection, on a DB-wax column and on a
nonpolar SE-54 column (25 m × 0.32 mm; Kupper & Co.,
Bonaduz, Switzerland).
The tetrahydrofuran (THF) was treated with sodium/benzo-
phenone and distilled immediately before use. The dichloro-
methane (CH2Cl2) was treated with calcium hydride and,
likewise, distilled immediately before use. The other starting
materials employed were purchased from commercial suppliers
and used without further purification. The reactions involving
anhydrous solvents were carried out under an atmosphere of
argon.
1-(Tetr a h yd r o-2-p yr a n yloxy)-9-d ecen e (6). Amberlyst-
15 (0.88 g) was added at 0 °C to a solution of 9-decen-1-ol (5)
(4.30 g, 27.0 mmol) in diethyl ether (80 mL) and followed by
3,4-dihydro-2H-pyran (DHP) (2.95 mL, 32.0 mmol). The reac-
tion mixture was stirred for 3 h, the resin was filtered off, and
the solution was concentrated. Purification by liquid chroma-
tography afforded the THP ether 6 in 93% yield (6.15 g): 1H
NMR (CDCl3, 400 MHz) δ 5.79 (1H, ddt, J ) 17.1 Hz, J )
10.0 Hz, J ) 6.7 Hz, H-9), 4.96 (1H, ddt, J ) 17.1 Hz, J ) 2.1
Hz, J ) 1.5 Hz, H-10), 4.90 (1H, ddt, J ) 10.0 Hz, J ) 2.1 Hz,
J ) 1.5 Hz, H-10), 4.55 (1H, t, J ) 3.5 Hz, O-CH-O), 3.85
(1H, ddd, J ) 11.1 Hz, J ) 7.4 Hz, J ) 3.6 Hz, Haxial-5′), 3.71,
3.35 (each 1H, dt, J ) 9.4 Hz, 6.6 Hz, H-1), 3.50-3.45 (1H, m,
Exp er im en ta l P r oced u r es. The preparative liquid chro-
matography technique used was the one described by Baeck-
stro¨m et al.16 It was performed on silica gel (Merck 60, 0.040-
0.063 mm) in 15 or 25 mm inner diameter glass columns with
gradient elution, using hexane and increasing proportions of
H
equat-5′), 2.00 (2H, q, J ) 6.7 Hz, H-8), 1.85-1.77 (1H, m),
1.68 (1H, tt, J ) 9.4 Hz, J ) 3.6 Hz), 1.59-1.47 (6H, m), 1.35-
1.27 (10H, m); 13C NMR (CDCl3, 100 MHz) 139.16 (C-9), 114.06

912 J ournal of Natural Products, 2002, Vol. 65, No. 6
Santangelo et al.
(C-10), 98.79 (O-CH-O), 67.62, (C-1), 62.27 (C-5′), 33.76 (C-
8), 30.74 (C-2 and C-2′), 29.38 (2C), 29.03, 28.86, 26.18 (C-3),
25.46 (C-4′), 19.63 (C-3′); EIMS m/z [M]+ 240 (0.2), 101 (25),
85 (100), 83 (13), 69 (10), 67 (11), 57 (9), 56 (16), 55 (26), 43
(8), 42 (3), 41 (26), 39 (5).
10H2O and Celite (1:1, v:v). The slurry was filtered through a
1 cm Celite bed on a Bu¨chner funnel. The Celite bed was
washed thoroughly with hexane (3 × 20 mL). The combined
organic phases were dried with MgSO4, and the solvents were
evaporated under reduced pressure. The yield after chroma-
tography was 97% (2.6 g): 1H NMR (CDCl3, 400 MHz) δ 5.58
(1H, dt, J ) 15.5 Hz, J ) 6.7 Hz, H-3), 5.62-5.48 (1H, m, H-2),
4.49 (1H, t, J ) 2.7 Hz, H-1′), 3.96 (2H, t, J ) 5.2 Hz, H-1),
3.78 (1H, ddd, J ) 11.4 Hz, J ) 7.7 Hz, J ) 3.4 Hz, Haxial-5′),
3.63, 3.29 (each 1H, dt, J ) 9.4 Hz, 6.8 Hz, H-11), 3.43-3.38
(1H, m, Hequat-5′), 2.53 (1H, t, J ) 5.2 Hz, OH), 1.94 (2H, app.
q, J ) 6.7 Hz, H-4), 1.77-1.69 (1H, m), 1.61 (1H, m), 1.51-
1.41 (6H, m), 1.28-1.20 (10H, m); 13C NMR (CDCl3, 100 MHz)
δ 132.64 (C-3), 128.85 (C-2), 98.50 (O-CH-O), 67.41 (C-11),
63.20 (C-1), 61.97 (C-5′), 31.97 (C-4), 30.48 (C-2′), 29.45, 29.16
(2C), 28.87 (2C), 25.96, 25.24, 19.35 (C-3′); EIMS m/z 237 (4),
107 (5), 101 (36), 95 (10), 93 (11), 85 (100), 84 (13), 83 (8), 81
(13), 79 (14), 77 (6), 70 (9), 69 (7), 67 (21), 56 (9), 55 (27), 43
(10), 41 (29), 39 (8).
9,10-Dibr om o-1-(tetr a h yd r o-2-p yr a n yloxy)d eca n e (7).
Bromine was added dropwise to compound 6 (6.15 g, 25.7
mmol) in CH2Cl2 (65 mL) at -78 °C until the first persistence
of the halogen color. The solution was shaken with Na2SO3
(10% aqueous solution, 3 × 50 mL), and the organic phase was
finally washed with brine and dried (MgSO4). The desired
compound (7) was obtained in 81% yield (8.20 g): 1H NMR
(CDCl3, 400 MHz) δ 4.54 (1H, t, J ) 6.7 Hz, O-CH-O), 4.13
(1H, tt, J ) 9.1 Hz, J ) 4.0 Hz, H-9), 3.85-3.80 (1H, m, Haxial
-
5′), 3.82 (1H, dd, J ) 10.1 Hz, J ) 4.0 Hz, H-10), 3.70, 3.35
(each 1H, dt, J ) 9.4 Hz, J ) 6.7 Hz, H-1), 3.59 (1H, t, J )
10.1 Hz, H-10), 3.48-3.42 (1H, m, Hequat-5′), 2.13-2.03 (1H,
m), 1.84-1.64 (3H, m), 1.55-1.48 (6H, m), 1.31-1.26 (10H,
m); 13C NMR (CDCl3, 100 MHz) 98.73 (O-CH-O), 67.52 (C-
1), 62.23 (C-5′), 53.02 (C-9), 36.27 (C-8), 35.91 (C-10), 30.70
(C-2 and C-2′), 29.24 (2C), 29.21, 28.65, 26.63 (C-3), 25.43 (C-
4′), 19.61 (C-3′); EIMS m/z 401 [M]+ (1), 400 (3), 399 (2), 137
(9), 109 (5), 101 (5), 95 (11), 85 (100), 84 (8), 83 (6), 81 (12), 69
(13), 67 (16), 57 (13), 56 (21), 55 (31), 53 (9), 43 (8), 42 (6), 41
(37), 39 (9).
11-(Tet r a h yd r o-2-p yr a n yloxy)-(E)-u n d ec-2-en a l (11).
An excess of MnO2 was added to a solution of 10 (2.5 g, 9.3
mmol) in CH2Cl2 (20 mL). The mixture was stirred at room
temperature for 2 h, and the residues containing manganese
were filtered off. The yield of the protected alkenal 11 after
chromatography was 63% (1.56 g): 1H NMR (CDCl3, 400 MHz)
δ 9.42 (1H, dd, J ) 7.9 Hz, J ) 1.5 Hz, CHO), 6.78 (1H, dt, J
) 15.5 Hz, J ) 6.86 Hz, H-3), 6.02 (1H, ddt, J ) 15.5 Hz, J )
7.9 Hz, J ) 1.5 Hz, H-2), 4.48 (1H, t, J ) 3.3 Hz, O-CH-O),
3.78 (1H, ddd, J ) 9.0 Hz, J ) 7.2 Hz, J ) 3.4 Hz, Haxial-5′),
3.64, 3.30 (each 1H, dt, J ) 9.5 Hz, 6.9 Hz, H-11), 3.43-3.38
(1H, m, Hequat-5′), 2.25 (2H, q, J ) 7.0 Hz, H-4), 1.77-1.70 (1H,
1-(Tetr ah ydr o-2-pyr an yloxy)-9-decyn e (8). Sodium amide
(1.95 g, 50.1 mmol) in THF (25 mL) was slowly added to
compound 7 (8.20 g, 20.0 mmol) in THF (60 mL) at -78 °C.
The reaction mixture was refluxed overnight and then neu-
tralized with aqueous HCl (10%) (3 × 50 mL). The organic
layer was separated and dried (MgSO4). The yield of the
protected alkynol 8 after chromatography was 98% (4.66 g):
1H NMR (CDCl3, 400 MHz) 4.47 (1H, t, J ) 4.2 Hz, O-CH-
m), 1.66-1.60 (1H, m), 1.52-1.41 (6H, m), 1.24 (10H, bs); 13
C
NMR (CDCl3, 100 MHz) δ 193.90 (CHO), 158.82 (C-3), 132.78
(C-2), 98.67 (C-1′), 67.40 (C-11), 62.15 (C-5′), 32.53 (C-4), 30.61
(C-2′), 29.53 (s. C-10), 29.12, 29.09, 28.88, 27.62, 25.99 (C-4′),
25.31 (C-9), 19.53 (C-3′); EIMS m/z 268 [M]+ (0.5), 267 [M -
H]+ (0.7), 107 (6), 101 (46), 95 (6), 93 (11), 85 (100), 84 (7), 83
(9), 82 (6), 81 (12), 79 (8), 70 (11), 67 (18), 57 (22), 56 (14), 55
(53), 54 (9), 43 (17), 42 (8), 39 (13), 32 (10).
O), 3.75 (1H, ddd, J ) 11.1 Hz, J ) 7.7 Hz, J ) 3.4 Hz, Haxial
-
5′), 3.62, 3.28 (each 1H, dt, J ) 9.4 Hz, J ) 6.7 Hz, J ) 3.5
Hz, H-1), 3.41-3.34 (1H, m, Hequat-5′), 2.07 (2H, td, J ) 7.1
Hz, J ) 2.6 Hz, H-8), 1.83 (1H, t, J ) 2.6 Hz, CtCH), 1.77-
1.69 (1H, m), 1.63-1.57 (1H, m), 1.49 (4H, m), 1.42 (2H, quint,
J ) 7.1 Hz, H-7), 1.34-1.22 (m, 10H); 13C NMR (CDCl3, 100
MHz) δ 98.52 (C-1′), 84.28 (C-9), 67.94 (C-1), 67.31 (C-10),
61.91 (C-5′), 30.59 (C-2 and C-2′), 29.54, 29.10, 28.47 (2C),
26.01 (C-3), 25.37 (C-4′), 19.44 (C-3′), 18.15 (C-8); EIMS m/z
237 [M - H]+ (1), 101 (31), 95 (10), 86 (5), 85 (100), 84 (6), 81
(15), 79 (6), 67 (14), 56 (15), 55 (17), 41 (19).
1-(Tetr a h yd r o-2-p yr a n yloxy)-(9E,11E)-h exa d eca d ien e
(12). 1-Pentyltriphenylphosphonium bromide (1.09 g, 2.63
mmol) was suspended in THF (4.4 mL) and diethyl ether (2.6
mL) and stirred with BuLi (1.08 M in hexane, 2.44 mL, 2.63
mmol) for 15 min. The solution was cooled to -70 °C, and the
aldehyde 11 (0.7 g, 2.6 mmol), dissolved in diethyl ether (1.75
mL), was added. The mixture was stirred vigorously until the
yellow coloration disappeared (5 min at -70 to -40 °C), and
an additional amount of BuLi (1.08 M, 2.44 mL, 2.63 mmol)
was added. The reaction mixture was then stirred at -30 °C
for 5 min, whereupon a solution of hydrogen chloride in diethyl
ether (1 M, 2.89 mmol, 2.89 mL) and then potassium tert-
butoxide (0.44 g, 3.95 mmol) in 2-methyl-2-propanol (0.45 mL,
3.95 mmol) were added. The mixture was then stirred at room
temperature for 2 h, washed with water until it remained
neutral, and dried (MgSO4). After evaporation of the solvent,
the crude product (E,E-12:E,Z-14, 10:1) was subjected to
medium-pressure column chromatography, yielding 61% (2.7
g) of a 10:1 mixture of the E,E-diene 12 and the E,Z-diene
-14: 1H NMR (CDCl3, 400 MHz) of 12 δ 5.94 (2H, dd, J ) 12.5
Hz, J ) 1.7 Hz, H-10 and H-11), 5.49-5.46 (2H, m, H-9 and
H-12), 4.49 (1H, s, O-CH-O), 3.81-3.76 (1H, ddd, J ) 11.0
Hz, 7.3 Hz, J ) 3.3, Haxial-5′), 3.65, 3.29 (each 1H, dt, J ) 9.7
Hz, J ) 6.7 Hz, H-1), 3.43-3.40 (1H, m, Hequat-5′), 1.97-1.96
(4H, bs), 1.76-1.74 (1H, m), 1.69-1.57 (1H, m), 1.51-1.45
(6H, m), 1.26-1.21 (14H, m), 0.83-0.80 (3H, bs, CH3); 13C
NMR (CDCl3, 100 MHz) 132.34 (C-9 and C-12), 130.32 (C-10
and C-11), 98.82 (O-CH-O), 67.65 (C-1), 62.30 (C-5′), 32.57
(C-8 or C-13), 32.24 (C-2′), 31.57 (C-8 or C-13), 30.78 (C-14),
29.73, 29.42, 29.40 (2C), 29.14, 26.21 (C-4′), 25.50 (C-3), 22.22
(C-15), 19.68 (C-3′), 13.91 (CH3); EIMS m/z 322 [M]+ (2), 304
(8), 101 (9), 95 (17), 93 (9), 85 (100), 81 (23), 79 (15), 67 (29),
57 (10), 54 (30), 43 (11), 41 (20).
11-(Tetr a h yd r o-2-p yr a n yloxy)u n d ec-2-yn -1-ol (9). Bu-
tyllithium (2.5 M in hexane, 9.94 mL) was added dropwise to
an ice-cold solution of the protected alkynol 8 (3.94 g, 16.6
mmol) in THF (25 mL), and the mixture was stirred under
inert atmosphere for 40 min. Paraformaldehyde (0.74 g, 24.9
mmol) was added in one portion, and the mixture was kept at
reflux for 3 h. After cooling and addition of ice-water (20 mL),
the organic material was extracted with ethyl acetate (3 × 50
mL). The ethyl acetate extracts were combined, washed with
aqueous ammonium chloride (2 × 50 mL), dried (MgSO4), and
concentrated under reduced pressure. The crude compound
was subjected to medium-pressure liquid chromatography. The
yield of 9 was 61% (2.7 g): 1H NMR (CDCl3, 400 MHz) δ 4.51
(1H, t, J ) 3.0 Hz, O-CH-O), 4.15 (2H, bs, H-1), 3.80 (1H,
ddd, J ) 10.9 Hz, J ) 7.4 Hz, J ) 3.5 Hz, Haxial-5′), 3.65, 3.32
(each 1H, dt, J ) 9.7 Hz, 6.7 Hz, H-11), 3.48-3.40 (1H, m,
H
equat-5′), 2.42 (1H, bs, OH), 2.14 (2H, tt, J ) 7.0 Hz, J ) 2.1
Hz, H-4), 1.81-1.72 (1H, m), 1.64 (1H, m), 1.56-1.38 (6H, m),
1.35-1.22 (10H, m); 13C NMR (CDCl3, 100 MHz) 98.61 (O-
CH-O), 85.84 (C-3), 78.45 (C-2), 67.46 (C-11), 62.04 (H-5′),
50.85 (C-1), 30.54 (C-2′), 29.49, 29.09, 28.82, 28.56, 28.41, 25.96
(C-7), 25.31 (C-9), 19.41 (C-3′), 18.52 (C-4); EIMS m/z 268 [M]+
(0.14), 267 [M - H]+ (0.9), 101 (36), 95 (6), 91 (4), 86 (4), 85
(100), 83 (6), 81 (11), 79 (9), 70 (5), 69 (6), 67 (14), 57 (13), 55
(7), 43 (4), 41 (7).
11-(Tetr a h yd r o-2-p yr a n yloxy)-(E)-u n d ec-2-en -1-ol (10).
A solution of compound 9 (2.66 g, 9.93 mmol) in THF (6.5 mL)
was added dropwise to a suspension of LiAlH4 (0.38 g, 9.93
mmol) in THF (10 mL). The resulting mixture was stirred at
room temperature for 12 h, and the reaction was then
quenched by careful addition of 5 g of a mixture of Na2SO4‚
(9E,11E)-Hexa d eca d ien -1-ol (13). Amberlyst-15 (0.23 g)
was added to a solution of E,E-12:E,Z-14 (10:1) (2.5 g, 7.8
mmol) in MeOH (15.5 mL). The mixture was stirred at 45 °C

Geometric Isomers of 9,11-Hexadecadienal
J ournal of Natural Products, 2002, Vol. 65, No. 6 913
for 40 min, the resin was filtered off, and the solution was
dried and concentrated under reduced pressure. The yield of
the 10:1 mixture of the alcohols 13 and 15 after chromatog-
raphy was 97% (1.79 g): 1H NMR (CDCl3, 400 MHz) of 13 δ
6.02 (2H, d, J ) 17.1 Hz, H-10 and H-11), 5.61-5.56 (2H, m,
H-9 and H-12), 3.66 (2H, t, J ) 5.3 Hz, H-1), 2.19 (1H, s, OH),
2.07 (4H, m, H-8 and H-13), 1.61-1.57 (2H, m, H-2), 1.31-
1.26 (14H, m), 0.91 (3H, t, J ) 5.7 Hz, CH3); 13C NMR (CDCl3,
100 MHz) δ 132.5 (C-12 or C-9), 132.4 (C-12 or C-9), 130.4 (C-
10 and C-11), 63.1 (C-1), 32.8 (C-2), 32.6 (C-8 or C-13), 32.3
(C-8 or C-13), 31.6 (C-14), 29.4 (3C), 29.1, 25.7 (C-3), 22.3 (C-
15), 14.0 (CH3); EIMS m/z 238 [M]+ (16), 136 (12), 135 (10),
124 (8), 122 (6), 121 (5), 110 (12), 109 (15), 108 (10), 107 (7),
98 (9), 97 (7), 96 (22), 95 (9), 94 (23), 93 (21), 92 (7), 91 (17), 83
(9), 82 (31), 81 (45), 80 (40), 79 (50), 77 (11), 68 (14), 67 (97),
66 (10), 65 (11), 57 (9), 56 (6), 55 (61), 54 (9), 53 (22), 51 (10),
41 (63), 39 (18), 31 (100).
or C-12), 128.6 (C-10 or C-11), 125.57 (C-10 or C-11), 98.78
(C-1′), 67.61 (C-1), 62.25 (C-5′), 32.82 (C-8), 31.85 (C-2′), 30.73
(C-14), 29.68, 29.39 (2C), 29.35, 29.13, 27.33 (C-13), 26.18 (C-
4′), 25.46 (C-3), 22.26 (C-15), 19.64 (C-3′), 13.91 (CH3); EIMS
m/z 322 [M]+ (1), 238 (7), 124 (10), 122 (9), 101 (17), 96 (15),
85 (100), 81 (21), 78 (14), 67 (43), 55 (24), 54 (15), 43 (14), 41
(26).
(9E,11Z)-Hexa d eca d ien -1-ol (15). The alcohol 15 was
prepared from compound 14/compound 12 (20:1) by the same
procedure (see above) as was used to hydrolyze compound 12/
14 (10:1) to compound 13. The yield was 97%: 1H NMR (CDCl3,
400 MHz) δ 6.27 (1H, ddq, J ) 15.5 Hz, J ) 11.0 Hz, J ) 1.24
Hz, H-11), 5.92 (1H, t, J ) 11.0 Hz, H-10), 5.62 (1H, dt, J )
15.26, J ) 7.0 Hz, H-12), 5.27 (1H, dt, J ) 11.0 Hz, 7.3 Hz,
H-9), 3.60 (2H, t, J ) 6.7 Hz, H-1), 2.15 (1H, s, OH), 2.14 (2H,
q, J ) 7.3 Hz, H-8), 2.06 (2H, q, J ) 7.0 Hz, H-13), 1.53 (2H,
q, J ) 6.7 Hz, H-2), 1.36-1.28 (14H, m), 0.88 (3H, t, J ) 7.0
Hz, CH3); 13C NMR (CDCl3, 100 MHz) δ 134.52 (C-9 or C-12),
130.0 (C-9 or C-12), 128.56 (C-10 or C-11), 125.62 (C-10 or
C-11), 62.95 (C-1), 32.80 (C-2 or C-8), 32.73 (C-2 or C-8), 31.86
(C-14), 29.41, 29.33 (2C), 29.10, 27.35 (C-13), 25.69 (C-3), 22.27
(C-15), 13.89 (CH3); EIMS m/z 238 [M]+ (8), 135 (10), 110 (12),
109 (15), 108 (10), 107 (7), 98 (9), 97 (7), 96 (22), 95 (9), 94
(23), 93 (21), 92 (7), 91 (17), 83 (9), 82 (31), 81 (45), 80 (40), 79
(50), 77 (11), 68 (14), 67 (97), 66 (10), 65 (11), 57 (9), 56 (6), 55
(61), 54 (9), 53 (22), 51 (10), 45 (7), 44 (5), 43 (18), 42 (7), 41
(42), 39 (10), 31 (100).
Ur ea In clu sion Com p lexes. In
a typical experiment
impure (9E,11E)-hexadecadien-1-ol (13) (91% isomeric purity)
(1.25 g, 5.25 mmol) was mixed with a hot solution of urea (1.89
g, 31.5 mmol) in methanol (10 mL). The resulting solution was
allowed to cool to room temperature before it was left in the
refrigerator overnight. The resulting crystals were rapidly
filtered off. The clathrate was dissolved in brine and extracted
with diethyl ether. Drying and concentration gave a mixture
(1.2 g) containing 97% of the (E,E)-isomer together with 3%
of the (E,Z)-isomer. This mixture was subjected to medium-
pressure liquid chromatography, using silica gel impregnated
with 10% of silver nitrate and yielding the (E,E)-isomer in
>99% isomeric purity.
(9E,11Z)-Hexa d eca d ien a l (2). The dienal 2 was prepared
from the dienol 15 as described before (see preparation of
compound 1 from 13) in an isomeric purity of >99% and 70%
1
(9E,11E)-Hexa d eca d ien a l (1). The alcohol 13 (1.5 g, 6.3
mmol) was stirred overnight with a slurry of pyridinium
dichromate (4.72 g, 12.6 mmol) in CH2Cl2 (12 mL). The mixture
was then diluted with hexane and filtered through Celite. The
filtrate was concentrated and subjected to medium-pressure
column chromatography, yielding 71% (1.0 g) of the E,E-dienal
yield: H NMR (CDCl3, 400 MHz) δ 9.75 (1H, t, J ) 1.8 Hz,
CHO), 6.28 (1H, ddq, J ) 15.0 Hz, J ) 11.0 Hz, J ) 1.24 Hz,
H-11), 5.92 (1H, t, J ) 11.0 Hz, H-10), 5.63 (1H, dt, J ) 15.0
Hz, J ) 7.0 Hz, H-12), 5.29 (1H, dt, J ) 11 Hz, J ) 7.6 Hz,
H-9), 2.40 (2H, td, J ) 7.3 Hz, J ) 1.8 Hz, H-2), 2.15 (2H, q,
J ) 7.3 Hz, H-8), 2.07 (2H, q, J ) 7.0 Hz, H-13), 1.63 (2H,
quint, J ) 7.26 Hz, H-3), 1.38-1.22 (12H, m), 0.89 (3H, t, J )
7.0 Hz, CH3); 13C NMR (CDCl3, 100 MHz) δ 202.93 (CHO),
134.45 (C-9 or C-12), 130.17 (C-9 or C-12), 128.52 (C-10 or
C-11), 125.65 (C-10 or C-11), 43.89 (C-2), 32.81 (C-8 or C-14),
31.89 (C-8 or C-14), 30.93, 29.29, 29.19, 29.09, 27.38 (C-13),
22.31 (C-15), 22.04 (C-3), 13.96 (CH3); EIMS m/z 236 [M]+ (29),
175 (10), 151 (10), 147 (12), 137 (15), 135 (25), 124 (10), 111
(12), 110 (20), 109 (26), 108 (13), 107 (13), 98 (12), 97 (16), 96
(32), 95 (34), 94 (17), 93 (13), 91 (16), 83 (16), 82 (39), 81 (82),
80 (26), 79 (50), 77 (10), 69 (14), 68 (26), 67 (100), 66 (17), 55
(34), 55 (48), 54 (41), 45 (20), 4 (19), 42 (75); HREIMS m/z
236.214348 (calcd for C16H28O, 236.214016).
1
1 in an isomeric purity of >99%: H NMR (CDCl3, 400 MHz)
δ 9.75 (1H, t, J ) 1.76 Hz, CHO), 6.01 (2H, d, J ) 17 Hz, H-10
and H-11), 5.6-5.55 (2H, m, H-9 and H-12), 2.40 (2H, td, J )
7.3 Hz, J ) 1.85 Hz, H-2), 2.1 (4H, m, H-8 and H-13), 1.6 (2H,
quint, J ) 7.3 Hz, H-3), 1.3-1.25 (12H, m), 0.9 (3H, t, J ) 5.7
Hz, CH3); 13C NMR (CDCl3, 100 MHz) δ 202.90 (CHO), 132.4
(C-9 or C-12), 132.3 (C-9 or C-12), 130.4 (C-10 and C-11), 43.89
(C-2), 32.5 (C-8 or C-13), 32.3 (C-8 or C-13), 31.6 (C-14), 29.5,
29.4 (2C), 29.1, 22.3 (C-15), 22.03 (C-3), 14.03 (CH3); EIMS
m/z 236 [M]+ (69), 150 (12), 133 (11), 124 (15), 123 (10), 122
(11), 121 (15), 111 (14), 110 (19), 109 (13), 98 (18), 97 (13), 96
(31), 95 (32), 94 (13), 93 (18), 91 (17), 82 (22), 81 (55), 80 (23),
79 (46), 77 (18), 69 (14), 68 (24), 67 (100), 65 (16), 55 (54), 54
(33), 44 (15), 43 (29), 42 (22), 41 (75); HREIMS m/z 236.214550
(calcd for C16H28O, 236.214016).
11-(Tetr a h yd r o-2-p yr a n yloxy)u n d ec-2-yn a l (16). The
compound 16 was prepared from compound 9 as described
before (see oxidation of compound 10 to compound 11) in 63%
yield: 1H NMR (CDCl3, 400 MHz) δ 9.15 (1H, s, CHO), 4.54
(1H, t, J ) 3.9 Hz, OCHO), 3.86-3.81 (1H, m, Haxial-5′), 3.70,
3.36 (each 1H, dt, J ) 9.2 Hz, J ) 7.0 Hz, H-1), 3.49-3.45
(1H, m, Hequat-5′), 2.38 (2H, t, J ) 7.0 Hz, H-4),1.82-1.77 (1H,
m), 1.71-1.66 (1H, m), 1.58-1.51 (6H, m), 1.39-1.29 (10H,
m); 13C NMR (CDCl3, 100 MHz) δ 177.31 (C-1), 98.85 (C-1′),
98.80 (C-3), 81.64 (C-2), 67.58 (C-11), 62.30 (C-5′), 30.68 (C-
2′), 29.62, 29.18, 28.87, 28.69, 27.43 (C-5), 26.10 (C-4′), 25.40
(C-9), 19.59 (C-3′), 19.06 (C-4); EIMS m/z 266 [M]+ (2), 105
(14), 101 (22), 100 (8), 95 (15), 94 (6), 93 (6), 91 (6), 85 (7), 85
(100), 84 (8), 81 (13), 80 (9), 79 (21), 69 (6), 68 (7), 67 (19), 66
(10), 64 (8), 57 (11), 56 (25), 55 (13), 55 (14), 53 (14), 52 (8), 49
(6), 44 (5), 43 (12), 41 (9), 41 (65), 40 (16), 39 (10), 38 (23).
1-(Tetr a h yd r o-2-p yr a n yloxy)-(E)-h exa d ec-11-en -9-yn e
(17). Compound 17 was prepared from compound 16 as
described before (see preparation of compound 12 from 11).
The process yielded 61% of a mixture containing 7:1 of E-17
and Z-20: 1H NMR (CDCl3, 400 MHz) of 17 δ 6.03 (1H, dt, J
) 15.8 Hz, J ) 7.1 Hz, H-12), 5.44 (1H, dq, J ) 15.8 Hz, J )
1.8 Hz, H-11), 4.57 (1H, dd, J ) 4.4 Hz, J ) 2.6 Hz, OCHO),
3.87 (1H, ddd, J ) 11.0 Hz, J ) 7.4 Hz, J ) 3.5 Hz, Haxial-5′),
3.73, 3.38 (each 1H, dt, J ) 9.5 Hz, 6.9 Hz, H-1), 3.52-3.47
(1H, m, Hequat-5′), 2.27 (2H, td, J ) 7.0 Hz, J ) 1.8 Hz, H-8),
2.07 (2H, q, J ) 7.0 Hz, H-13), 1.86-1.79 (1H, m), 1.71 (1H,
1-(Tetr a h yd r o-2-p yr a n yloxy)-(9E,11Z)-h exa d eca d ien e
(14). 1-Pentyltriphenylphosphonium bromide (1.14 g, 2.76
mmol) in THF (3.5 mL) was added to a solution of potassium
bis[trimethylsilyl]amide (0.5 M in toluene, 19.56 mL, 9.78
mmol). After refluxing for 1 h the reaction mixture was cooled
to -78 °C, and a solution of the aldehyde 11 (1.1 g, 4.14 mmol)
in THF (3.5 mL) was added dropwise. The mixture was then
stirred for 3 h, before it was poured into aqueous NH4Cl (10%,
20 mL). The organic phase was separated and the aqueous
phase extracted with hexane. The combined organic phases
were dried with MgSO4. After evaporation, the crude product
(E,Z-14:E,E-12, 20:1) was subjected to medium-pressure col-
umn chromatography, yielding 62% (0.82 g) of a 20:1 mixture
of the E,Z-diene 14 and the E,E-diene 12: 1H NMR (CDCl3,
400 MHz) of 14 δ 6.27 (1H, ddq, J ) 15.2 Hz, J ) 11.0 Hz, J
) 1.24 Hz, H-11), 5.91 (1H, t, J ) 10.9 Hz, H-10), 5.62 (1H,
dt, J ) 15.0 Hz, J ) 7.3 Hz, H-12), 5.27 (1H, dt, J ) 11.0 Hz,
J ) 7.3 Hz, H-9), 4.44 (1H, t, J ) 2.4 Hz, O-CH-O), 3.85
(1H, ddd, J ) 11.0 Hz, 7.3 Hz, J ) 3.3, Haxial-5′), 3.71, 3.34
(each 1H, dt, J ) 9.7 Hz, J ) 6.7 Hz, H-1), 3.50-3.44 (1H, m,
H
equat-5′), 2.14 (2H, q, J ) 7.3 Hz, H-8), 2.06 (2H, q, J ) 7.3
Hz, H-13), 1.84-1.76 (1H, m), 1.72-1.66 (1H, m), 1.59-1.47
(6H, m), 1.34-1.27 (14H, m), 0.88 (3H, t, J ) 7.2 Hz, H-16);
13C NMR (CDCl3, 100 MHz) δ 134.55 (C-9 or C-12), 129.97 (C-9

914 J ournal of Natural Products, 2002, Vol. 65, No. 6
Santangelo et al.
m), 1.61-1.47 (6H, m), 1.39-1.32 (14H, m), 0.88 (3H, t, J )
7.1 Hz, CH3); 13C NMR (CDCl3, 100 MHz) δ 143.33 (C-12),
109.81 (C-11), 98.85 (OCHO), 88.65 (C-9), 79.20 (C-10), 67.66
(C-1), 62.34 (C-5′), 32.66 (C-13), 30.98 (C-14), 30.79, 29.75,
29.37, 29.12, 28.87 (2C), 26.22 (C-4′), 25.52 (C-3), 22.16 (C-
15), 19.71 (C-3′), 19.35 (C-8), 13.89 (CH3); EIMS m/z 320 [M]+
(5), 249 (11), 122 (19), 121 (12), 95 (9), 91 (15), 85 (100), 79
(29), 78 (14), 77 (20), 67 (16), 57 (21), 56 (20), 55 (19), 43 (18),
41 (13).
Dicycloh exylbor a n e. The temperature was kept between
-5 and -10 °C, while a solution of borane in tetrahydrofuran
(1 M, 3.1 mL, 3.1 mmol) was added slowly over a period of 30
min to a solution of cyclohexene (0.51 g, 6.2 mmol) in THF (3
mL). The resultant milky solution was stirred at 0 to -10 °C
for 2 h and then used as such in the next step.
1-(Tetr a h yd r o-2-p yr a n yloxy)-(9Z,11E)-h exa d eca d ien e
(18). A solution of compound 17 (0.45 g, 1.4 mmol) in THF
(2.5 mL) was added dropwise to the above dicyclohexylborane
solution (3.1 mmol) at -20 °C. The suspension was stirred at
approximately -15 °C for 2 h and then allowed to reach room
temperature. After 2 h of stirring at room temperature the
precipitate of dicyclohexylborane had disappeared. Glacial
acetic acid (1.3 mL) was then added to the mixture, which was
stirred overnight at 45 °C. Oxidation of the resulting dicyclo-
hexylborinate was achieved by addition of sodium hydroxide
(6 M, 5 mL) followed by dropwise addition of hydrogen peroxide
(35%, 1.4 mL) at a rate maintaining the reaction mixture at
30-35 °C. The mixture was stirred for an additional 30 min
and was then poured into ice-water (15 mL), extracted with
hexane (4 × 30 mL), dried (MgSO4), and chromatographed,
providing the desired compound 18 in 65% yield: 1H NMR
(CDCl3, 400 MHz) δ 6.31-6.25 (1H, m, H-11), 5.92 (1H, t, J )
10.9 Hz, H-10), 5.64 (1H, dt, J ) 15 Hz, J ) 7.2 Hz, H-12),
5.34-5.24 (1H, m, H-9), 4.56 (1H, bs, OCHO), 3.86 (1H, ddd,
J ) 11.0 Hz, J ) 7.7 Hz, J ) 3.4 Hz, Haxial-5′), 3.71, 3.36 (each
65 (8), 57 (16), 55 (7), 53 (15), 44 (64), 44 (36), 42 (26), 41 (100),
39 (15), 32 (19); HREIMS m/z 236.220520 (calcd for C16H28O,
236.214016).
1-(Tetr a h yd r o-2-p yr a n yloxy)-(Z)-h exa d ec-11-en -9-yn e
(20). Compound 20 was prepared, from the aldehyde 16, in
the same manner as compound 14 was prepared from com-
pound 11. The product obtained was a 62% yield of a mixture
containing 20:1 Z-20 and E-17: 1H NMR (CDCl3, 400 MHz)
of 20 δ 5.78 (1H, dt, J ) 10.7 Hz, J ) 7.3 Hz, H-12), 5.40 (1H,
bd, J ) 10.7 Hz, H-11), 4.55 (1H, dd, J ) 4.4 Hz, J ) 2.4 Hz,
OCHO), 3.87-3.82 (1H, m, Haxial-5′), 3.70, 3.35 (each 1H, dt,
J ) 9.7 Hz, J ) 6.7 Hz, H-1), 3.50-3.45 (1H, m, Hequat-5′), 2.32
(2H, td, J ) 7.0 Hz, J ) 1.8 Hz, H-8), 2.26 (2H, td, J ) 7.2 Hz,
J ) 1.2 Hz, H-13), 1.84-1.76 (1H, m), 1.68 (1H, m), 1.6-1.45
(6H, m), 1.4-1.3 (14H, m), 0.88 (3H, t, J ) 6.7 Hz, CH3); 13C
NMR (CDCl3, 100 MHz) δ 142.58 (C-12), 109.26 (C-11), 98.80
(OCHO), 94.36 (C-9), 79.10 (C-10), 67.62 (C-1), 62.31 (C-5′),
31.01 (C-14), 30.74, 29.71, 29.68, 29.36, 29.07, 28.81, 28.78 (C-
13), 26.18 (C-4′), 25.46 (C-3), 22.2 (C-15), 19.67 (C-3′), 19.47
(C-8), 13.89 (CH3); EIMS m/z 320 [M]+ (7), 122 (11), 121 (6),
119 (9), 95 (9), 93 (10), 91 (21), 85 (100), 81 (10), 80 (11), 79
(33), 78 (12), 77 (15), 67 (21), 65 (6), 57 (13), 56 (12), 55 (22),
43 (16), 41 (55), 39 (7).
1-(Tetr a h yd r o-2-p yr a n yloxy)-(9Z,11Z)-h exa d eca d ien e
(21). Compound 21 was prepared from compound 20, as
described before for the preparation of compound 18 from 17,
and in 65% yield: 1H NMR (CDCl3, 400 MHz) δ 6.21 (2H, bd,
J ) 9.5 Hz, H-10 and H-11), 5.40 (2H, bq, J ) 6.6 Hz, H-10
and H-11), 4.54 (1H, t, J ) 2.7 Hz, OCHO), 3.83 (1H, ddd, J )
11.1 Hz, J ) 7.6 Hz, J ) 3.3 Hz, Haxial-5′), 3.69, 3.35 (each 1H,
dt, J ) 9.4 Hz, J ) 7.0 Hz, H-1), 3.43-3.49 (1H, m, Hequat-5′),
2.16-2.10 (2H, m, H-8 or H-13), 1.98-1.91 (2H, m, H-8 or
H-13), 1.83-1.75 (1H, m), 1.71-1.64 (1H, m), 1.59-1.45 (6H,
m), 1.35-1.25 (14H, bs), 0.88 (3H, t, J ) 6.7 Hz, CH3); 13C
NMR (CDCl3, 100 MHz) δ 131.9 (C-9 and C-12), 123.56 (C-10
and C-11), 98.74 (C-1′), 67.59 (C-1), 62.20 (C-5′), 31.76 (C-14),
30.73 (C-3′), 29.71, 29.58, 29.53, 29.38, 29.17, 28.92, 27.40 (C-8
or C-13), 27.13 (C-8 or C-13), 26.19 (C-4′), 25.48 (C-3), 19.63
(C-3′), 13.86 (CH3); EIMS m/z 322 [M]+ (2), 238 (4), 135 (4),
109 (8), 95 (7), 85 (100), 81 (19), 78 (14), 67 (44), 55 (17), 54
(23), 41 (14), 41 (58).
(9Z,11Z)-Hexa d eca d ien -1-ol (22). The compound 21 was
deprotected, in 97% yield, to the alcohol 22 by the method used
to prepare compound 13 from 12: 1H NMR (CDCl3, 400 MHz)
δ 6.22 (2H, bd, J ) 9.8 Hz, H-10 and H-11), 5.41 (2H, bq, J )
7.8 Hz, H-9 and H-12), 3.60 (2H, t, J ) 6.6 Hz, H-1), 2.18-
2.11 (4H, m, H-8 and H-13), 1.65 (1H, bs, OH), 1.52 (2H, quint,
J ) 6.7 Hz, H-2), 1.39-1.28 (14H, bs), 0.88 (3H, t, J ) 6.7 Hz,
H-16); 13C NMR (CDCl3, 100 MHz) δ 132.12 (C-9 or C-12),
131.94 (C-9 or C-12), 123.54 (C-10 or C-11), 123.50 (C-10 or
C-11), 62.95 (C-1), 32.71 (C-2), 31.76 (C-14), 29.56, 29.41, 29.33,
29.16, 27.40 (C-8 or C-13), 27.13 (C-8 or C-13), 25.67 (C-3),
22.30 (C-15), 13.91 (CH3); EIMS m/z 238 [M]+ (28), 136 (6),
121 (16), 110 (12), 109 (15), 108 (14), 107 (6), 98 (9), 96 (9), 95
(32), 94 (21), 93 (22), 91 (9), 85 (10), 83 (7), 82 (49), 81 (50), 80
(19), 79 (28), 69 (21), 68 (16), 67 (100), 66 (9), 57 (11), 55 (34),
54 (28), 53 (9), 44 (9), 42 (28).
(9Z,11Z)-Hexa d eca d ien a l (4). The dienol 22 was oxidized
to the dienal 4 by PDC, as described above for the oxidation
of 13 to compound 1, in an isomeric purity of >99% and
71%yield: 1H NMR (CDCl3, 400 MHz) δ 9.75 (1H, t, J ) 1.85
Hz, CHO), 6.23 (2H, bd, J ) 10.0 Hz, H-10 and H-11), 5.42
(2H, bq, J ) 7.8 Hz, H-9 and H-12), 2.40 (2H, td, J ) 7.32 Hz,
J ) 1.86 Hz, H-2), 2.16 (4H, m, H-8 and H-13), 1.61 (2H, quint,
J ) 7.28 Hz, H-3), 1.40-1.24 (12H, m), 0.88 (3H, t, J ) 7.2
Hz, CH3); 13C NMR (CDCl3, 100 MHz) δ 202.92 (CHO), 132.16
(C-9 or C-12), 131.84 (C-9 or C-12), 123.66 (C-10 or C-11),
123.49 (C-10 or C-11), 43.88 (C-2), 31.78 (C-14), 29.50, 29.17,
29.08, 28.99, 27.37 (C-8 or C-13), 27.16 (C-8 or C-13), 22.32
(C-15), 22.03 (C-3), 13.94 (CH3); EIMS m/z 236 [M]+ (34), 151
(11), 148 (10), 137 (11), 135 (10), 124 (12), 123 (15), 121 (13),
111 (10), 110 (15), 109 (18), 107 (13), 98 (19), 97 (11), 96 (32),
95 (48), 94 (16), 93 (19), 91 (16), 83 (10), 82 (25), 81 (62), 80
(17), 79 (20), 77 (12), 68 (20), 68 (24), 67 (100), 55 (37), 54 (36),
1H, dt, J ) 9.6 Hz, J ) 7.0 Hz, H-1), 3.51-3.46 (1H, m, Hequat
-
5′), 2.15 (2H, q, J ) 7.0 Hz, H-8 or H-13), 2.08 (2H, q, J ) 7.0
Hz, H-8 or H-13), 1.85-1.79 (1H, m), 1.73-1.68 (1H, m), 1.59-
1.52 (6H, m), 1.37-1.29 (14H, m), 0.88 (t, J ) 7.0 Hz, 3H); 13
C
NMR (CDCl3, 100 MHz) δ 134.65 (C-9 or C-12), 130.06 (C-9 or
C-12), 128.57 (C-10 or C-11), 125.58 (C-10 or C-11), 98.83 (C-
1′), 67.68 (C-1), 62.34 (C-5′), 32.55 (C-2′ or C-13), 31.55 (C-2′
or C-13), 30.77 (C-14), 29.73, 29.70, 29.44 (2C), 29.20, 27.68
(C-8), 26.21 (C-4′), 25.49 (C-3), 22.27 (C-15), 19.70 (C-3′), 13.94
(CH3).
(9Z,11E)-Hexa d eca d ien -1-ol (19). The alcohol 19 was
prepared from compound 18 in analogy with compound 13 in
97% yield: 1H NMR (CDCl3, 400 MHz) δ 6.30-6.23 (1H, m,
H-11), 5.92 (1H, t, J ) 10.9 Hz, H-10), 5.63 (1H, dt, J ) 15
Hz, J ) 7.0 Hz, H-12), 5.59-5.23 (1H, m, H-9), 3.60 (2H, t, J
) 6.64 Hz, H-1), 2.13 (2H, q, J ) 7.0 Hz, H-13), 2.07 (2H, q, J
) 7.0 Hz, H-8), 2.02 (1H, bs, OH), 1.57-1.50 (2H, m), 1.30-
1.25 (14H, bs), 0.88 (3H, t, J ) 7.0 Hz, CH3); 13C NMR (CDCl3,
100 MHz) δ 134.62 (C-9 or C-12), 129.96 (C-9 or C-12), 128.57
(C-10 or C-11), 125.54 (C-10 or C-11), 62.96 (C-1), 32.72 (C-2),
32.52 (C-13), 31.51 (C-14), 29.66, 29.42, 29.34, 29.13, 27.61 (C-
8), 25.68 (C-3), 22.23 (C-15), 13.90 (CH3); EIMS m/z 238 [M]+
(38), 135 (14), 121 (10), 110 (13), 109 (13), 108 (8), 107 (10), 96
(18), 95 (26), 94 (42), 93 (21), 91 (37), 85 (20), 81 (20), 80 (42),
79 (35), 67 (100), 55 (42), 54 (36), 43 (56), 31 (63).
(9Z,11E)-Hexa d eca d ien a l (3). The dienal 3 was prepared
from compound 19 as described before for the preparation of
compound 1 (from compound 13) in an isomeric purity of
>99% and 71% yield: 1H NMR (CDCl3, 400 MHz) δ 9.75
(1H, t, J ) 1.81 Hz, CHO), 6.31-6.23 (1H, m, H-11), 5.91 (1H,
t, J ) 11 Hz, H-10), 5.61 (1H, dt, J ) 15.0 Hz, J ) 7.0 Hz,
H-12), 5.6-5.23 (1H, m, H-9), 2.40 (2H, td, J ) 7.0 Hz, J )
1.83 Hz, H-2), 2.1 (2H, q, J ) 7.0, H-13 or H-8), 2.01 (2H, q,
J ) 7.0 Hz, H-8 or H-13), 1.31-1.24 (14H, m), 0.88 (3H, J )
7.0 Hz, CH3); 13C NMR (CDCl3, 100 MHz) δ 202.91 (CHO),
134.6 (C-9 or C-12), 129.95 (C-9 or C-12), 128.6 (C-10 or C-11),
43.88 (C-2), 32.5 (C-13), 31.85 (C-14), 29.5, 29.4, 29.3, 29.1,
27.5 (C-8), 22.27 (C-15), 22.01 (C-3), 13.93 (s. CH3); EIMS m/z
236 [M]+ (38), 121 (10), 95 (16), 94 (7), 93 (7), 91 (10), 83 (10),
82 (16), 81 (25), 80 (8), 79 (16), 77 (9), 68 (7), 67 (36), 66 (6),

Geometric Isomers of 9,11-Hexadecadienal
J ournal of Natural Products, 2002, Vol. 65, No. 6 915
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4357474 A 1982; 98:125738b, 1983.
53 (14), 44 (17), 43 (18), 42 (38), 41 (75); HREIMS m/z
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Ackn owledgm en t. The authors thank International Foun-
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also grateful for scientific advice and assistance by Marie
Bengtsson, at the Department of Plant Protection Sciences,
Swedish University of Agricultural Sciences, Sweden, and by
Alvaro Eiras, ICB/UFMG, Belo Horizonte, Brazil.
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