Synthesis of (Z)-5-decenol and (Z)-5-decenyl acetate, components of the sex pheromones of a variety of lepidoptera

Article abstract of DOI:10.1081/SCC-120018943

Two simple Wittig procedures for the synthesis of (Z)-5-decenol and (Z)-5-decenyl acetate based on the monoacetylation or monobromination of 1,5-pentanediol were followed.

Full text of DOI:10.1081/SCC-120018943

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Synthesis of (Z)-5-Decenol and (Z)-5-Decenyl Acetate,
Components of the Sex Pheromones of a Variety of
Lepidoptera
Amparo Tortajada a , Ramon Mestres a & Martín A. Iglesias-Arteaga b
a Departamento de Quimíca Orgánica, Universitat de Valencia, Edificio de Investigación,
Valencia, Spain
b Departamento de Química, Centro de Investigación y Estudios Avanzados del Instituto
Nacional Politécnico, México D.F., México
Version of record first published: 17 Aug 2006.
To cite this article: Amparo Tortajada , Ramon Mestres & Martín A. Iglesias-Arteaga (2003): Synthesis of (Z)-5-Decenol and
(Z)-5-Decenyl Acetate, Components of the Sex Pheromones of a Variety of Lepidoptera, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 33:10, 1809-1814
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SYNTHETIC COMMUNICATIONSÕ
Vol. 33, No. 10, pp. 1809–1814, 2003
Synthesis of (Z )-5-Decenol and
(Z )-5-Decenyl Acetate, Components of the
Sex Pheromones of a Variety of Lepidoptera
Amparo Tortajada,1 Ramon Mestres,1 and
Martın A. Iglesias-Arteaga2,
*
1Departamento de Quimıca Organica,
Universitat de Valencia, Edificio de Investigacion,
Valencia, Spain
2Departamento de Quımica, Centro de Investigacion y
Estudios Avanzados del Instituto Nacional Politecnico,
Mexico D.F., Mexico
ABSTRACT
Two simple Wittig procedures for the synthesis of (Z)-5-decenol and
(Z )-5-decenyl acetate based on the monoacetylation or monobromi-
nation of 1,5-pentanediol were followed.
Key Words: Pheromones; Lepidoptera; Wittig reaction.
*Correspondence: Martın A.Iglesias-Arteaga,DepartamentodeQuımica,Centro
de Investigacion y Estudios Avanzados del Instituto Nacional Politecnico,
Apartado Postal 14-740, 07000 Mexico D.F., Mexico; Fax: 52 55 57477132;
E-mail: iglesias@relaq.mx.
1809
DOI: 10.1081/SCC-120018943
Copyright & 2003 by Marcel Dekker, Inc.
0039-7911 (Print); 1532-2432 (Online)
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1810
Tortajada, Mestres, and Iglesias-Arteaga
INTRODUCTION
Sex pheromones of Lepidoptera are usually long chain aldehydes,
alcohols or esters with one or more double bonds. The presence of the
same compound in the sex pheromones of several insects is a common
fact.[1] Symmetrical diols are suitable starting material for both the acety-
lenic[2] or the Wittig[3] routes, which are the most common approaches
employed to prepare sex pheromones of Lepidoptera. Both ways usually
include monofunctionalization or monoprotection of the symmetrical
diol. We now wish to report on the application of simple monoacetylation
or monobromination procedures to the Wittig synthesis of (Z)-5-decenol
and (Z )-5-decenyl acetate, which are constituents of the sex attractant
mixtures of 22 and 69 insects, respectively.
RESULTS AND DISCUSSION
Treatment of 1,5-pentanediol 1 with NaH in dry THF produced the
alkoxyde which on reaction with acetic anhydride led to the monoacetate
2 in 64% after flash chromatography, (See Sch. 1). Oxidation with PCC
in CHCl3 produced the aldehyde 3, which on Wittig olefination with
pentyltriphenylphosphonium bromide in THF/DMSO/NaH led to the
(Z)-5-decenyl acetate 4. The isomeric purity was verified using GC
(T ¼ 170ꢀC) Retention Time ¼ 9.66 min. Addition of THF to the solution
of the anion of DMSO (Naþ–CH2(SO)CH3) prior to the addition of
phosphonium salt allows the reduction of the amount of dry DMSO,
which is usually much more higher than the required for the produc-
tion of the stoichimetric amount of the base which deprotonates the
phosphonium salt. This has allowed us to scale the Wittig procedure
up to a 10 mmol amount without significant increases in the volumes of
DMSO. Saponification of the alkenol acetate 4 led to the alkenol 5.
Scheme 1.

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Synthesis of (Z)-5-Decenol And (Z)-5-Decenyl Acetate
1811
Scheme 2.
The second synthetic pathway included monobromination of
1,5-pentanediol with HBr in refluxing benzene under water removal
conditions, followed by formation of the o-functionalized phosponium
salt which was treated with the THF solution of two equivalents of
(Naþ–CH2(SO)CH3) and one equivalent of pentanal to produce (Z)-5-
decenol 5 in moderate yield. Acetylation of the alkenol 5 produced (Z)-5-
decenyl acetate 4, (See Sch. 2).
EXPERIMENTAL
IR spectra were recorded on a BIORAD FTS-7 spectrometer. NMR
spectra were recorded on a Varian VXR 400 MHz spectrometer using
CDCl3 as solventwiht TMS ( 1H) as references. Gas Chromatograms
were recorded on a KNK-300-HRGC KONIC chromatograph using a
capillary column DB-5(Long 30 m, Internal Diameter 0.25 mm, Film
0.25 nm Temperature limit 60ꢀC to 325ꢀC, split1/30).
1,5-Pentanediol monoacetate 2: NaH (120 mg, 5 mmol) was added to
a solution of 1,5 pentanediol 1 (521 mg, 5.0 mmol) in dry THF (30 mL).
The suspension was refluxed and stirred under argon for 5 h, a solution
of acetic anhydride (510 mg, 5.0 mmol) in dry hexane (5 mL) was added
dropwise and the mixture was stirred for 3 h, followed by carefully
addition of water and extraction with ethyl acetate (50 mL). The organic
layer was washed with 5% Na2CO3 (2 ꢁ 25 mL) and brine (2 ꢁ 25 mL),
dried (MgSO4) and the solvent evaporated. The residue was purified
by flash chromatography (hexane/ethyl acetate, 3/2) to afford the
monoacetate
Elemental analysis: Estimated for C7H14O3: C, 57.51%; H, 9.65%.
2 (395 mg, 2.7 mmol, 54%) as a colorless liquid.
Found: C, 57.60%; H 9.72%. IR (cmꢂ1): 3422 (ꢀOH); 2939, 2867
1
(ꢀCsp3–H); 1739 (ꢀC¼O); 1241, 1036 (ꢀC–O). H NMR (ꢁ, ppm): 3.96

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Tortajada, Mestres, and Iglesias-Arteaga
(2H, t, J ¼ 6.6 Hz, CH2OAc); 3.5 (2H, t, J ¼ 6.6 Hz, CH2OH); 1.94 (3H,
s, CH3COO); 1.5 (6H, m, (CH2)3).
5-Acetoxypentanal 3: PCC (1.044 g, 4.8 mmol) was added to a
solution of 1,5-pentanediol monoacetate 2 (472 mg, 3.2 mmol) in
CHCl3 (25 mL) and the mixture was stirred for 4 h. The reaction mixture
filtered through a chromatographic column packed with silica gel (10 g)
(eluted with hexane/ethyl acetate, 3/2.) and the solvent evaporated to
afford pure 5-acetoxypentanal 3 (439 mg, 3.0 mmol, 94%) as a colorless
liquid. Elemental analysis: Estimated for C7H12O3: C, 58.32%; H, 8.39%.
Found: C, 58.11%; H, 8.48%. IR (cmꢂ1): 2959 (ꢀCsp3–H); 1741 (ꢀC¼O
carboxyl); 1710 (ꢀC¼O carbonyl) 1245, 1044 (ꢀC–O). 1H NMR (ꢁ, ppm):
9.76 (1H, t, J ¼ 1.7 Hz, CHO); 4.03 (2H, t, J ¼ 6.6 Hz, CH2OAc); 2.35
(2H, t, J ¼ 6.9 Hz, CH2CHO); 2.01 (3H, s, CH3COO); 1.64 (6H, m, (CH2)3).
(Z )-5-Decenyl acetate 4: NaH (80 mg, 3.3 mmol, 1.1 equiv.) was
added to dry DMSO (5 mL). The mixture was stirred under argon at
60ꢀC until total dissolution of NaH, dry THF (15 mL) was added and
the mixture cooled to 10ꢀC. Pentyltriphenylphoshonium bromide
(438 mg, 3.3 mmol, 1.1 equiv.) was added under vigorous stirring and
the temperature was allowed to rise to 25ꢀC. After a brilliant red
colour developed the mixture was cooled to 0ꢀC and a solution of 5-acet-
oxypentanal 3 (438 mg, 3.0 mmol, 1 eq.) in dry THF (10 mL) was added.
Stirring was continued for 24 h. The resulting suspension was poured into
saturated NaCl solution (50 mL), filtered and extracted with diethyl ether
(2 ꢁ 30 mL). The combined extracts were washed with brine (2 ꢁ 25 mL),
dried (MgSO4), evaporated and the resulting residue was purified by flash
chromatography (hexane/ethyl acetate, 9/1) in silica gel to afford (Z)-5-
decenyl acetate 4 (389 mg, 1.9 mmol, 65%) as a pale yellow liquid.
Elemental analysis: Estimated for C12H22O2: C, 72.68%; H, 11.18%.
Found: C, 72.49%; H, 11.27%. IR (cmꢂ1): 3005 (ꢀCsp2–H); 2957, 2860
1
(ꢀCsp3–H); 1742 (ꢀC¼O); 1240, 1040 (ꢀC–O). H NMR (ꢁ, ppm): 5.33
(2H, dt, J1 ¼ 6 Hz, J2 ¼ 2.1 Hz CH¼CH); 4.03 (2H, t, J ¼ 6.6 Hz,
CH2OAc); 2.00 (7H, m, CH2CH¼CHCH2, CH3COO); 1.3 (2H, m,
CH2); 1.3 (6H, m, (CH2)2); 0.9 (3H, m, CH3).
(Z )-5-Decenol 5: KOH (112 mg, 2 mmol) was added to a solution of
(Z )-5-decenyl acetate 4 (157 mg, 0.79 mmol) in methanol (5 mL), the
mixture was stirred for 24 h, NaCl saturated solution (2 mL) was added
and methanol was eliminated under reduced pressure. The residue was
extracted with ethyl acetate (40 mL) and the organic layer washed with
3% HCl solution (2 ꢁ 15 mL) and brine (2 ꢁ 15 mL), dried (MgSO4) and
evaporated to afford pure (Z )-5-decenol 5 (119 mg, 0.77 mmol, 93%) after
flash chromatographic purification (hexane/ethyl acetate, 9/1). Elemental
analysis: Estimated for C10H20O: C, 76.86%; H, 12.90%. Found: C,

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Synthesis of (Z)-5-Decenol And (Z)-5-Decenyl Acetate
1813
76.73%; H, 12.99%. IR (cmꢂ1): 3332 (ꢀOH); 3004 (ꢀCsp2–H); 2932, 2859
(ꢀCsp3–H); 1065 (ꢀC–O). 1H NMR (ꢁ, ppm): 7.25 (1H, s, OH); 5.36 (2H, t,
J ¼ 4.35 Hz,
CH¼CH);
3.65
(2H,
t,
J ¼ 6.3Hz,
CH2OH); 2.00 (4H, m, CH2CH¼CHCH2); 1.6 (2H, m, CH2); 1.4 (6H, m,
(CH2)2); 0.9 (3H, m, CH3).
5-Bromopentanol 6: A mixture of 1,5-pentanediol 1, (10.451 g,
100 mmol) 48% HBr (12.5 mL) and benzene (200 mL) was stirred and
refluxed for 24 h under a Dean Stark trap, the resulting solution was
washed with 6 N NaOH solution (2 ꢁ 30 mL), 5% HCl (2 ꢁ 30 mL),
water (2 ꢁ 30 mL) and brine (2 ꢁ 30 mL). The organic layer was dried
(MgSO4) and evaporated to afford pure 5-bromopentanol 6 (10.986 g,
65.7 mmol, 66%) as a pale yellow liquid. Elemental analysis: Estimated
for C5H11BrO: C, 35.95%; H, 6.64%. Found: C, 35.89%; H, 6.69%. IR
(cmꢂ1): 3284 (ꢀOH); 2942, 2810 (ꢀCsp3–H); 1044 (ꢀC–O); 562 (ꢀC–Br).
1H NMR (ꢁ, ppm): 3.71 (1H, s, OH); 3.64 (2H, t; J ¼ 6.3 Hz, CH2Br); 3.4
(4H, dt, J1¼2.1 Hz, J2¼6.9 Hz, CH2OH); 1.9 (2H, q, J ¼ 7.2 Hz,
CH2CH2Br); 1.5 (4H, m, (CH2)2)
(Z )-5-Decenol 5: A. Preparation of 5-hydroxypentyltriphenylphosho-
nium bromide: 5-bromopentanol (335 mg, 2 mmol) 6 and triphenylphos-
pine (525 mg, 2 mmol) were refluxed for 48 h in ethyl acetate (20 mL), the
solvent was evaporated, the resulting gummy solid was refluxed in ben-
zene for 2 h, the hot liquid was decanted, dry THF (20 mL) was added
and the solution was maintained under strong stirring for 3 h. B. Wittig
olefination: NaH (106 mg, 4.4 mmol, 2.2 equiv.) was added to dry DMSO
(5 mL), the mixture was stirred under argon at 60ꢀC until total dissolu-
tion of NaH, dry THF (15 mL) was added, the mixture cooled to 15ꢀC
and added under strong stirring to a cooled (15ꢀC) THF slurry of the
phosphoniom saltprepared above. After a brilliantred colour developed
the mixture was cooled to 0ꢀC, a solution of pentanal (172 mg, 2 mmol,
1 equiv.) in dry THF (10 mL) was added and stirring was maintained for
24 h. The resulting suspension was poured into saturated NaCl solution
(50 mL), filtered and extracted with diethyl ether (2 ꢁ 30 mL). The com-
bined extracts were washed with brine (2 ꢁ 25 mL) dried (MgSO4), eva-
porated and the resulting residue purified by flash chromatography
(hexane/ethyl acetate, 9/1) in silica gel to afford (Z)-5-decenol 4
(164 mg, 1.1 mmol 52%) identical as described above.
(Z )-5-Decenyl acetate 4: Acetic anhydride (102 mg, 1 mmol, 2 equiv.)
was added to a solution of (Z)-5-decenol 5 (78 mg, 0.50 mmol) in dry
pyridine (2 mL) and the mixture was stirred overnight. Ice water (5 mL)
was added, the solution was stirred for 30 min, ethyl acetate (20 mL) was
added and the mixture was washed with water (2 ꢁ 10 mL) 10% solution
of CuSO4 (3 ꢁ 10 mL) and water (3 ꢁ 15 mL). The dried solvent(MgSO 4)

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1814
Tortajada, Mestres, and Iglesias-Arteaga
was evaporated to afford (Z)-5-decenyl acetate 4 (96 mg, 0.49 mmol,
98%) identical as described above.
CONCLUSION
A simple procedure based on the monoacetylation of 1,5-pentanediol
was followed for the synthesis of (Z)-5-decenol and (Z)-5-decenyl acetate.
Experiments to improve yields of monoacetylation and to adapt this
procedure to longer chain symmetrical diols are on development.
Additionally a procedure to obtain the same products based on the
preparation of o-functionalized phosponium salt was developed.
ACKNOWLEDGMENTS
Thanks are due to Mrs. Rosa Arteaga and to Dr. Jose L. Mola
Garate for correction of the manuscript. One of the authors, M.A.I.A.,
´
wants to acknowledge Vicerrectorado de Investigacion of the University
of Valencia for a Visiting Grant as Invited Professor, and the people
´
of laboratories 4.27 and 4.34 of Edificio de Investigacion for their kind
supportand friendship.
REFERENCES
1. Arn, H.; Toth, M.; Priesner, E. A List of Sex Pheromones of
Lepidoptera and Related Attractants, 2nd Ed.; International Organiza-
tion for Biological Control: Monfavet, 1992; Online version available
@http://www.nysaes.cornell.edu/fst/faculty/acree/pheronet
2. Mori, K. In The Total Synthesis of Natural Products; ApSimon, J.,
Ed.; John Wiley: New York, 1981; Vol. 4. and references therein.
3. Bestmann, H.J.; Vostrowky, O. Synthesis of pheromones by stereo-
selective carbonyl olefination: a unitesed construction principal.
Chem. Phys. Lipid. 1979, 24, 335–389.
Received in the USA August 16, 2002