Syntheses of female sex pheromone precursors of pine sawfly species and of some structurally related methyl-branched long-chain 2-alkanols.

Article abstract of DOI:10.1023/A:1016289902732

3,7-Dimethyl-2-undecanol, 3,7,9-trimethyl-2-tridecanol, and 3,7, 11-trimethyl-2-tridecanol were synthesized as racemic mixtures in moderate yields. The alcohols are known precursors of the female sex pheromones of the pine sawfly species Diprion nipponica, Macrodiprion nemoralis, and Microdiprion pallipes, respectively. Stereoisomeric mixtures of 3,8,12-trimethyl-2-tridecanol, erythro-(2R,3R, 11R/S)-3,11-dimethyl-2-tetradecanol, 3,5-dimethyl-2-tetradecanol, and 5,7-dimethyl-2-tetradecanol, structurally related to sex pheromone alcohol precursors of pine sawfly species, were also synthesized in moderate yields. The key reaction in the syntheses was the ring opening of gamma-butyrolactones by using different alkyl lithiums as nucleophiles.

Full text of DOI:10.1023/A:1016289902732

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Journal of Chemical Ecology, Vol. 28, No. 6, June 2002 ( 2002)
SYNTHESES OF FEMALE SEX PHEROMONE PRECURSORS
OF PINE SAWFLY SPECIES AND OF SOME
STRUCTURALLY RELATED METHYL-BRANCHED
LONG-CHAIN 2-ALKANOLS
¨
ERIK HEDENSTROM and FREDRIK ANDERSSON
Chemistry, Department of Natural and Environmental Sciences
Mid Sweden University
SE-851 70 Sundsvall, Sweden
(Received October 10, 2001; accepted February 9, 2002)
Abstract—3,7-Dimethyl-2-undecanol, 3,7,9-trimethyl-2-tridecanol, and 3,7,
11-trimethyl-2-tridecanol were synthesized as racemic mixtures in moderate
yields. The alcohols are known precursors of the female sex pheromones of the
pine sawfly species Diprion nipponica, Macrodiprion nemoralis, and Microdi-
prion pallipes, respectively. Stereoisomeric mixtures of 3,8,12-trimethyl-2-
tridecanol, erythro-(2R,3R,11R/S)-3,11-dimethyl-2-tetradecanol, 3,5-dimethyl-
2-tetradecanol, and 5,7-dimethyl-2-tetradecanol, structurally related to sex
pheromone alcohol precursors of pine sawfly species, were also synthesized
in moderate yields. The key reaction in the syntheses was the ring opening of
-butyrolactones by using different alkyl lithiums as nucleophiles.
Key Words—Sex pheromone, pine sawfly, synthesis, Diprion nipponica,
Macrodiprion nemoralis, Microdiprion pallipes.
INTRODUCTION
We have long been interested in the sex pheromones of pine sawflies, and our
work has thus far included identification, syntheses, and biological activities of
such chemical substances (for recent examples see Bergstro¨m et al., 1998; Karlsson
and Hedenstro¨m, 1999; Larsson et al., 2001; Wassgren et al., 2000). In the northern
hemisphere, some pine sawfly species are severe pests on pines (Smith, 1993). Con-
sequently, our interest is to monitor and to control pine sawfly populations by using
mass trapping or mating disruption techniques (for two recent examples see Rieske
To whom correspondence should be addressed. E-mail: erik.hedenstrom@mh.se
1237
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0098-0331/02/0600-1237/0 2002 Plenum Publishing Corporation

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HEDENSTROM AND ANDERSSON
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FIG. 1. The sex pheromone precursor alcohols 1–5 identified so far in females of pine
sawfly species. The syntheses of compounds 3–5 as stereoisomeric mixtures are presented
in this paper.
et al., 2001; Martini et al., 2002). Several structurally similar sex pheromone pre-
cursor alcohols have been identified in females of pine sawfly species (Anderbrant,
1993; Bergstro¨m et al., 1995, 1998; Tai et al., 1998; Wassgren et al., 2000; Larsson
et al., 2001). As sex pheromone, most of the pine sawfly species employ es-
ters of erythro-(2S,3S,7S)- or threo-(2S,3R,7R)-3,7-dimethyl-2-pentadecanol (1,
diprionol, Figure 1). From virgin female extracts of the pine sawfly Neodiprion
sertifer, only the precursor alcohol 1 has been isolated and no trace of the behav-
ioral active ester was found (Wassgren et al., 1992). So far, little is known about the
pheromone biosynthesis in pine sawfly species, and no production site has been
found for the pheromone or the precursor alcohol. The alcohol 1 has been found
in different parts of the female N. sertifer (Wassgren et al., 1992) and probably is
stored and then esterified just before emission, as suggested earlier (Jewett et al.,
1976).
The sex pheromone precursors identified in female pine sawfly species are
basically methyl-branched long-chained 2-alcohols that may be divided into two
structural groups. One group is based on different lengths of the carbon chain,

PINE SAWFLY PHEROMONE PRECURSORS
1239
FIG. 2. Lower and higher homologs identified in females of pine sawflies N. sertifer (6 and
7) and D. pini (6–8) together with the species specific sex pheromone precursor, alcohols 1
and 2, respectively.
with methyl branching on carbons 3 and 7 (3,7-dimethyl-2-pentadecanol (1); 3,7-
dimethyl-2-tridecanol (2); and 3,7-dimethyl-2-undecanol (3); Figure 1). From fe-
male extracts of the pine sawflies N. sertifer (Hedenstro¨m et al., 1992; Wassgren
et al., 1992) and Diprion pini (Bergstro¨m et al., 1995), some minor (1–5%)
pheromone components were identified (3,7-dimethyl-2-hexadecanol (6); 3,7-
dimethyl-2-tetradecanol (7); and 3,7-dimethyl-2-dodecanol (8); Figure 2). These
minor compounds gave a GC-EAD response but showed no activity in field tests
performed with either pine sawfly species (Wassgren et al., 1992; Bergstro¨m et al.,
1995). The other structural group is based on the same 13-carbon chain length but
includes yet another methyl branching on a carbon different from carbons 3 and
7, i.e., on carbon 9 or 11 (3,7,11-trimethyl-2-tridecanol, (4); and 3,7,9-trimethyl-
2-tridecanol (5); Figure 1). The propionate of 3,7,11-trimethyl-2-tridecanol (4),
and the acetate of 3,7,9-trimethyl-2-tridecanol (5), have been found to be the sex
pheromones of Microdiprion pallipes (Bergstro¨m et al., 1998; Nakamura and
Mori, 1999; Larsson et al., 2001) and Macrodiprion nemoralis (Karlsson and
Hedenstro¨m, 1999; Wassgren et al., 2000), respectively.
To confirm the structure of future pheromone candidates that likely will be
found in other pine sawfly species, we need access to an extensive library of
structurally related compounds for screening their mass spectra and gas chro-
matography (GC) retention times and relating the observed variation to the dif-
ferences in structure. As part of this work, we previously synthesized some struc-
tural analogs of diprionol, representing a third group of compounds with one
methyl group missing [(2S,3S)-3-methyl-2-pentadecanol (9); (2S,7S)-7-methyl-
2-pentadecanol (10); and (2S,6S)-2,6-dimethyl-1-tetradecanol (11); Figure 3]
(Hedenstro¨m et al., 1992). The biological activity of the acetates of compounds
9–11 have been tested on the pine sawfly N. sertifer in Sweden (Anderbrant et al.,

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HEDENSTROM AND ANDERSSON
1240
FIG. 3. The acetates of stereoisomeric pure diprionol analogues 9–11. In a field study
performed in Sweden on the pine sawfly N. sertifer, no biological activity was found.
in personal communication). None of the analogous acetates showed any activity
in the field. In field experiments performed in Japan on the same species (Tai et al.,
1992), both the erythro-(2S,3S) and the threo-(2S,3R) isomers of analog 9 were
active.
We present in this paper the syntheses of some novel substances. One com-
pound, 3,8,12-trimethyl-2-tridecanol (12); (Figure 4), which is structurally related
to compounds 4 and 5 (Figure 1), and three others represent a new, fourth group of
compounds that are structurally related to sex pheromones of pine sawflies. This
group has the same 14-carbon chain length but a variation in the attachment of the
two methyl groups [erythro-(2R,3R,11R/S)-3,11-dimethyl-2-tetradecanol (13);
3,5-dimethyl-2-tetradecanol (14); and 5,7-dimethyl-2-tetradecanol (15), Figure 4].
Wealsopresentherethesynthesesofthe16stereoisomericmixturesof3,7,11-
and 3,7,9-trimethyl-2-tridecanol, compounds 4 and 5, respectively, by somewhat
FIG. 4. Stereoisomeric mixtures of methyl-branched, long-chained alcohols 12–15 that are
structurally related to sex pheromone precursors in pine sawfly species. Their syntheses are
presented in this paper.

PINE SAWFLY PHEROMONE PRECURSORS
1241
different procedures from those previously published (Karlsson and Hedenstro¨m,
1999; Larsson et al., 2001). The synthesis of 3,7-dimethyl-2-undecanol (3) as an
eight stereoisomeric mixture is also presented. The propionate of this compound
wasrecentlyidentifiedasthesexpheromoneofDiprionnipponica(Taietal., 1998).
METHODS AND MATERIALS
General Chemical Procedures and Instruments
Unless otherwise stated, commercially available chemicals were used. 2-
Methyl-1-pentanol (17g), 3,7-dimethyl-1-octanol (17f), -butyrolactone (20), and
4-methyl- -butyrolactone (21) were purchased from Aldrich and distilled prior to
use. 3,4-Dimethyl- -butyrolactone (19) was prepared according to Hedenstro¨m
et al. (1992). The trans–cis ratio was 65:35 according to GC [iso 115 C, reten-
tion time: cis (minor): 4.15 min; trans (major): 5.34 min]. The analytical and
spectral data were identical to those reported in Hedenstro¨m et al. (1992). Dry
acetone (Na2CO3), diethyl ether (LiAlH4), diethyleneglycole (NaOH), pyridine
(CaH2), and THF (K and benzophenone) were distilled from the indicated dry-
ing agents. Reactions sensitive to moisture and/or oxygen were carried out un-
der argon. Preparative liquid chromatography was performed on straight-phase
silica gel (Merck 60, 230–400 mesh, 0.040–0.063 mm, 10–50 g/g of product
mixture) by using a gradient elution technique with an increasing concentration
of distilled ethyl acetate in distilled cyclohexane or of distilled diethyl ether in
distilled pentane. Thin-layer chromatography (TLC) was performed to monitor
the progress of the reactions on silica gel plates (Merck 60, precoated aluminum
foil), using ethyl acetate (20 or 40%) in hexane as an eluant, and plates were
developed by means of ultraviolet irradiation and/or by spraying with vanillin in
sulfuric acid and heating at 120 C. Unless otherwise stated, GC analyses were
carried out by using a capillary column [J & W DB-Wax, 30 m 0.32 mm ID,
d f = 0.25 m, carrier gas He (103 kPa), split ratio 1:30]. Mass spectral anal-
yses were carried out on a Saturn 2000 GC/MS/MS instrument, coupled to a
Varian 3800 GC instrument, using a capillary column [VA-5MS, 30 m 0.32 mm
ID, d f = 0.25 m, carrier gas He (60 kPa), split ratio 1:20]. Boiling points are
uncorrected and are, unless otherwise stated, given as air bath temperatures (bath
temperature/millimeters if mercury) in a bulb-to-bulb apparatus (Bu¨chi GKR-51).
IR spectra were recorded as concentrated substance between NaCl or KBr plates
with a Perkin Elmer 782 or Perkin Elmer 16PC FT-IR spectrometer. NMR spectra
were recorded in CDCl3 with tetramethylsilane as an internal standard using either
a Jeol EX270 (270 MHz 1H and 67.8 MHz 13C) or a Bruker DMX 250 (250 MHz
1H and 62.9 MHz 13C) instrument. Optical rotation was measured on a Perkin
Elmer 241 polarimeter using a 1-dm cell. Elemental analyses were performed by
Mikro Kemi AB, Uppsala, Sweden.

¨
HEDENSTROM AND ANDERSSON
1242
SCHEME 1. a) 1) Na(s), EtOH, 1x 2) butylbromide, heptylbromide or 1-bromo-2-
methylhexane, 1x 3) KOH, EtOH/H2O, 1x 4) 1x; b) LiAlH4, Et2O; c) Br2, PPh3, CH2Cl2,
0 C 4 hr; d) I2, PPh3, imidazole, 0 C, 2 hr.
Synthesis of 3,7-Dimethyl-2-Undecanol (3)
2-Methylhexanoic Acid (16a) (Scheme 1). The compound was prepared by
malonic ester synthesis using the method in Karrer et al. (1930) but from 1-
bromobutane. The acid obtained was pure as judged by GC. Bp 120–122 C/
14 mm Hg [bp 109–110 C/17 mm Hg for (S)-2-methylhexanoic acid (Terashima
et al., 1979)]. n2D0 = 1.4249 0.0002 [n2D0 = 1.4195 (Lide, 1999)]. IR data were
1
similar to data for (S)-2-methylhexanoic acid (Terashima et al., 1979). The H
NMR spectral data were identical to those reported in the literature (Lubell et al.,
1990) for (R)-2-methylhexanoic acid.
2-Methyl-1-Hexanol (17a) (Scheme 1). This compound was obtained from
the above prepared 2-methylhexanoic acid (16a) via LiAlH4 reduction (Edlund
et al., 1996). It was obtained (16 g, 0.137 mol, 94%) in a >99.5% purity, as judged
by GC. Bp 164–165 C/760 mm Hg [bp 112–113.5 C/100 mm Hg (Wender et al.,
1950)]. n2D0 was identical to that reported in the literature (Mori and Horikiri, 1996)
for (R)-2-methyl-1-hexanol. IR and 1H NMR spectral data were identical to those
reported in the literature (Decicco and Grover, 1996) for (S)-2-methyl-1-hexanol.
1-Bromo-2-Methylhexane (18a) (Scheme 1). This was prepared as described
below for 1-bromo-2-methylnonane (18b) but from 2-methyl-1-hexanol (17a).
Distillation {bp 72 C/10.6 mm Hg [bp 90–92 C/40 mm Hg (Manabe et al., 1985)]}
gave the pure product as judged by GC (19.3 g, 0.108 mol, 80%). n2D0 = 1.4509
0.0002 [n2D5 = 1.4460 (Manabe et al., 1985)]. IR and 1H NMR data were similar
to data in Kurosawa et al. (1997) for (2S)-1-bromo-2-methylhexane.
3,7-Dimethyl-2-Undecanol (3) (Scheme 2). A mixture of stereoisomers was
prepared with the preparative procedure used for 3,7-dimethyl-2-dodecanol
(Bergstro¨m et al., 1995) with slight modification. 3,4-Dimethyl- -butyrolactone
(19), (trans–cis 65:35) and 1-bromo-2-methylhexane (18a) were used as starting
materials, and before adding the bromide to 3.5 equivalents of lithium in Et2O, the
oxide on the surface of the metal was removed with one equivalent of t-butanol at
10 C, theEt2Owasremoved, andthemetalwaswashedtwicewithdryEt2O. There-
after, we followed the method described in Bergstro¨m et al. (1995). The compound
was obtained in a 30% yield, and the threo–erythro ratio was 65:35 as analyzed

PINE SAWFLY PHEROMONE PRECURSORS
1243
SCHEME 2. a) Li(s), Et2O, 10 C, 2 hr; b) t-Bu-Li, n-pentane/Et2O, 78 C, 1 hr; c) 1)
Add to the lactone in Et2O at 78 C, 4 hr; 2) H20; d) (NH2)2, KOH, diethyleneglycol,
180 C, 1 hr, 220 C, 2 hr; e) 1) CH2PPh3, benzene, ambient temp., 16 hr; 2) H2O; f) Pd/C,
H2, MeOH, ambient temp., 72 hr.
by GC [iso 140 C, retention times for the propionate: threo (2S,3R and 2R,3S,
minor): 8.30 min; erythro (2S,3S and 2R,3R, major): 8.61 min]. Bp 98 C/0.68
mm Hg. n2D0 = 1.4451 0.0002. IR (neat): 3355, 2959, 2924, 2858, 1464, 1378,
1
1094, 1002, 924, 889, 728, 665 cm 1. H NMR and MS data were similar to
published data (Tai et al., 1998) for (2S,3R,7R/S)-3,7-dimethyl-2-decanol. 13C
NMR (62.9 MHz) : 14.13, 14.17, 14.49, 14.52, 19.28, 19.33, 19.62, 19.75, 20.27,
20.28, 23.02, 24.63, 24.66, 24.72, 24.75, 29.30, 29.33, 32.67, 32.68, 32.71, 32.77,
32.88, 32.97, 36.66, 36.84, 37.28, 37.37, 39.76, 39.79, 40.01, 40.04, 71.36, 71.45,
71.74, 71.80 ppm. Anal. calcd for C13H28O: C 77.9%, H 14.1%; found: C 77.9%, H
14.2%.
Synthesis of 3,7,11-Trimethyl-2-Tridecanol (4)
2,6-Dimethyl-1-Octanol (17e) (Scheme 3). The 2,6-dimethyloct-2-ene-1-
tossylate was prepared similar to Bergstro¨m et al. (1998), but starting from cit-
ronellol. The tossylate was obtained in quantitative yield, the purity was checked
1
by IR and H NMR, and it was used without further purification. The tossylate
(19.1 g, 61.5 mmol) in dry Et2O (110 ml) was added dropwise to LiAlH4 (2.60 g,
68.5 mmol) in dry Et2O (50 ml) at ambient temperature. The reaction was heated to
reflux for 3.5 hr (no starting material remained according to TLC), cooled to 0 C,
and quenched with water (2.6 ml) and 15% aqueous NaOH (2.6 ml) followed by
SCHEME 3. a) TsCl, pyridine, 5 C, 4 hr; b) 1) LiAlH4, Et2O, 1x 3.5 hr; 2) H2O; c) 1)
SeO2, EtOH 2) NaBH4, EtOH, 2 hr; d) RaNi, H2, MeOH/H2O, 72 hr.

¨
HEDENSTROM AND ANDERSSON
1244
H2O (2.6 ml). After refluxing for 1 hr, the precipitate was filtered, and the solution
was dried (MgSO4). The Et2O was distilled off through a column, and the residual
oil was chromatographed (eluted with pentane and distilled off through a column)
and distilled to give 6.47 g (46.2 mmol, 75%) of the pure alkene (>99% as judged
by GC). Bp, n2D0, IR and 1H NMR spectral data were identical to those reported by
Mori and Harashima (1993) for (6R)-2,6-dimethyl-2-octen. 13C NMR data were
similar to those of Naoshima et al. (1988) for (6S)-2,6-dimethyl-2-octen]. MS (EI)
data were similar to Rossi and Salvadori (1979) for (6R)-2,6-dimethyl-2-octen.
The alkene (2.06 g, 14.7 mmol) was added to a solution of SeO2 (1.23 g,
11.1 mmol) in EtOH (210 ml) and refluxed. A mixture of the allylic alcohol and the
, -unsaturated aldehyde was formed and after 30 hr, MeOH was added and the se-
lenium residues removed by filtration. Evaporation of the solvent was followed by
extraction with Et2O (3 50 ml). The combined organic phases were washed with
aqueous saturated Na2CO3 and dried (MgSO4). Liquid chromatography and re-
moval of solvent yielded a mixture of the allylic alcohol and the , -unsaturated
aldehyde (1.17 g, 7.58 mmol, 52%). This was dissolved in absolute EtOH (30 ml)
and added drop by drop to a suspension of NaBH4 (0.41 g, 10.7 mmol) in EtOH
(80ml)at5 C. After3.5hr, TLCindicatednoaldehyde, andH2O(115ml)andbrine
(50 ml) were added. Extraction with Et2O (3 100 ml) and drying (MgSO4) of
the combined extracts gave after liquid chromatography and distillation {bp 70 C/
3 mm Hg [bp 100–103 C/10 torr (Webb, 1961)]} 0.99 g (6.33 mmol, 84%) of the
unsaturated pure alcohol. nD20 = 1.4590 0.0002 [n2D2 = 1.4541 for (E)-(6R)-2,6
dimethyl-2-octen-1-ol (Mori and Harashima, 1993)]. IR data were similar to Mori
and Harashima (1993) for (E)-(6R)-2,6-dimethyl-2-octen-1-ol. 1H NMR and MS
(EI) spectral data were identical to those of Ghisalberti et al. (1991) for (6R)-2,6-
dimethyl-2-octen-1-ol. Compound 17e was obtained as a mixture of isomers by
RaNi reduction of 2,6-dimethyl-2-octen-1-ol according to Ho¨gberg et al. (1992).
Bp 90 C/6.8 mm Hg [bp 60 C/1 mm Hg for (2R,6R)-2,6-dimethyl-1-octanol
(Cheskis et al., 1988)]. n2D0 = 1.4249 0.0002 [n2D0 = 1.4371 for (2R,6R)-2,6-
1
Dimethyl-1-octanol (Cheskis et al., 1988)]. The IR and H NMR spectral data
were identical to those reported by Cheˆnevert and Desjardins (1996) for (2R,6R)-
2,6-dimethyl-1-octanol.
1-Bromo-2,6-Dimethyloctane (18e) (Scheme 1). This was prepared as be-
low for 1-bromo-2-methylnonane (18b) but from 2,6-dimethyl-1-octanol (17e).
Distillation {bp 70–72 C/8 mm Hg [bp 45 C/0.7 mm Hg for (2R,6R)-1-bromo-
2,6-dimethyloctane (Cheskis et al.,1988)]} gave the pure product, as judged by GC.
n2D0 = 1.4530 0.0002 [n2D0 = 1.4565 for (2R,6R)-1-bromo-2,6-dimethyloctane
(Cheskisetal., 1988)]. TheIR, 1HNMR, andMS(EI)spectraldatawereidenticalto
those reported by Cheskis et al. (1988) for (2R,6R)-1-bromo-2,6-dimethyloctane.
3,7,11-Trimethyl-2-Tridecanol (4) (Scheme 2). This was prepared as above
for 3,7-dimethyl-2-undecanol (3) but starting from 3,4-dimethyl- -butyrolactone
(19), (trans–cis 65:35) and 1-bromo-2,6-dimethyloctane (18e). It showed by GC

PINE SAWFLY PHEROMONE PRECURSORS
1245
a threo–erythro ratio of 62:38 [iso 120 C, retention times: erythro (2S,3S,7R/S,
11R/S and 2R,3R,7R/S,11R/S, minor): 31.33 min; threo (2S,3R,7R/S,11R/S
and 2R,3S,7R/S,11R/S, major): 31.83 min]. Bp 95 C/0.65 mm Hg. nD20
=
1.4508 0.0002. IR (neat): 3358, 2961, 2926, 2872, 1462, 1377, 1099, 1003,
925, 888, 666 cm 1. 1H NMR and 13C NMR spectral data were identical to those
reported by Larsson et al. (2001). MS (EI) m/z (relative intensity): 227 (5%),
224 (M+-H2O, 3), 196 (3), 168 (2), 140 (9), 125 (87), 111 (46), 97 (55), 85 (70),
83 (55), 71 (90), 69 (80), 57 (100), 55 (73), 45 (84), 43 (55), 41 (72).
Synthesis of 3,7,9-Trimethyl-2-Tridecanol (5)
2,4-Dimethyloctanoic Acid (16c) (Scheme 1). This compound was prepared
as 2-methylhexanoic acid (16a) above but from 1-bromo-2-methylhexane (18a).
We obtained 9.1 g (0.053 mol, 57%) of the acid as a racemic mixture of syn–anti
(45:55) products. Bp 127–130 C/9 mm Hg. n2D0 = 1.4300 0.0002. IR, 1H NMR,
and 13C NMR spectral data were identical to those reported by Decicco and Grover
(1996) for (2R,4S)- and (2S,4S)-2,4-dimethyloctanoic acid).
2,4-Dimethyl-1-Octanol (17c) (Scheme 1). This compound was obtained from
the acid 16c via LiAlH4 reduction as for 17a. The alcohol (3.1 g, 0.053 mol, 86%)
was obtained as a racemic mixture of syn–anti (45:55) products and in >99.2%
purity as judged by GC. Bp 130 C/9.9 mm Hg [bp 90 C/3 mbar for (2R,4S)-2,4-
dimethyl-1-octanol (Karlsson and Hedenstro¨m, 1999)]. n2D0 = 1.4332 0.0002.
1
IR (neat): 3342, 2958, 2925, 2879, 1463, 1379, 1038 cm 1. H NMR and 13C
NMR were similar to those reported by Karlsson and Hedenstro¨m (1999) for
(2R,4S)- and (2S,4S)-2,4-dimethyl-1-octanol).
1-Bromo-2,4-Dimethyloctane (18c) (Scheme 1). This was prepared as 18b
but from 2,4-dimethyl-1-octanol (17c). Distillation {bp 110 C/6 mm Hg [bp 90 C/
7 mbar for (2S,4S)-1-bromo-2,4-dimethyloctane (Karlsson and Ho¨gberg, 2000)]}
gave the pure product as judged by GC. n2D0 = 1.4569 0.0002. IR (neat): 2958,
2927, 2871, 1459, 1379, 1228, 665, 654 cm 1. 1H NMR data were similar to those
of Karlsson and Ho¨gberg (2000) for (2S,4S)-1-bromo-2,4-dimethyloctane. Anal.
calcd for C10H21Br: C 54.3%, H 9.6%; found: C 53.9%, H 9.5%.
3,7,9-Trimethyl-2-Tridecanol (5) (Scheme 2). This was prepared as above
for 3,7-dimethyl-2-undecanol (3) but starting from 3,4-dimethyl- -butyrolactone
(19), (trans–cis 65:35) and 1-bromo-2,4-dimethyloctane (18c). It showed a threo–
erythro ratio of 64:36 analyzed by GC [CP-Wax 52CB, 30 m
0.25 mm ID,
d f = 0.25 m, carrier gas He (110 kPa), split ratio 1:30, 80 C, 0 min, then
programmed 1.0 C/min up to 250 C, retention times: erythro (2S,3S,7R/S,
9R/S and/or 2R,3R,7R/S,9R/S, minor): 57.63 min; erythro (2S,3S,7R/S,9R/S
and/or 2R,3R,7R/S,9R/S) and threo (2S,3R,7R/S,9R/S and/or 2R,3S,7R/S,
9R/S): 58.86 min; threo (2S,3R,7R/S,9R/S and/or 2R,3S,7R/S,9R/S, major):
1
59.97 min]. Bp, H NMR and 13C NMR spectral data were identical to those

¨
HEDENSTROM AND ANDERSSON
1246
reported by Karlsson and Hedenstro¨m (1999). n2D0 = 1.4510 0.0002. IR (neat):
3354, 2957, 2926, 2872, 1461, 1378, 1097, 1066, 1002, 923, 728 cm 1. MS (EI)
m/z (relative intensity): 227 (1%), 166 (2), 154 (2), 139 (7), 125 (40), 111 (40),
97 (39), 85 (58), 83 (49), 71 (67), 69 (72), 57 (100), 55 (59), 45 (64), 43 (53),
41 (74).
Synthesis of 3,8,12-Trimethyl-2-Tridecanol (12)
1-Iodo-3,7-Dimethyloctane (18f) (Scheme 1). Preparation of this compound
was according to Marshall and De Hoff (1987) but from 3,7-dimethyl-1-octanol
(17f). Distillation gave the pure product as judged by GC. Bp and n2D0 were identical
1
to those reported in Schlenk (1973). IR and H NMR data were similar to data
reported in Nagai (1976).
3,8,12-Trimethyl-2-Tridecanol (12) (Scheme 2). This was prepared as for 3,7-
dimethyl-2-undecanol (3) above but starting from 3,4-dimethyl- -butyrolactone
(19) (trans–cis 65:35) and 1-iodo-3,7-dimethyloctane (18f). It showed a threo–
erythro ratio of 65:35 by GC [iso 120 C, retention times: erythro (2S,3S,8R/S and
2R,3R,8R/S, minor): 28.20 min; threo (2S,3R,8R/S and 2R,3S,8R/S, major):
28.99 min]. Bp 120 C/0.48 mm Hg. n2D0 = 1.4486 0.0002. IR (neat): 3355,
2955, 2926, 2869, 1466, 1377, 1099, 1004, 924, 665 cm 1. 1H NMR (250 MHz)
: 0.83–0.90 (6H, m), 0.87 (6H, d, J = 6.5 Hz), 1.01–1.60 (18H, m), 1.13 (1.95H,
d, J = 6.3 Hz), 1.15 (1.05H, d, J = 6.9 Hz), 3.62–3.75 (1H, m) ppm. 13C NMR
(62.9 MHz) : 14.20, 14.55, 19.35, 19.70, 19.74, 20.31, 22.64, 22.73, 24.81, 27.40,
27.43, 27.62, 27.64, 27.74, 27.99, 32.59, 32.62, 32.71, 32.78, 32.80, 37.09, 37.12,
37.29, 37.35, 39.37, 39.83, 40.06, 71.44, 71.46, 71.80, 71.82 ppm. MS (EI) m/z
(relative intensity): 227 (5%), 224 (M+-H2O, 3), 196 (2), 154 (4), 139 (12), 138
(12), 126 (17), 125 (18), 111 (74), 97 (27), 85 (38), 83 (47), 71 (84), 69 (54),
57 (84), 55 (55), 45 (100), 43 (62), 41 (75). Anal. calcd for C16H34O: C 79.3%,
H 14.1%; found: C 79.1%, H 14.5%.
Synthesis of Erythro-(2R,3R,11R/S)-3,11-Dimethyl-2-Tetradecanol (13)
1-Bromo-2-Methylpentane (18g) (Scheme 1). This was prepared as below
for 1-bromo-2-methylnonane (18b) but from 2-methyl-1-pentanol (17g) and gave
the pure product after flash chromatography and distillation, as judged by GC.
Bp 55 C/60 mm Hg [bp 128–130 C/760 mm Hg (Ingold et al., 1986)]. nD20
=
1.4471 0.0002[n2D0 = 1.4495(Lide, 1999)]. IRdataweresimilartodatareported
1
in Crowder and Jalilian (1978)]. H NMR were similar to data in Ingold et al.
(1986).
6-Methyl-1-Nonanol (17d) (Scheme 1). This was prepared from 1-bromo-
2-methylpentane (18g) and -butyrolactone (20) using the procedure as for 3,7-
dimethyl-2-dodecanol (Bergstro¨m et al., 1995). The compound was >97% pure
as judged by GC. Bp 79–82 C/11 mm Hg [bp 110–111 C/10 mm Hg (Weitzel

PINE SAWFLY PHEROMONE PRECURSORS
1247
and Wojhan, 1951)]. n2D0 = 1.4123 0.0002. IR and 1H NMR data were similar
to data in Ge´nard and Patin (1991).
1-Bromo-6-Methylnonane (18d) (Scheme 1). This was prepared as for 1-
bromo-2-methylnonane (18b) but from 6-methyl-1-nonanol (17d). The product
was checked by 1H NMR and then used in the next step without further purification
or characterization.
Erythro-(2R,3R,11R/S)-3,11-Dimethyl-2-Tetradecanol (13) (Scheme 2). The
two-diastereomeric mixture was prepared using the same preparative procedure as
for 3,7-dimethyl-2-dodecanol (Bergstro¨m et al., 1995) starting from pure (3R,4R)-
3,4-dimethyl- -butyrolactone (19) and 1-bromo-6-methylnonane (18d). The two-
diastereomeric mixture was chemically pure. Bp 130 C/2.5 mm Hg. nD20
=
1.4502 0.0002. [ ]2D0 = +11.7 (c 4.14 n-hexane). IR (neat): 3356, 2959, 2926,
2855, 1466, 1378, 1096, 1004, 928, 722 cm 1. 1H NMR (250 MHz) : 0.84 (3H,
d, J = 6.4 Hz), 0.88 (3H, t, J = 6.7 Hz), 0.88 (3H, d, J = 6.8 Hz), 1.00–1.50
(21H, broad), 1.15 (3H, d, J = 6.4 Hz), 3.71 (1H, dq, J = 6.3, J = 4.2 Hz) ppm.
13C NMR (62.9 MHz) : 14.16, 14.43, 19.67, 20.15, 20.29, 27.08, 27.37, 29.72,
29.99, 30.02, 32.48, 32.66, 37.09, 39.42, 39.78, 71.44 ppm. MS (EI) m/z (relative
intensity):227(5%), 224(M+-H2O, 3), 194(4), 180(10), 169(2), 168(4), 152(16),
139 (7), 125 (32), 111 (50), 97 (81), 85 (60), 83 (47), 71 (61), 69 (56), 57 (81),
55 (79), 45 (100), 43 (71), 41 (78). Anal. calcd for C16H34O: C 79.3%, H 14.1%;
found: C 78.9%, H 13.8%.
Synthesis of 3,5-Dimethyl-2-Tetradecanol (14)
3,5-Dimethyl-2-Tetradecanol (14) (Scheme 2). This alcohol was prepared in
aslightlymodifiedmannerfromthebelow5,7-dimethyl-2-tetradecanol15andstar-
ted from 3,4-methyl- -butyrolactone (19), (trans–cis 65:35) and 1-bromononane
(18h). To improve the yield of the Wittig reaction by preventing cyclization of the
ketoalcohol to the hemiketal, the isolated ketoalcohol was acetylated quantitatively
according to the method of Bystro¨m et al. (1981) before performing the Wittig re-
action. 3-Methyl-5-methylene-2-tetradecanol so obtained as a mixture of isomers
was >95% chemically pure. IR (neat): 3374, 3072, 2959, 2926, 2855, 1718, 1643,
1458, 1378, 1090, 722 cm 1. 1H NMR (270 MHz) : 0.85 (3H, d, J = 6.9 Hz), 0.88
(3H, t, J = 6.7 Hz), 1.17 (3H, d, J = 6.3 Hz), 1.20–1.60 (14H, m), 1.60–1.90 (2H,
m), 1.80 (1H, bs disappears when shaken with D2O), 1.90–2.10 (2H, m), 2.12–2.30
(1H, m), 3.60–3.80 (1H, m), 4.75 (2H, d, J = 9.9 Hz) ppm. The compound was ob-
tained as a mixture of stereoisomers after hydrogenation. The diastereomeric ratio
as propionates was 32:19:17:32 [DB-5, 30 m 0.32 mm ID, d f = 0.25 m, car-
rier gas N2 (103 kPa), split ratio 1:30, 170 C, 1 min, then programmed 0.5 C/min
up to 200 C, retention times for the propionate isomers: 17.7, 18.4, 18.9, and
19.2 min]. Bp 100 C/0.06 mm Hg. n2D0 = 1.4498 0.0002. IR (neat): 3350, 2956,
1
2920, 2869, 2849, 1464, 1376, 1101, 1077, 602 cm 1. H NMR (250 MHz) :

¨
HEDENSTROM AND ANDERSSON
1248
0.81–0.91 (9H, m), 1.11 (0.48H, d, J = 4.7 Hz), 1.13 (0.72H, d, J = 4.7 Hz),
1.15 (1.80H, d, J = 6.4 Hz), 1.19–1.38 (20H, broad), 1.41 (1H, bs), 3.59–3.75
(1H, m) ppm. 13C NMR (62.9 MHz) : 13.94, 14.14, 14.35, 14.42, 18.79, 19.23,
19.35, 20.29, 20.47, 20.69, 22.70, 26.82, 26.85, 27.11, 29.37, 29.66, 29.73, 29.99,
30.02, 30.05, 30.08, 31.93, 36.14, 36.27, 36.90, 37.12, 37.32, 38.25, 39.77, 40.06,
40.51, 40.62, 71.12, 71.69, 72.10, 72.36 ppm. MS (EI) m/z (relative intensity):
227 (1%), 224 (M+-H2O, 3), 195 (9), 169 (2), 168 (6), 153 (19), 152 (19), 141 (6),
140 (8), 139 (6), 125 (18), 111 (38), 97 (87), 85 (50), 83 (37), 71 (82), 69 (60),
57 (100), 55 (68), 45 (53), 43 (66), 41 (65). Anal. calcd for C16H34O: C 79.3%, H
14.1%; found: C 79.5%, H 14.0%.
Synthesis of 5,7-Dimethyl-2-Tetradecanol (15)
2-Methylnonanoic Acid (16b) (Scheme 1). This was prepared as for 16a but
starting from 1-bromoheptane. The acid was obtained in a 51% yield and >99.5%
pure as judged by GC. Bp 76–77 C/0.5 mm Hg [bp 88–90 C/0.5 mm Hg (Nikishin
et al., 1974)]. n2D0 = 1.4249 0.0002 [n2D5 = 1.4312 for (R)-2-methylnonanoic
1
acid (Levene and Marker, 1932)]. IR data and H NMR data were similar to
Nikishin et al. (1974).
2-Methyl-1-Nonanol (17b) (Scheme 1). The compound was obtained from
the acid 16b via LiAlH4 reduction, as above for 17a, in 92% yield and was pure
as judged by GC. Bp 56–57 C/1.5 mm Hg [bp 90 C/22 mm Hg for (S)-2-methyl-
1-nonanol (Ho¨gberg et al., 1992)]. n2D0 = 1.4123 0.0002 [n2D0 = 1.4381 for (S)-
2-methyl-1-nonanol (Ho¨gberg et al., 1992)]. IR and 1H NMR data were similar to
Ho¨gberg et al. (1992) for (S)-2-methyl-1-nonanol.
1-Bromo-2-Methylnonane (18b) (Scheme 1). The compound was prepared
from 2-methyl-1-nonanol (17b) (8.06 g, 0.051 mol), which was added dropwise
to a solution of triphenylphosphine (17.1 g, 0.111 mol) and bromine (3.4 ml,
0.067 mol) in CH2Cl2 at 0 C. The mixture was stirred overnight at ambient tem-
perature. The solvent was evaporated, the residue was triturated with pentane,
and the triphenylphosphine oxide was removed by filtration. Evaporation of the
solvent, flash chromatography of the remaining oil and distillation {bp 76 C/
8 mm Hg [bp 70 C/3 mm Hg (Hedenstro¨m et al., 1992)]} gave the pure prod-
uct (9.91 g, 0.045 mol, 88%). n2D0 = 1.4530 0.0002. IR (neat): 2955, 2923,
2868, 2852, 1458, 1377, 653, 622, 602, 592 cm 1. 1H NMR (250 MHz) : 0.88
(3H, t, J = 6.6 Hz), 1.00 (3H, d, J = 6.6 Hz), 1.18–1.49 (12H, broad), 1.72–
1.84 (1H, m) 3.32 (1H, dd, J = 9.8, J = 6.2 Hz), 3.40 (1H, dd, J = 9.8, J =
5.0 Hz) ppm.
5,7-Dimethyl-2-Tetradecanol (15) (Scheme 2). This stereoisomeric mixture
was prepared using the procedure for 3,7-dimethyl-2-dodecanol (Bergstro¨m et al.,
1995) with a slight modification. An amount of 4.56 g (20.6 mmol) of 1-bromo-
2-methylnonane (18b) was added dropwise to 50 mmol finely cut lithium in

PINE SAWFLY PHEROMONE PRECURSORS
1249
20 ml Et2O at 5 C. After stirring for 2 hr, the alkyl lithium was cooled to
100 C and added dropwise to a stirred solution of 1.73 g (17.3 mmol) of
4-methyl- -butyrolactone (21) in 40 ml of Et2O at 100 C. From the recov-
ered unreacted lithium metal, the alkyl lithium produced was calculated to be
14 mmol (68%). After checking the progress of the reaction by TLC, the reaction
was quenched after 5 hr at 100 C with water (44 mmol) in THF, and the mixture
was allowed to reach ambient temperature overnight. Thereafter, 150 ml of water
and 150 ml of Et2O were added, and the organic phase was separated. The water
phase was extracted with Et2O (3 150 ml), and the pooled organic phases were
washed with brine (100 ml) and dried (MgSO4). Evaporation of the solvent left a
yellow oil, which was purified by flash chromatography to give 1.99 g (8.2 mmol)
of the ketoalcohol. The identity of the product was checked by IR and 1H 60 MHz
NMR, and the ketoalcohol was used in the next step without further purification or
characterization. To the ketoalcohol in 50 ml of dry benzene at ambient temperature
was added a dark red solution of an ylide [prepared by refluxing 14.32 g (40 mmol)
of flame-dried methyltriphenylphosphoniumbromide in dry benzene (35 ml) and
31 ml of BuLi (1.3 M in n-hexane)]. The reaction was stirred overnight and then
poured onto ice and water (400 ml). The organic phase was separated, the wa-
ter phase was extracted with Et2O (3 150 ml), the combined organic phases
were washed with aqueous 0.5 M HCl (100 ml) and aqueous saturated NaHCO3
(100 ml), and dried (MgSO4). The residue gave, after solvent evaporation and flash
chromatography, 0.90 g (3.8 mmol) of pure 7-methyl-5-methylene-2-tetradecanol
>95% as judged by GC. IR (neat): 3337, 3070, 2956, 2923, 2851, 1643, 1457,
1375, 889, 602 cm 1. 1H NMR (270 MHz) : 0.83 (3H, d, J = 6.6 Hz), 0.88 (3H,
t, J = 6.7 Hz), 1.21 (3H, d, J = 5.9 Hz), 1.20–1.40 (14H, m), 1.50–1.70 (2H, m),
1.75 (1H, bs disappears when shaken with D2O), 1.75–1.83 (1H, m), 2.00–2.18
(2H, m), 3.73–3.87 (1H, m), 4.74 (2H, d, J = 18.8 Hz) ppm. 0.83 g (3.47 mmol).
An amount of 0.83 g (3.47 mmol) of this unsaturated alcohol was dissolved
in dry methanol, and 0.07 g of 10% Pd/C was added. The reaction mixture was
hydrogenated at 1 atm for 72 hr. After removal of the catalyst and solvent, the
remaining oil was purified by flash chromatography and distillation to give 0.68 g
(2.80 mmol, total yield 16% based on the 4-methyl- -butyrolactone (4) as a mix-
ture of stereoisomers. The diastereomeric ratio judged by GC as propionates was
23:25:27:25 [iso 140 C, retention times for the propionate isomers: 13.9, 14.4,
15.6, and 15.9 min]. Bp 100 C/0.6 mm Hg. n2D0 = 1.4502 0.0002. IR (neat):
1
3335, 2955, 2921, 2867, 2849, 1462, 1375, 1118, 1069, 602 cm 1. H NMR
(250 MHz) : 0.80–1.58 (30H, m), 1.19 (3H, d, J = 6.2 Hz), 3.70–3.83 (1H, m)
ppm. 13C NMR (62.9 MHz) : 14.14, 19.45, 19.49, 19.51, 20.22, 20.27, 22.70,
23.47, 23.52, 23.57, 26.92, 26.94, 27.07, 29.41, 29.97, 29.99, 30.02, 30.04, 30.06,
30.10, 30.16, 30.18, 31.94, 32.73, 32.80, 33.87, 33.91, 36.66, 36.70, 36.83, 36.86,
37.98, 44.75, 44.78, 45.06, 45.10, 68.59, 68.63, 68.68 ppm. MS (EI) m/z (relative
intensity): 227 (2%), 181 (1), 167 (29), 140 (6), 139 (3), 125 (88), 111 (29), 97

¨
HEDENSTROM AND ANDERSSON
1250
(64), 85 (38), 83 (83), 71 (45), 69 (100), 57 (96), 55 (88), 45 (54), 43 (59), 41 (78).
Anal. calcd for C16H34O: C 79.3%, H 14.1%; found: C 79.6%, H 14.1%.
RESULTS AND DISCUSSION
Employing essentially the same synthetic methodology that we used previ-
ously, the mixture of stereoisomers of compound 3 was prepared, as shown in
Schemes 1 and 2. Racemic 2-methylhexanoic acid (16a) was prepared using the
malonic ester synthesis sequence according to the method described (Karrer et al.,
1930), and after subsequent lithium aluminum hydride (LiAlH4) reduction, 2-
methyl-1-hexanol (17a) was obtained (Scheme 1). The alcohol was converted by
way of the bromide 18a into the alkyl lithium, which was reacted with a racemic
mixture of diastereomers of 3,4-dimethyl- -butyrolactone (19) to give a ketoalco-
hol. When exposed to Huang-Minlon reduction, this gave the desired alcohol 3,7-
dimethyl-2-undecanol (3) as an eight stereoisomer mixture with a threo–erythro
ratio of 65:35 (Scheme 2).
In the same way, the mixtures of the 16 stereoisomers of 3,7,11-trimethyl-2-
tridecanol (4) (threo–erythro, 65:35), of 3,8,12-trimethyl-2-tridecanol (12) (threo–
erythro, 65:35), andof3,7,9-trimethyl-2-tridecanol(5)(threo–erythro, 64:36)were
preparedfromaracemicmixtureofdiastereomersof 3,4-dimethyl- -butyrolactone
(19) and alkyl lithiums obtained from 2,6-dimethyl-1-octanol (17e) 3,7-dimethyl-
1-octanol (17f), and 2,4-dimethyl-1-octanol (17c), respectively. 2,6-Dimethyl-
1-octanol (17e) was prepared from citronellol via tossylation, LiAlH4 reduc-
tion, allylic oxidation of the obtained 2,6-dimethyl-2-octene with SeO2, followed
by NaBH4 reduction and hydrogenation (RaNi, H2) to give the desired alcohol
(Scheme 3). 2,4-Dimethyl-1-octanol (17c) was prepared via the malonic ester
synthesis as above but from 1-bromo-2-methylhexane (18a), and after subsequent
LiAlH4 reduction of the acid 16c, the alcohol 17c was obtained (Scheme 1).
To prepare erythro-3,11-dimethyl-2-tetradecanol (13) as a mixture of two
of the possible diastereomers, the following steps were used: racemic 2-methyl-1-
pentanol (17g) was converted via the bromide 18e into the alkyl lithium, which was
reactedwith -butyrolactone(20)togiveaketoalcohol, afterHuang-Minlonreduc-
tion, gave the racemic 6-methyl-1-nonanol (17d) (Scheme 2). The alkyl lithium,
obtained as above but through the alcohol 17d and the bromide 18d, was re-
acted with the pure enantiomer of cis-(3R,4R)-3,4-dimethyl- -butyrolactone (19)
and the ketoalcohol obtained was reduced as above to give compound 13 as two
erythro-diastereoisomers without any detectable amount of threo-diastereomers
(Scheme 2).
The alcohols 3,5-dimethyl-2-tetradecanol (14) and 5,7-dimethyl-2-
tetradecanol (15) were prepared as stereoisomeric mixtures from 1-nonyl lithium
and 3,4-dimethyl- -butyrolactone (19) and from 2-methylnonyl lithium and 4-
methyl- -butyrolactone (21), respectively, as above (Scheme 2). Both 1-nonyl

PINE SAWFLY PHEROMONE PRECURSORS
1251
lithium and 2-methylnonyl lithium were prepared for the bromide 18a but via
1-bromononane (18h) or the acid 16b, the alcohol 17b, and the bromide 18b,
respectively (Scheme 1). The resulting ketoalcohols were reacted with two equiv-
alents of phosphorus ylide, and the obtained methylene group was hydrogenated to
give the products 14 and 15, respectively (Scheme 2). The alcohols 14 and 15 were
converted to the corresponding propionates and analyzed by GC for their diastere-
omeric ratios, which were found to be 32:19:17:32 and 23:25:27:25, respectively.
In conclusion, we have presented the syntheses of an eight-stereoiomeric
mixture of 3,7-dimethyl-2-undecanol (3), the precursor of the sex pheromone of
Diprion nipponica (Tai et al., 1998) and the syntheses of the 16 stereoisomeric
mixtures of 3,7,11- and 3,7,9-trimethyl-2-tridecanol (compounds 4 and 5), the pre-
cursors of the sex pheromones of M. pallipes (Bergstro¨m et al., 1998; Nakamura
and Mori, 1999; Larsson et al., 2001) and M. nemoralis (Karlsson and Hedenstro¨m,
1999; Wassgren et al., 2000), respectively. The propionate and acetate esters of
these mixtures of stereoisomers (compounds 4 and 5) have been tested in field
studies and shown to efficiently catch males of M. pallipes (Bergstro¨m et al.,
1998; Nakamura and Mori, 1999) and of M. nemoralis (Wassgren et al., 2000).
Whether the propionate ester of the eight stereoiomeric mixture of 3,7-dimethyl-
2-undecanol (3) is capable of catching males of the species Diprion nipponica
remains to be investigated in field tests. We also have presented the syntheses
of some new substances that are structurally related to sex pheromones of pine
sawfly species and the biological activities of these substances have not yet been
established.
It is important to have access to fast and trustworthy analysis methods for
elucidation of pheromone candidates found in different species of insects such
as, pine sawflies. Access to libraries of several structurally similar compounds is,
therefore, essential for the screening of, for instance, their mass spectra and GC
retention times so that structural differences may be recorded and compared with
those obtained from the natural source. This work will contribute to such a library,
which can be used when identifying new compounds found in pine sawfly species
in the future.
Acknowledgments—Financial support from the City of Sundsvall (Sundsvalls Kommun), the
Swedish Council for Forestry and Agricultural Research (SJFR), the Swedish Natural Science Re-
search Council (NFR), and the Commission of the European Communities, Agriculture and Fisheries
(FAIR), specific RTD programe, contract FAIR1-CT95-0339, “Pine sawfly pheromones for sustaiable
management of European forests” This study does not necessarily reflect the Commission’s view and
in no way anticipates its future policies.
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HEDENSTROM AND ANDERSSON
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