Synthesis of the racemate of (Z)-exo-alpha-bergamotenal, a pheromone component of the white-spotted spined bug, Eysarcoris parvus Uhler.

Article abstract of DOI:10.1271/bbb.66.1415

The racemate of (Z)-exo-alpha-bergamotenal, a sex pheromone component of the white-spotted spined bug, was synthesized from racemic exo-alpha-bergamotene by a five-step sequence involving regioselective epoxidation and (Z)-selective Wittig olefination reactions. The 1H- and 13C-NMR spectra of the synthetic sample were identical with those of the natural material.

Full text of DOI:10.1271/bbb.66.1415

Biosci. Biotechnol. Biochem., 66 (6), 1415–1418, 2002
Note
Synthesis of the Racemate of (Z )-exo-a-Bergamotenal, a Pheromone
Component of the White-spotted Spined Bug, Eysarcoris parvus Uhler
Babak Heidary ALIZADEH, Shigefumi KUWAHARA,† Walter Soares LEAL,1 and
#
2,
Hong-Chao MEN
Laboratory of Applied Bioorganic Chemistry, Division of Life Science, Graduate School of Agricultural
Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan
1Honorary Maeda-DuŠey Laboratory, Department of Entomology, University of California Davis,
1 Shields Ave., Davis, CA 95616-8585, USA
2Laboratory of Chemical Prospecting, National Institute of Sericultural and Entomological Science,
1-2 Ohwashi, Tsukuba 305-8634, Japan
Received January 7, 2002; Accepted February 4, 2002
The racemate of (
pheromone component of the white-spotted spined bug,
was synthesized from racemic exo -bergamotene by a
Z
)-exo
-
a
-bergamotenal, a sex
plant sources, except for one case, in which a-trans-
bergamotol acetate was obtained as a volatile
metabolite from Caribbean coral of the genus Gorgo-
nia, although the geometry of the double bond was
not speciˆed.8) This unique ˆnding prompted us to
embark on the synthesis of 1 to conˆrm the proposed
structure and to supply a su‹cient amount of the
sample for biological studies. To begin with, we
report in this note the synthesis of the racemate of 1.
Known bicyclic ketone 3a,9,10) which had been
prepared from farnesic acid chloride (2) via [2+2]
cycloadditon of an intermediary vinylketene, was
ˆrst treated with hydrazine in acetic acid to give the
corresponding hydrazone (3b).9) According to
Corey's method,9) this hydrazone (3b) was exposed to
-
a
ˆve-step sequence involving regioselective epoxidation
1
and (
Z
)-selective Wittig oleˆnation reactions. The H-
and 13C-NMR spectra of the synthetic sample were iden-
tical with those of the natural material.
Key words: bergamotenal; sesquiterpene; pheromone;
white-spotted spined bug; Eysarcoris par-
vus
The white-spotted spined bug (Eysarcoris parvus
Uhler) is a notorious pest to many agricultural crops,
especially for rice production in Japan. A few years
ago, we reported the presence of the male-speciˆc sex
pheromone of the stink bug consisting of three com-
ponents,1,2) and quite recently, the structure of one of
basic conditions (tert-BuOK, DMSO) to obtain D2,15
oleˆnic hydrocarbon 4a (exo -bergamotene), which
is known to be convertible into the corresponding
-
-
b
D
2,3-oleˆn (4b, exo
-a-bergamotene) by treating with
these components was proposed to be (Z )-exo-a-
hydriodic acid in benzene.11) To our surprise,
however, this WolŠ-Kishner reduction directly gave
bergamotenal (1) from analyses of its IR, MS, and
NMR data (Leal, W. S., Men, H.-C., Kuwahara,
S., Hasegawa, M., manuscript in preparation).
Although this aldehyde (1) had been prepared for use
the thermodynamically more stable
D
2,3-product (4b)
＝
almost exclusively (4a:4b ca. 1:27) instead of 4a
which had previously been obtained by Corey and
in perfumery from (Z )-exo-a-bergamotenol (8) con-
Desai.9) The double bond migration from the D2,15
-
tained in sandalwood essential oil,3,4) our literature
survey revealed 1 to be a new naturally occurring
compound. From the standpoint of chemical ecolo-
gy, it is worth mentioning that structurally related en-
do-bergamotane-type sesquiterpenes (9 and 10) have
been isolated from wild tomato leaves (Lycopersicon
position to the
ascribable to the reaction time and temperature ap-
plied, since 3b was treated with potassium tert
D
2,3-position is considered to be
-
butoxide in DMSO for 12 h at room temperature in
the preceding experiment,9) while in our case, the
hydrazone (3b) was exposed to basic conditions for a
hirsutum
)
as components of the oviposition
stimulant of the corn earthworm (Heliothis zea).5–7)
To the best of our knowledge, however, the isolation
of 1 from the stink bug is the ˆrst example of obtain-
ing bergamotane-type natural products from non-
9
longer period (30 h) at a higher temperature (65 C).
In order to conˆrm this presumption, the reduction
was repeated by using exactly the same conditions as
those reported in the literature.9) Under these condi-
†
To whom correspondence should be addressed. Phone & Fax: +81-22-717-8783; E-mail: skuwahar
＠
biochem.tohoku.ac.jp
#
Present address: Experiment & Research Center, Japan Applied Microbiology Research Institute Co. LTD, Yamanashi Business Park
D-3, Nitanda 326-9, Otoguro, Tamaho-cho, Nakagoma, Yamanashi 409-3812, Japan

1416
B. H. ALIZADEH et al.
form is now underway to determine the absolute con-
ˆguration of 1.
Experimental
IR spectra were measured with a Jasco IR Report-
1
100 spectrometer. H-NMR spectra were recorded
with a Varian Gemini 2000 (300 MHz) spectrometer
in CDCl3 with tetramethylsilane as an internal stan-
dard, unless otherwise stated. Mass spectra were
recorded with a Jeol JMS-700 spectrometer. Merck
silica gel 60 (70–230 mesh) was used for column chro-
matography.
*
*
*
(1R ,5R ,6S )-2,6-Dimethyl-6-(4-methyl-3-
pentenyl)bicyclo[3.1.1]hept-2-ene (4b). To a stirred
solution of 3a (1.41 g, 6.47 mmol) and acetic acid
(0.55 ml, 9.61 mmol) in absolute ethanol (97 ml) was
added anhydrous hydrazine (1.24 g, 38.7 mmol), and
9
the mixture was stirred at 30 C for 48 h. The mixture
was then diluted with ether (300 ml), and the result-
ing ethereal solution was successively washed with
1
M
NaOH aq. and brine, dried (MgSO4) and concen-
trated in vacuo to give 1.70 g of crude 3b as a yellow
oil; IR
max cm„1: 3350 (m), 3070 (w), 1690 (m), 1640
(m). As described in the text, compound 3b was con-
n
Figure. Reagents: a) N2H4, AcOH, EtOH; b) t-BuOK, DMSO; c)
verted into a 1:27 mixture of 4a and 4b in a 42
z yield
m
-CPBA, aq. NaHCO3, CH2Cl2; d) H5IO6, H2O-THF; e) NaH,
by treating with potassium tert-butoxide in DMSO
(
o-Tolyl-O)2P(O)CH(CH3)CO2Et, THF; f) DIBAL, THF; g)
for 30 h at 65. However, by raising the reaction tem-
MnO2, hexane
9
perature to 85 C, the reaction time could be short-
tions, 4a was indeed obtained as the major product
ened to 15 h, and the chemical yield of 4b was im-
proved to 52 , while the ratio of 4a and 4b (1:27)
＝
(4a:4b ca. 7:1). Furthermore, when the
D
2,15-oleˆn-
z
ic compound (4a) was treated with tert-BuOK in
DMSO at 60 C for 28 h, it was gradually trans-
was maintained, as shown in the following descrip-
tion. Crude hydrazone 3b (1.70 g) was dissolved in
DMSO (64 ml), and potassium tert-butoxide (7.89 g,
70.3 mmol) was added to the solution. The mixture
9
formed into 4b, producing a 1:27 mixture of 4a and
4b. These results clearly show that the isomerization
of the initially formed
D
2,15-oleˆnic reduction
was stirred at 85
9C for 15 h, and then diluted with
product (4a) into the
D
2,3-oleˆn (4b) was brought
pentane (400 ml). The pentane solution was succes-
about during the WolŠ-Kishner reduction by expos-
ing 4a to the prolonged reaction time and higher tem-
perature under the strongly basic conditions. After
chromatographic puriˆcation, the diene (4b) was
sively washed with 1
M
HCl aq. and brine, dried
(MgSO4) and concentrated in vacuo. The residue
(0.76 g) was chromatographed over silica gel (58 g,
eluted with hexane) to give 0.680 g (52
z
) of 4b and
＝
0.025 g (2 ) of 4a. 4b: Rf 0.78 [Merck silica gel 60
z
subjected to an epoxidation reaction by using
m
-
chloroperbenzoic acid. Fortunately, this oxidation
proceeded regioselectively to give a mixture of 5 and
bis-epoxidation product 5' in a ratio of 6.6:1. This
selectivity was probably due to steric hindrance
F254 (No. 5715), developed with hexane]; IR nmax
cm„1: 3020 (w), 2920 (s), 1465 (m), 1375 (m), 1215
(w), 1120 (w), 1085 (w), 1015 (w), 890 (w), 790 (m);
1H-NMR
d: 0.83 (3H, s, 6-CH3), 1.17 (1H, d,
around the
of 5 was cleaved with periodic acid to give aldehyde
6, which was then exposed to ( )-selective Wittig
oleˆnation conditions12) to give 7 in an 83
yield af-
D
2,3-double bond of 4b. The epoxide ring
J
＝
br s, 4
8.5 Hz, 7-H), 1.58–1.74 (2H, m, 1
?
-H), 1.63 (3H,
＝
?
-CH3), 1.66 (3H, q,
J
1.7 Hz, 2-CH3), 1.70
Z
(3H, br s, 4?-CH3), 1.91–2.06 (3H, m), 2.08–2.19
＝
(2H, m), 2.20–2.30 (1H, m, 4-H), 2.32 (1H, dt, J
z
＝
7.1 Hz, 3?-H),
ter chromatographic puriˆcation. This ester (7) was
reduced with diisobutylaluminum hydride to aŠord
allylic alcohol 8. Finally, oxidation of 8 with man-
8.5, 5.8 Hz, 7-H), 5.17 (1H, tm,
J
5.18–5.23 (1H, m, 3-H); HREIMS m z (M+): calcd.
W
for C15H24, 204.1878; found, 204.1881. The 1H-NMR
±
ganese dioxide completed the synthesis of ( )-1. The
spectral data of 4b were identical with those reported
1H- and 13C-NMR spectra of the synthetic sample
were identical to those of the natural pheromone
component. The synthesis of 1 in an optically active
in the literature.11) 4a: Rf 0.69 [Merck silica gel 60
＝
F254 (No. 5715), developed with hexane]; IR nmax
cm„1: 3070 (w), 2950 (s), 2925 (s), 2850 (s), 1640 (w),

±
Synthesis of ( )-(
Z
)-exo
-
a
-Bergamotenal
1417
1460 (m), 1380 (m), 880 (w); 1H-NMR
d
: 0.71 (3H, s,
NaHCO3 aq. and brine, dried (MgSO4) and concen-
trated in vacuo. The residue (0.48 g) was chro-
matographed over silica gel (30 g, hexane-ethyl
＝
6-CH3), 1.42 (1H, d,
(2H, m), 1.62 (3H, 4
J
9.9 Hz, 7-H), 1.54–1.68
?-CH3), 1.70 (3H, s, 4?-CH3),
1.78–1.86 (2H, m), 1.89–2.09 (3H, m), 2.20–2.35
(2H, m), 2.46–2.63 (2H, m), 4.56 (1H, br s, 2-methy-
acetate, 8:1) to give 340 mg (81z) of 6. IR n :
max cm„1
2960 (s), 2920 (s), 2880 (s), 2715 (w), 1725 (s), 1470
(w), 1445 (m), 1375 (m), 1260 (m), 1100 (m), 1025
lene), 4.62–4.64 (1H, m, 2-methylene), 5.16 (1H, tm,
1
1
＝
J
7.4 Hz, 3
?
-H). The H-NMR spectral data of 4a
(m), 805 (m); H-NMR
d
: 0.81 (3H, s, 6
?-CH3), 1.21
were identical with those reported in the literature.9)
(1H, d,
J
8.8 Hz, 7
?
-H), 1.66 (3H, q,
J
＝
＝
1.8 Hz,
2?
-CH3), 1.89–2.01 (3H, m), 2.08–2.19 (2H, m),
2.22–2.33 (1H, m, 4 -H), 2.32 (1H, dt, 8.8,
5.5 Hz, 7 -H), 2.39–2.49 (2H, m), 5.22 (1H, br s,
Isomerization of 4a into 4b
.
A mixture of 4a
?
J
＝
(16.0 mg, 0.0784 mmol) and potassium tert-butoxide
?
＝
1.9 Hz, CHO); HREIMS m z
(48.0 mg, 0.428 mmol) in DMSO (1 ml) was stirred at
3?
-H), 9.84 (1H, t,
J
W
60
9
C for 28 h. The mixture was diluted with hexane
(M+): calcd. for C12H18O, 178.1358; found,
178.1355.
and successively washed with 1
M
HCl aq. and brine.
The organic layer was dried (MgSO4) and concentrat-
1
*
*
*
ed in vacuo to give an oil (10 mg), whose H-NMR
Ethyl (Z)-5-[(1R ,5R ,6S )-2,6-dimethylbicyclo
[3.1.1]hept-2-en-6-yl]-2-methyl-2-pentenoate ( ). To
a stirred suspension of NaH (60 in mineral oil,
analysis revealed that the crude product was a 27:1
7
mixture of 4b and 4a.
z
77.3 mg, 1.93 mmol, washed 3 times with hexane
under argon) in THF (5 ml) was added a solution of
*
*
*
(1R ,5R ,6S )-2,6-Dimethyl-6-(4-methyl-3,4-
epoxypentyl)bicyclo[3.1.1]hept-2-ene
stirred mixture of 4b (550 mg, 2.70 mmol), 0.5
NaHCO3 aq. (19.5 ml, 9.75 mmol) and dichloro-
methane (24 ml) was added a solution of
chloroperbenzoic acid (65 , 720 mg, 2.71 mmol) in
dichloromethane (32 ml) over 2 h at 0 C. After 4 h,
the mixture was successively washed with 1 NaOH
(
5
). To
a
ethyl 2-(di-
1.44 mmol) in THF (5 ml) at 0
was stirred at 15 C for 15 min. To this mixture was
added dropwise a solution of 6 (220 mg, 1.23 mmol)
in THF (7 ml) at „78 C. The mixture was stirred at
the same temperature for 30 min, and then allowed to
warm gradually to 0 C over 2 h. The mixture was
o
-tolylphosphono)propionate (500 mg,
M
9
C, and the mixture
9
m
-
z
9
9
M
9
aq. and water, dried (Na2SO4) and concentrated in
vacuo. The residue (0.73 g) was chromatographed
over silica gel (30 g, hexane-ethyl acetate, 9:1) to give
poured into sat. NH4Cl aq. and extracted with ethyl
acetate. The organic layer was successively washed
with water and brine, dried (MgSO4) and concentrat-
ed in vacuo. The residue was chromatographed over
silica gel (15 g, hexane-ethyl acetate, 10:1) to give
510 mg (86
z z
) of 5 along with 80 mg (13 ) of 5?. 5:
IR nmax cm„1: 2955 (s), 2920 (s), 2875 (m), 1445 (m),
1375 (s), 1320 (w), 1245 (w), 1215 (w), 1120 (m), 1095
270 mg (83
z
) of 7. IR nmax cm„1: 2975 (s), 2950 (s),
(w), 870 (w), 790 (w); 1H-NMR
d
: 0.82 (3H, s,
2920 (vs), 2875 (s), 1715 (vs), 1450 (m), 1370 (m),
1220 (s), 1180 (s), 1160 (m), 1105 (m), 1080 (w), 1030
6-CH3), 1.19 (1H, d,
J
＝
8.5 Hz, 7-H), 1.29 (3H, s,
1
4
?
-CH3), 1.32 (3H, s, 4
?
-CH3), 1.62–1.74 (2H, m,
(w); H-NMR
d
: 0.84 (3H, s, 6
?
-CH3), 1.18 (1H, d,
＝
＝
＝
7.1 Hz, O-C-CH3),
1?-H), 1.65 (3H, q,
J
1.9 Hz, 2-CH3), 1.88–2.06
J
8.5 Hz, 7
1.65 (3H, q,
5-H2), 1.90 (3H, d,
t, 5.6 Hz, 1
(1H, m), 2.32 (1H, dt,
2.40–2.52 (2H, m), 4.21 (2H, q,
?
-H), 1.30 (3H, t,
J
(3H, m), 2.08–2.18 (2H, m), 2.20–2.32 (1H, m, 4-H),
2.32 (1H, dt,
J
＝
1.6 Hz, 2
?
-H), 1.65–1.75 (2H, m,
＝
＝
1.1 Hz, 2-CH3), 2.01 (1H, br
J
8.5, 5.8 Hz, 7-H), 2.74 (1H, t,
J
J
＝
6.2 Hz, 3
?
-H), 5.21 (1H, br s, 3-H); HREIMS
J
＝
?-H), 2.08–2.18 (2H, m), 2.20–2.32
m z (M+): calcd. for C15H24O, 220.1827; found,
J
8.5, 5.6 Hz, 7?-H),
＝
W
: IR nmax cm„1: 2950 (s), 2920 (s), 2870
J
7.1 Hz, O-CH2),
＝
220.1828. 5
?
(m), 1440 (m), 1375 (s), 1320 (w), 1245 (w), 1120 (m),
5.18–5.23 (1H, m, 3?-H), 5.98 (1H, tq, J 7.4,
＝
1
1090 (w), 870 (w), 790 (w); H-NMR
d
: 0.92 (3H, s,
1.1 Hz, 3-H); HREIMS m z (M+): calcd. for
W
6-CH3), 1.28 (3H, d,
-CH3), 1.33 (3H, s, 4
1.76–1.89 (2H, m), 1.89–2.07 (2H, m), 2.73 (1H, t,
J
＝
1.4 Hz, 2-CH3), 1.32 (3H, s,
C17H26O2, 262.1933; found, 262.1935.
4?
?-CH3), 1.42–1.76 (4H, m),
*
*
*
(Z)-5-[(1R ,5R ,6S )-2,6-Dimethylbicyclo[3.1.1]
hept-2-en-6-yl]-2-methyl-2-penten-1-ol ). To
stirred solution of 7 (62.1 mg, 0.237 mmol) in THF
(5 ml) was added dropwise a 1 solution of
diisobutylaluminium hydride in hexane (1.3 ml,
1.3 mmol) at „78 C. After 4 h, the reaction mixture
J
＝
6.2 Hz, 3?-H), 3.08 (1H, br d,
J
＝
4.0 Hz, 3-H);
(
8
a
HREIMS m z (M+): calcd. for C15H24O2, 236.1776;
W
found, 236.1775.
M
*
*
*
3-[(1R ,5R ,6S )-2,6-Dimethylbicyclo[3.1.1]hept-
2-en-6-yl]propanal ( ). To a stirred solution of 5 (520
9
6
was quenched with water (1.3 ml) and ˆltered
through a Celite pad. The ˆltrate was dried over
MgSO4 and concentrated in vacuo. The residue
(66.3 mg) was chromatographed over silica gel (30 g,
mg, 2.36 mmol) in THF (3 ml) was added dropwise a
solution of periodic acid (730 mg, 3.20 mmol) in
water (1.9 ml) at 0 C. After 3 h, the mixture was
9
poured into water and extracted with ether. The
ethereal solution was successively washed with sat.
hexane-ethyl acetate, 10:1) to give 52.0 mg (99.7
z)
of 8. IR
n
max cm„1: 3310 (m), 3010 (w), 2950 (s), 2910

1418
B. H. ALIZADEH et al.
(s), 2870 (s), 1440 (m), 1370 (m), 1260 (m), 1090 (m),
tion, Science, Sports and Culture, Japan (No.
13660103). We are grateful to Ms. T. Yamada
(Tohoku University) for measuring the mass spectra.
1
1015 (s), 800 (m), 785 (m); H-NMR
d
: 0.83 (3H, s,
-H), 1.56 (1H, br
s, OH), 1.58–1.71 (2H, m, 5-H2), 1.65 (3H, q,
1.9 Hz, 2 -CH3), 1.81 (3H, d, 1.4 Hz, 2-CH3),
1.96–2.18 (5H, m), 2.21–2.30 (1H, m, 4 -H), 2.30
-H), 4.16 (2H, br s, 1-H2),
＝
8.5 Hz, 7?
6?-CH3), 1.18 (1H, d,
J
References
J
＝
?
J
＝
1) Men, H.-C., Yabu, T., Kim, J.-Y., and Leal, W. S.,
Evidence of male-produced sex pheromone in the
white spotted spined stink bug Eysarcoris parvus
(Heteroptera: Pentatomidae). First Asia-Paciˆc
Conference on Chemical Ecology, Shanghai, China,
Abstracts p. 57, 1–4 November (1999).
?
＝
8.5, 5.7 Hz, 7?
(1H, dt,
J
＝
7.6 Hz,
5.19–5.23 (1H, m, 3
?
-H), 5.36 (1H, br t,
J
3-H); HREIMS m z (M+): calcd. for C15H24O,
W
220.1827; found, 220.1833.
2) Men, H.-C., Yabu, T., and Leal, W. S., Diel rhythm
of reproductive activity and its temporal correlation
with release of male-speciˆc sex pheomones in the
white spotted spined bug Eysarcoris parvus (Heterop-
tera: Pentatomidae). Entomologia Sinica, 8, 101–113
(2001).
*
*
*
(Z)-5-[(1R ,5R ,6S )-2,6-Dimethylbicyclo[3.1.1]
hept-2-en-6-yl]-2-methyl-2-pentenal ( ). A mixture of
1
8 (38.0 mg, 0.173 mmol) and manganese dioxide
(chemically treated, purchased from Wako Pure
Chemical Industries, 0.31 g, 3.6 mmol) in dry hexane
3) Brunke, E. J.,
a-trans-Bergamotol-Derivaten als
(7 ml) was stirred at 09C for 24 h. The mixture was
Reich- und AromastoŠe. German Patent DE 3205320
(Aug. 18, 1983); CA, 100, 6890v (1984).
ˆltered through a Celite pad, and the ˆltrate was con-
centrated in vacuo. The residue (49 mg) was chro-
matographed over silica gel (18 g, hexane-ethyl
4) Chapuis, C., Barthe, M., Muller, R. L., and Schulte-
Elte, K. H., Preparation and absolute conˆguration
acetate, 10:1) to give 37.4 mg (99
z
) of 1. IR nmax
of („)-(E )-a-trans-bergamotenone. Helv. Chim.
cm„1: 3015 (w), 2945 (s), 2910 (s), 2870 (s), 2720 (w),
1675 (vs), 1635 (w), 1440 (m), 1370 (m), 1340 (w),
Acta, 81, 153–162 (1998).
5) Coates, R. M. and Denissen, J. F., Identiˆcation of
1
1260 (m), 1080 (m), 1015 (m), 800 (m); H-NMR
a
-santalenoic and endo-b-bergamotenoic acids as
moth oviposition stimulants from wild tomato leaves.
J. Org. Chem., 53, 2186–2192 (1988).
(C6D6) d: 0.76 (3H, s, 6?-H), 1.24 (1H, d, J 8.8 Hz,
＝
7?-H), 1.40–1.48 (2H, m, 5-H2), 1.64 (3H, q,
6) Douglass, S. K., Juvik, J. A., Pyun, H.-J., and
Coates, R. M., Structure-activity relationships for
＝
＝
J
2.0 Hz, 2
1.86 (1H, dt,
m, 5 -H), 2.01–2.28 (5H, m, 4-H2, 4
5.20–5.26 (1H, m, 3 -H), 6.00 (1H, dt,
8.2 Hz, 3-H), 10.12 (1H, s, CHO); 13C-NMR (C6D6)
: 16.5, 17.2, 22.4, 22.9, 31.3, 31.6, 38.7, 39.0, 41.2,
?-H), 1.76 (3H, d,
J
1.4 Hz, 2-CH3),
-H), 1.92–1.99 (1H,
-H2, 7 -H),
1.4,
J
＝
1.3, 5.6 Hz, 1
?
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?
?
?
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45.4, 117.0, 135.9, 144.2, 148.6, 189.9. The H- and
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tical with those of the natural pheromone compo-
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bergamoten-12-oic acids -form, -form), moth
(
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b
oviposition stimulants isolated from wild tomato
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of 1 in other solvents. 1H-NMR (CDCl3)
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: 0.87 (3H,
-H), 1.66 (3H,
-CH3), 1.74–1.82 (2H, m, 5-H2),
1.78 (3H, br s, 2-CH3), 2.01 (1H, br t, 5.5 Hz,
-H), 2.10–2.20 (2H, m), 2.22–2.35 (2H, m),
2.50–2.64 (2H, m), 5.23 (1H, br s, 3 -H), 6.59 (1H, t,
8.0 Hz, 3-H), 10.19 (1H, s, CHO); 1H-NMR
(CCl4) : 0.87 (3H, s, 6 -CH3), 1.22 (1H, d,
8.8 Hz, 7 -H), 1.67 (3H, br s, 2 -CH3), 1.73–1.84
(2H, m, 5-H2), 1.75 (3H, br s, 2-CH3), 2.00 (1H, br t,
s, 6?-CH3), 1.22 (1H, d, J 8.8 Hz, 7?
＝
＝
1.6 Hz, 2?
q,
J
J
＝
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＝
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m), 2.51–2.66 (2H, m), 5.20 (1H, br s, 3
b
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W
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literature.3)
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Acknowledgments
12) Ando, K.,
reaction of
Z
-selective Horner-Wadsworth-Emmons
-substituted ethyl (diarylphosphono)
a
This work was supported, in part, by grant-aid for
scientiˆc research (C) from the Ministry of Educa-
acetates with aldehydes. J. Org. Chem., 63,
8411–8416 (1998).