Synthesis of a Pheromone Component of the Screwworm Fly
1775
5.37 (1H, t, J ¼ 6:6 Hz, 3-H). NMR ꢂC (CDCl3): 0.2,
14.1, 19.7, 21.1, 22.65, 22,68, 24.9, 27.0, 27.1, 29.1,
29.4, 29.5, 29.65, 29.67, 29.70, 29.73, 29.9, 30.0, 31.6,
31.9, 32.8, 34.8, 37.08, 37.1, 64.4, 90.2, 102.8, 169.9.
Anal. Found: C, 75.92; H, 12.59%. Calcd. for
C31H60O2Si: C, 75.54; H, 12.27%.
(1H, dt, J ¼ 0:2, 1.2 Hz, 1-H), 4.37 (1H, J ¼ 0:2,
2.7 Hz, 3-H). NMR ꢂc (CDCl3): 14.1, 19.7, 22.6, 22.7,
25.0, 27.04, 27.09, 29.2, 29.4, 29.56, 29.66, 29.74, 29.9,
30.0, 31.9, 32.7, 37.07, 37.09, 37.6, 62.3, 72.8, 85.0.
Anal. Found: C, 83.02; H, 13.48%. Calcd. for C26H50O:
C, 82.46; H, 13.31%.
(ii) (3RS,11S)-Isomer. In the same manner as that
described for enzymatic acetylation of (3RS,11R)-13,
(3RS,11S)-13 (4.4 g) gave (3S,11S)-13 (1.2 g, 55%) and
(3R,11S)-14 (2.2 g, 88%). The alcohol (3S,11S)-13 was
(iv) (3R,11S)-Isomer. In the same manner as describ-
ed for (3R,11R)-15, (3R,11S)-14 (1.3 g) gave (3R,11S)-
22
26
15 (0.87 g, 87%) as an oil, nD 1.4619, ½ꢀꢁD þ3:0 (c
2.3, hexane). Its IR, 1H- and 13C-NMR spectra were
identical with those reported for (3S,11R)-15. Anal.
Found: C, 82.27; H, 13.32%. Calcd. for C26H50O: C,
82.46; H, 13.31%.
23
26
an oil, nD 1.4620. ½ꢀꢁD ꢂ1:7 (c 3.0, hexane). Its IR,
1H- and 13C-NMR spectra were virtually identical with
those reported for (3RS,11S)-13. Anal. Found: C, 77.22;
H, 12.95%. Calcd. for C29H58OSi: C, 77.26; H, 12.97%.
26
The acetate (3R,11S)-14 was also an oil, nD 1.4562,
11-Methylpentacos-1-yn-3-ol TBS Ether (16).
22
1
½ꢀꢁD þ26:2 (c 3.3, hexane). Its IR, H- and 13C-NMR
spectra were virtually identical with those reported for
(3R,11R)-14. Anal. Found: C, 75.14; H, 12.27%. Calcd.
for C31H60O2Si: C, 75.54; H, 12.27%.
(i) (3R,11R)-Isomer. To a stirred and ice-cooled
solution of (3R,11R)-15 (1.35 g, 3.6 mmol) in dry DMF
(10 ml) were added imidazole (0.98 g, 14 mmol) and
TBSCl (0.65 g, 4.3 mmol). The mixture was stirred
overnight at room temperature, then poured into ice-
water and extracted with hexane. The extract was
washed successively with water and brine, dried with
MgSO4, and concentrated in vacuo. The residue was
chromatographed over SiO2 (25 g). Elution with hexane
11-Methylpentacos-1-yn-3-ol (15).
(i) (3R,11R)-Isomer. To a stirred solution of (3R,11R)-
14 (1.65 g, 3.3 mmol) in MeOH (30 ml) and H2O (2 ml)
was added K2CO3 (2.0 g, 14 mmol). The suspension was
stirred for 2 d at room temperature. The mixture was
then diluted with water and extracted with hexane. The
extract was washed with water and brine, dried with
MgSO4, and concentrated in vacuo. The residue was
chromatographed over SiO2 (15 g in hexane). Elution
with hexane/EtOAc (50:1) gave (3R,11R)-15 (1.0 g,
79%) as a solid. Recrystallization from acetone yielded
an analytical sample of (3R,11R)-15 as needles, mp
26
gave (3R,11R)-16 (1.3 g, 74%) as an oil, nD 1.4540,
25
½ꢀꢁD þ18:4 (c 2.22, hexane). IR ꢃmax (film) cmꢂ1
:
3310 (m), 1260 (m), 1080 (s), 840 (s), 760 (m). NMR ꢂH
(CDCl3): 0.10, 0.12 (6H, SiMe), 0.83 (3H, d,
J ¼ 6:3 Hz, 11-Me), 0.88 (3H, t, J ¼ 6:9 Hz, 25-H),
0.91 (9H, s, t-Bu), 1.00–1.18 (2H, m), 1.18–1.50 [1.26
(br. s), 37H, m], 1.60–1.74 (2H, m, 4-H), 2.36 (1H, d,
J ¼ 2:1 Hz, 1-H), 4.33 (1H, dt, J ¼ 2:1, 6.3 Hz, 3-H).
NMR ꢂc (CDCl3): ꢂ5:1, ꢂ4:6, 14.1, 18.2, 19.7, 22.66,
22.70, 25.1, 25.8, 27.06, 27.11, 29.26, 29.38, 29.60,
29.67, 29.72, 29.76, 29.9, 30.1, 31.6, 31.9, 32.8, 37.09,
37.11, 38.6, 62.8, 74.8, 85.8. Anal. Found: C, 76.53; H,
12.71%. Calcd. for C32H64OSi: C, 77.97; H, 13.09%.
This TBS ether was slightly volatile and did not give
correct analytical data.
25
38.0–38.5 ꢀC, ½ꢀꢁD þ4:3 (c 0.84, hexane). IR ꢃmax
(nujol) cmꢂ1: 3285 (m), 1065 (m), 630 (m). NMR ꢂH
(CDCl3): 0.83 (3H, d, J ¼ 6:3 Hz, 3-Me), 0.86 (3H, t,
J ¼ 6:6 Hz, 25-H), 1.00–1.18 (2H, m), 1.18–1.52 [1.26
(br. s), 38H, m], 1.65–1.78 (2H, m, 4-H), 2.46 (1H, d,
J ¼ 2:4 Hz, 1-H), 4.37 (1H, dt, J ¼ 2:4, 6.6 Hz, 3-H).
NMR ꢂc (CDCl3): 14.1, 19.7, 22.7, 25.0, 27.1, 29.2,
29.4, 29.6, 29.66, 29.74, 29.9, 30.0, 31.9, 32.8, 37.08,
37.10, 37.7, 62.4, 72.8, 85.0. Anal. Found: C, 81.84; H,
13.41%. Calcd. for C26H50O: C, 82.46; H, 13.31%.
(ii) (3S,11S)-Isomer. In the same manner as described
for (3R,11R)-15, (3S,11S)-13 (1.05 g) gave (3S,11S)-15
(0.83 g, 92%). Recrystallization from acetone yielded an
(ii) (3S,11R)-Isomer. In the same manner as described
for (3R,11R)-16, (3S,11R)-15 (0.79 g) gave (3S,11R)-16
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(0.82 g, 80%) as an oil, nD 1.4518, ½ꢀꢁD ꢂ18:9 (c
2.34, hexane). Its IR, H- and 13C-NMR spectra were
1
virtually identical with those reported for (3R,11R)-16.
Anal. Found: C, 74.31; H, 12.53%. Calcd. for
C32H64OSi: C, 77.97; H, 13.09%.
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analytical sample as needles, mp 37.5–38.0 ꢀC, ½ꢀꢁD
ꢂ4:0 (c 2.24, hexane). Its IR, 1H- and 13C-NMR spectra
were identical with those reported for (3R,11R)-15.
Anal. Found: C, 82.30; H, 13.45%. Calcd. for C26H50O:
C, 82.46; H, 13.31%.
(iii) (3R,11S)-Isomer. In the same manner as describ-
ed for (3R,11R)-16, (3R,11S)-15 (0.57 g) gave (3R,11S)-
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16 (0.59 g, 73%) as an oil, nD 1.4500, ½ꢀꢁD þ14:1 (c
2.40, hexane). Its IR, H- and 13C-NMR spectra were
1
(iii) (3S,11R)-Isomer. In the same manner as describ-
ed for (3R,11R)-15, (3S,11R)-13 (0.90 g) gave (3S,11R)-
identical with those reported for (3S,11R)-16. Anal.
Found: C, 75.70; H, 12.52%. Calcd. for C32H64OSi: C,
77.97; H, 13.09%.
(iv) (3S,11S)-Isomer. In the same manner as described
for (3R,11R)-16, (3S,11S)-15 (0.78 g) gave (3S,11S)-16
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15 (0.51 g, 66%) as an oil, nD 1.4621, ½ꢀꢁD ꢂ4:0 (c
2.38, hexane). IR ꢃmax (film) cmꢂ1: 3310 (m), 1025 (m),
655 (m). NMR ꢂH (CDCl3): 0.83 (3H, d, J ¼ 6:3 Hz, 11-
Me), 0.88 (3H, t, J ¼ 6:6 Hz, 25-H), 1.10–1.18 (2H, m),
1.18–1.40 [1.26 (br. s), 35H, m], 1.40–1.52 (2H, m, 5-
H), 1.60–1.80 (2H, m, 4-H), 2.05 (1H, br. s, OH), 2.45
25
26
(0.83 g, 82%) as an oil, nD 1.4550, ½ꢀꢁD ꢂ20:0 (c
2.21, hexane). Its IR, H- and 13C-NMR spectra were
identical with those of (3R,11R)-16. Anal. Found: C,
1