Synthesis of Tribolure, the Common Aggregation Pheromone of Four Tribolium Flour Beetles
to afford light yellow oil, which was purified by flash
column chromatography on silica gel (petroleum
ether/EtOAc: 10/1, V/V) to afford the title compound
31.6 (CH2), 29.7(CH2), 24.6 (CH2), 19.7 (CH3), 19.4
(CH3), 11.6 (CH3); IR (KBr) ν: 3078, 2927, 1641, 1462,
1378, 992, 909 cm−1; HRMS-EI (m/z): M+ calcd for
C13H26: 182.2035, found 182.2043.
1
(1.3 g, 83%) as a colorless oil. H NMR (400 MHz,
CDCl3) δ: 3.51-3.47 (dd, J=10.4, 5.8 Hz, 1H), 3.41-
3.37 (dd, J=10.5, 6.6 Hz, 1H), 1.68 (s, 1H), 1.64-1.56
(m, 1H), 1.39-1.21 (m, 6H), 1.16-1.02 (m, 3H), 0.90
(d, J=6.7 Hz, 3H), 0.84 (t, J=7.1 Hz, 6H); 13C NMR
(100 MHz, CDCl3) δ: 68.5 (CH2), 37.0 (CH2), 35.9 (CH),
34.5 (CH), 33.6 (CH2), 29.6 (CH2), 24.5 (CH2), 19.3
(CH3), 16.7 (CH3), 11.5 (CH3); IR (KBr) ν: 3332, 2926,
1463, 1378, 1230, 1125, 1038, 939, 769, 734 cm−1;
HRMS-ESI (m/z): [M +NH4] + calcd for C10H22O:
176.2009, found 176.2009.
(4R,8S/R)-4,8-Dimethyldecanal (1)
To a solution of compound 10 (0.500 g, 2.7 mmol) in
MeOH (15 mL) and DCM (15 mL) was inlet ozone at
−78 ℃ until the reactant solution turned blue. Then it
was added Me2S (1 mL, 13.5 mmol) at −78 ℃ and
warmed to room temperature and stirred for 5 h. The
resulting mixture was washed with water and the aque-
ous phase was extracted with DCM. The combined or-
ganic layers were washed with brine, dried over Na2SO4,
filtered, and concentrated to afford light yellow oil,
which was purified by flash column chromatography on
silica gel (petroleum ether/EtOAc: 80/1, V/V) to afford
(4R,8S/R)-4,8-dimethyldecanal as colorless oil (0.40 g,
(2R)-1-Iodo-2,6-dimethyloctane (9)
To a solution of PPh3 (5.0 g, 18.9 mmol) and imida-
zole (2.6 g, 37.8 mmol) in anhydrous dichloromethane
(60 mL) was added iodine (4.8 g, 18.9 mmol) slowly
under argon at 0 ℃. After being stirred at 0 ℃ for 30
min, a solution of (2R)-2,6-dimethyloctan-1-ol (1.00 g,
6.3 mmol) in anhydrous DCM (20 mL) was added. The
reactant solution was stirred at room temperature for 3 h,
quenched with water, evaporated under reduced pressure
to remove most of the organic solvent, diluted with wa-
ter, and extracted with Et2O. The combined organic lay-
ers were washed with brine, dried over Na2SO4, filtered,
concentrated, and purified by flash column chromatog-
raphy on silica gel (petroleum ether) to afford 9 (1.40 g,
83%) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ:
3.23 (dd, J=9.5, 4.4 Hz, 1H), 3.15 (dd, J=9.5, 6.1 Hz,
1H), 1.51-1.40 (m, 1H), 1.39-1.05 (m, 9H), 0.97 (d,
J=6.5 Hz, 3H), 0.86 (t, J=7.1 Hz, 6H); 13C NMR (100
MHz, CDCl3) δ: 36.9 (CH2), 36.7 (CH2), 34.9 (CH2),
34.4 (CH), 29.6 (CH2), 24.5 (CH2), 20.8 (CH3), 19.3
(CH3), 18.2 (CH2), 11.6 (CH3); IR (KBr) ν: 2959, 2926,
2872, 1460, 1425, 1378, 1324, 1234, 1193, 605, 586
cm−1; HRMS-EI (m/z): M+ calcd for C10H21I: 268.0688,
found 268.0690.
1
80%). H NMR (400 MHz, CDCl3) δ: 9.75 (t, J=1.80
Hz, 1H), 2.49-2.30 (m, 2H), 1.71-1.59 (m, 1H), 1.48
-1.00 (m, 11H), 0.85 (dd, J=14.1, 6.7 Hz, 9H); 13C
NMR (100 MHz, CDCl3) δ: 203.1 (CH), 41.8 (CH2),
37.1 (CH2), 36.9 (CH2), 34.5 (CH), 32.5 (CH), 29.6
(CH2), 29.0 (CH2), 24.5 (CH2), 19.5 (CH3), 19.3 (CH3),
11.5 (CH3); IR (KBr) ν: 2960, 2927, 2713, 1728, 1462,
1379, 733 cm−1; HRMS-EI (m/z): M + calcd for
C12H24O 184.1827, found 184.1824.
(R)-Methyl-5-bromo-4-methylpentanoate (11)
Valerolactone 2 (16.1 g, 0.14 mmol) was dissolved in
an acetic acid solution of HBr (33 wt%, 49 mL) and the
resulting solution was stirred at 75 ℃ for 4 h. After
cooling to room temperature, MeOH (75 mL) was added
and the reaction was stirred overnight. The reaction so-
lution was concentrated in vacuo and a saturated aque-
ous solution of NaHCO3 (80 mL) was added, the mix-
ture was extracted with Et2O and the organic layers were
combined, washed with brine, dried over MgSO4, fil-
tered and concentrated in vacuo to afford 11 (24.3 g,
83%) as a yellow oil. Known compound. Rf=0.63 (sil-
(5R)-5,9-Dimethylundec-1-ene (10)
25
ica gel, EtOAc/hexane: 1/8); b.p. 42 ℃/10 Pa; [α]D
1
To a solution of 9 (1.00 g, 3.7 mmol) and CuI (106
mg, 0.6 mmol) in anhydrous THF (30 mL) was added
allylmagnesium bromide (9.3 mL, 1.0 mol/L in ether)
slowly under argon at −78 ℃. After the addition was
complete, the reaction mixture was maintained at 0 ℃
for 2 h and quenched with saturated aqueous solution of
NH4Cl and filtered. The filtrate was diluted with water
and extracted with Et2O. The combined organic layers
were washed with brine, dried over Na2SO4, and con-
centrated to afford light yellow oil, which was purified
by flash column chromatography on silica gel (petro-
leum ether) to afford 10 (0.60 g, 88%) as a colorless oil.
1H NMR (400 MHz, CDCl3) δ: 5.88-5.75 (m, 1H),
4.97 (dd, J=29.0, 13.6 Hz, 2H), 1.94-2.14 (m, 2H),
1.48-0.98 (m, 12H), 0.86 (t, J=7.0 Hz, 9H); 13C NMR
(100 MHz, CDCl3) δ: 139.6 (CH), 114.1 (CH2), 37.5
(CH2), 37.2 (CH2), 36.5 (CH2), 34.6 (CH), 32.5 (CH),
+2.1 (c 1.1, CHCl3); H NMR (400 MHz, CDCl3) δ:
3.65 (s, 1H), 3.28-3.40 (m, 2H), 2.32 (td, J=8.2, 2.1
Hz, 2H), 1.74-1.87 (m, 2H), 1.50-1.62 (m, 1H), 1.00
(d, J=6.5 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ:
173.6, 51.5, 40.5, 34.3, 31.4, 29.7, 18.4.; IR (KBr) ν: 2957,
2876, 1740, 1459, 1437, 1380, 1329, 1234, 1199, 1117,
1
991,895 cm− . Anal. calcd for C7H13O2Br: C 40.21, H
6.27; found C 40.13, H 6.29.
(4S,8R/S)-Methyl-4,8-dimethyldecanoate (13)
Preparation of 3-methylpentylmagnesium bromide
(12): 3-Methylpentyl bromide (1.816 g, 11 mmol) was
dissolved in anhydrous THF (7 mL). To a suspension of
magnesium turnings (600 mg, 25 mmol) in anhydrous
THF (2 mL) at room temperature were added an iodine
pellet and 0.5 mL of the above-mentioned solution. Af-
ter the reaction was initiated, the residual solution was
Chin. J. Chem. 2015, 33, 627—631
© 2015 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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