Electronic supplementary material
Synthesis of 11-meC26 (11-methylhexacosane)
All solvents and reagents were obtained from commercial vendors (Fluka, Aldrich
and Acros) and used without further purification. All reactions involving air-sensitive
reagents were performed under N2 using syringe septum cap techniques and flamedried glassware. Flash column chromatography (FCC) was performed using silica gel
(40-63 µM) from Merck or Isolute columns from Biotage. Celite (Merck) filtrations
were performed using plastic filters. Compounds were visualized by thin layer
chormatography (TLC, silica gel 60 F254 plates) using UV light, 2,4dinitrophenylhydrazine (DNP), H2SO4 or KMnO4 stain. 1H and 13C NMR spectra were
recorded on a 300 Bruker Avance instrument and CDCl3 was used as internal
reference standard ( 7.26, 77.16). GC-MS analyses were performed using an Agilent
6890N gas-chromatograph (capillary column: Agilent HP-5MS, 30 m x 25 μm x 0.25
μm; split-splitless injector; carrying gas helium) coupled with Agilent 5975 mass
selective detector (70 eV electron impact ionization) or a Shimadzu GC-17A gaschromatograph (capillary column: MDN-5S, 30 m x 25 μm x 0.25 μm, carrying gas
Helium) coupled with Shimadzu GCMS-QP 5050 (electron ionization). For examples
of use of thiophenes as 4-carbon synthons see (1-6).
1-(3-Methylthiophen-2-yl)nonan-1-ol (2)
n-Octyl magnesium bromide (17.8 ml, 2M, 35.6 mmol) was added to a solution of 3methylthiophene-2-carbaldehyde (2.96 g, 23.5 mmol) in dry THF (80 ml) at 0°C
under N2. The mixture was slowly heated and left stirring overnight at rt. Satd. NH4Cl
(aq) (5 ml) was added to the mixture and additional water was added. The mixture
was concentrated under vacuum. The remaining aqueous phase was extracted with
diethyl ether (3x), washed with brine, dried using MgSO4 and concentrated in vacuo.
FCC (heptane/diethyl ether 100:0 – 3:1) gave compound 2 as amber oil (4.88 g, 87
%). TLC (heptane/diethyl ether 2:1) Rf 0.32. 1H NMR (CDCl3) δ 0.88 (t, J=7Hz, CH3,
3H), 1.25-1.86 (br, (CH2)n, OH, 15H), 2.23 (s, CH3, 3H), 4.97 (t, J=7Hz, ArCHOH,
1H), 6.79 (d, J=5Hz, ArH, 1H), 7.15 (d, J=5Hz, ArH, 1H). 13C NMR (CDCl3) δ 13.9,
14.3, 22.8, 26.1, 29.4, 29.58, 29.64, 32.0, 39.4, 68.6, 123.1, 130.2, 133.6, 142.2. GCMS (Shimadzu) 97, 111, 124, 137, 222 [M-H2O]+.
3-Methyl-2-nonylthiophene (3)
Compound 3 was prepared using a modified method described by Lau et al. (1986).
ZnI2 (750 mg, 2.35 mmol) was added to a solution of 2 (350 mg, 1.46 mmol) in 1,2dichloroethane (50 ml) at rt, whereupon the mixture turned slightly pink. NaBH3CN
(705 mg, 11.2 mmol) was added and the mixture turned colourless. After two days
stirring at rt, the resulting white turbid mixture was filtered through Celite and the
filter cake was washed with additional dichloromethane. FCC (100 % heptane)
yielded compound 3 as a clear oil (238 mg, 73%). TLC (100 % heptane) Rf 0.64. 1H
NMR (CDCl3) δ 0.88 (t, J=7Hz, CH3, 3H), 1.27-1.64 (m, (CH2)n, 14H), 2.15 (s, CH3,
3H), 2.71 (t, J=8Hz, ArCH2, 2H), 6.77 (d, J=5Hz, ArH, 1H), 7.00 (d, J=5Hz, ArH,
1H). 13C NMR (CDCl3) δ 13.7, 14.3, 22.8, 28.0, 29.45, 29.46, 29.6, 29.7, 31.7, 32.1,
120.9, 130.0, 132.4, 139.1. GC-MS (Agilent) 111, 224 [M+].
Tridecanal (4)
Tridecanal was prepared using the method adapted from De Luca et al. (De Luca et
al. 2001).The resulting aldehyde from tridecanol (2.52 g, 12.6 mmol) was purified by
FCC (Isolute, heptane/diethyl ether 100:0 – 5:1) giving aldehyde (4) (1.17 g, 47%),
which was subsequently used for the synthesis of compound 5. 1H NMR data of 4
were in accordance with literature data (Ahmed et al. 2006).
(R/S)-1-(4-Methyl-5-nonylthiophen-2-yl)tridecan-1-ol (5)
n-Butyllithium in hexanes (0.75 ml, 1.6M, 1.2 mmol) was added to 3 (224 mg, 1.0
mmol) in dry THF (10 ml) at rt under N2. After 2 hours, tridecanal (248 mg, 1.3
mmol) was added and the mixture left stirring overnight at rt. The mixture was
quenched with satd. NH4Cl (aq) and extracted with diethyl ether (3x), washed with
brine, dried using MgSO4 and concentrated in vacuo. FCC (Isolute column,
heptane/ethyl acetate 100:0 – 80:1) gave compound 5 (423 mg, quant.). TLC
(heptane/ethyl acetate 9:1) Rf 0.28. 1H NMR (CDCl3) δ 0.90 (br t, J=7Hz, 2xCH3,
6H), 1.28-1.87 (m, (CH2)n, 36H), 2.10 (s, CH3, 3H), 2.68 (t, J=7Hz, ArCH2, 2H), 4.75
(t, J=7Hz, ArCHOH, 1H), 6.64 (s, ArH, 1H).
13
C NMR (CDCl3) δ 13.7 (CH3), 14.2
(2xCH3), 22.8 (CH2), 22.8 (CH2), 26.0 (CH2), 28.2 (CH2), 29.4 (CH2), 29.4 (CH2),
29.5 (CH2), 29.6 (CH2), 29.6 (CH2), 29.7 (CH2), 29.7 (CH2), 29.8 (CH2), 29.8 (CH2),
31.6 (CH2), 32.0 (CH2), 32.1 (CH2), 39.1 (CH2), 70.5 (CH), 126.8 (CH), 131.7 (C),
138.2 (C), 144.0 (C).
3-Methyl-2-nonyl-5-tridecylthiophene (6)
Compound 6 was prepared according to the procedure described for compound 3
starting with 5 (211 mg, 0.5 mmol) and a reaction time of 1 day. FCC (100 %
heptane) yielded compound 6 as a clear oil (137 mg, 67%). TLC (100 % heptane) Rf
0.5. 1H NMR (CDCl3) δ 0.92 (t, J=7Hz, 2xCH3, 6H), 1.30-1.41 (m, (CH2)n, 32H),
1.58-1.71 (m, 2xCH2, 4H) 2.11 (s, CH3, 3H), 2.64-2.75 (m, 2xArCH2, 4H), 6.47 (s,
ArH, 1H). 13C NMR (CDCl3) δ 13.7 (CH3), 14.3 (CH3), 22.9 (CH2), 22.9 (CH2), 28.1
(CH2), 29.4 (CH2), 29.5 (CH2), 29.5 (CH2), 29.6 (CH2), 29.6 (CH2), 29.6 (CH2), 29.7
(CH2), 29.8 (CH2), 29.9 (CH2), 29.9 (CH2), 30.2 (CH2), 31.8 (CH2), 31.9 (CH2), 32.1
(CH2), 32.1 (CH2), 77.2 (CH2), 126.9 (CH), 131.7 (C), 136.2 (C), 141.2 (C). GC-MS
(Agilent) 125, 237, 293,406 [M+].
(R/S)-11-Methylhexacosane (1) (previously described from a mixture of alkanes
isolated from natural sources (Lange et al. 1989; Gomes et al. 2008)).
A solution of 3-methyl-2-nonyl-5-tridecylthiophene (130 mg, 0.32 mmol) in dioxane
(6 ml) was purged with N2 for five minutes, whereupon Raney Ni (aq) (1.3 ml of a
50% slurry) was added. The slurry was refluxed overnight, cooled to rt and filtered
through Celite and filter cake further washed with dioxane and pentane. The clear
filtrate was concentrated in vacuo (123 mg) and checked by NMR to see
disappearance of aromatic protons. The resulting colourless wax (120 mg) in a 1:1
mixture of ethanol/heptane (12 ml) was stirred with 5% Pd/C (38 mg) under an
atmosphere of H2 at an oil bath temperature of 40ºC overnight. The mixture was
filtered through Celite and the filter cake further washed with pentane. The filtrate
was concentrated in vacuo and filtered through an Isolute column (5 g) with pentane
giving (R/S)-11-methylhexacosane as a clear oil (110 mg, 92%). 1H NMR (CDCl3) δ
0.84-0.92 (m, 3xCH3, 9H), 1.04-1.37 (m, (CH2)n, CH, 47H).
13
C NMR (CDCl3) δ
14.3 (CH3), 19.9 (CH3), 22.9 (CH2), 27.3 (CH2), 29.6 (CH2), 29.9 (CH2), 29.9 (CH2),
30.0 (CH2), 30.3 (CH2), 32.1 (CH2), 33.0 (CH), 37.3 (CH2). GC-MS (Agilent) 57, 71,
85, 99, 113, 127, 141, 168, 238/239 [M-C10H21]+ (see Fig. S1 for GC-MS and Fig. S2
for NMR spectra).
References
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muricatacin and its analogues via dihydroxylation of dienoates. J. Org. Chem.
71, 6686-6689.
De Luca, L., Giacomelli, G. & Porcheddu, A. 2001 A very mild and chemoselective
oxidation of alcohols to carbonyl compounds. Org. Lett. 3, 3041-3043.
Gomes, C. C. G., Trigo, J. R. & Eiras, A. E. 2008 Sex pheromone of the American
warble fly, Dermatobia hominis: The role of cuticular hydrocarbons. J. Chem.
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Lange, C., Basselier, J. J., Bagneres, A. G., Escoubas, P., Lemaire, M., Lenoir, A.,
Clement, J. L., Bonavita-Cougourdan, A., Trabalon, M. & Campan, M. 1989
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with
electron-impact
and
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Lau, C. K., Dufresne, C., Belanger, P. C., Piétré, S. & Scheigetz, J. 1986 Reductive
deoxygenation of aryl aldehydes and ketones and benzylic, allylic, and tertiary
alcohols by ZnI2-NaCNBH3. J. Org. Chem. 51, 3038-3043.
Figure legends
Fig. S1. Gas chromatogram and mass spectrum of synthetic 11-meC26 (11methylhexacosane).
Fig. S2. NMR spectra of synthetic 11-meC26: 1H (A) and 13C APT (B).
Fig. S3. Gas chromatograms of the cuticular hydrocarbon profile of Camponotus
herculeanus workers. Sham treated ants, i.e. supplemented only with pentane, the
solvent (A). Ants supplemented with eicosane (B); 11-methylhexacosane (C) and
3,11-dimethylheptacosane (D). The asterisk indicates the peak corresponding to the
supplemented substance in each gas-chromatogram. Numbers correspond to the
identity of peaks: 1: C22; 2: C23; 3: C24; 4: C25; 5: 11-meC25, 13-meC25; 6: C26; 7: C27
8: 15-meC27, 13-meC27; 9: 5,15-dimeC27; 10: C29; 11: 13-meC29, 15-meC29; 12: 7,13dimeC29; 13: 13-meC31,15-meC31; 14: 7,15-dimeC31; 15: 7,13-dimeC33.