IDENTIFICATION AND ELECTROPHYSIOLOGICAL STUDIES OF (4S,5S)5-HYDROXY-4-METHYL-3-HEPTANONE AND 4-METHYL-3,5HEPTANEDIONEIN MALE LUCERNE WEEVILS
C.R. Unelius,1,3* K.-C. Park,1 M. McNeill,2 S. L. Wee,1,4 B. Bohman,3,5& D.M.
Suckling1
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The New Zealand Institute for Plant & Food Research Limited, PB 4704,
Christchurch 8140, New Zealand
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AgResearch Limited, Lincoln, PB 4749, Christchurch 8140, New Zealand
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School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden
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Present address: School of Environmental and Natural Resource Sciences, Faculty of
Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia
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Present address: Research School of Chemistry and Research School of Biology, The
Australian National University, Canberra, ACT 0200, Australia.
*
To whom correspondence should be addressed. E-mail: rikard.unelius@lnu.se.
Tel: +46-480-446271. Fax: +46-480-446262.
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SUPPLEMENTARY MATERIAL
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Chemical analyses. For all synthesized compounds, 1H-NMR and
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C-NMR
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spectra of CDCl3 solutions were recorded at 500 MHz and 125 MHz, using a Varian
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Unity spectrometer. Chemical shifts were expressed in ppm in relation to
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tetramethylsilane, multiplicity (s, singlet; d, doublet; t, triplet; q, quintet and m,
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multiplet), coupling constants (Hz) and number of protons. The starting materials
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employed were obtained from commercial suppliers and used without further
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purification. GC-MS analyses were conducted using a Varian CP-3800 gas
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chromatograph equipped with a VF-5MS column (30 m × 0.25 mm i.d. × 0.25 µm fi
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lm, Varian) and connected to an ion trap Varian Saturn 2200 MS with an electron
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impact of 70 eV and source temperature of 250 oC. Injection volume was 1 µl in
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splitless mode. The carrier gas was helium and the oven temperature was programmed
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to increase from 40 oC (5 min hold) to 250 oC with 5 oC/min. Chemical identity of
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volatiles from all treatments was confirmed by comparing the retention times and
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mass fragment patterns with synthetic compounds. For enantioselective analyses, a
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CYCLOSILcolumn (30 m × 0.25 mm i.d. × 0.25 µm film, J & W Scientific) and an
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isothermal GC column temperature of 89 °C was used. All other conditions were
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identical.
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Synthesis
of
4-methyl-3,5-heptanedione.
Synthesis
of
4-methyl-3,5-
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heptanedione was based on a modification of a literature procedure (Kalaitzakis et al.
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2006). A mixture of 3,5-heptanedione (6.0 g, 47 mmol), potassium carbonate (8.5 g,
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62 mmol) and methyl iodide (6.65 g, 46 mmol) in acetone (15 ml) was heated to a
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gentle reflux until GCMS analysis indicated that the reaction was completed (2 h).
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The mixture was cooled to room temperature and acetone (200 ml) was added
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followed by petroleum ether (100 ml). The solids were removed by filtration and the
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solvents removed in vacuo. The crude product was purified by column
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chromatography using 2% EtOAc in petroleum ether as eluant. The product was
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obtained as colorless oil (4.2 g, 64%). The product consisted of a mixture of dione
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and enol forms, the dione tautomer dominating (>10 times as abundant). GC-MS and
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NMR data corresponded to literature data. GC-MS: 142(5), 114(5), 113(8), 86(45),
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57(100) (Blight et al. 1984). 1HNMRδ: 3.68 (q, 1H, J=7.1 Hz), 2.49 (m, 4H), 1.31 (d,
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3H, J=7.1 Hz), 1.04 (t, 6H, J=7.2 Hz), 13CNMR δ: 207.9, 60.5, 35.0, 13.1, 7.8 ppm
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(Kalaitzakis et al. 2006).
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Synthesis of 5-hydroxy-4-methyl-3-heptanone. Diisopropylamine (42 ml, 0.30 mol)
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was dissolved in THF (100 ml). The stirred solution was cooled to 0°C and
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butyllithium (2.5 M in hexane, 80 ml, 0.20 mol) was added dropwise over 20 min.
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After 20 min of stirring at 0°C the temperature was lowered to -78°C and 3-pentanone
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(21.0 ml, 0.20 mol) was added dropwise over 20 min. The mixture was stirred at -(70-
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80)°C for 30 min before propanal (14.4 ml, 0.20 mmol) was added dropwise over 30
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min and the reaction mixture was kept at the same temperature for 1 h. Then NH4Cl
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(400 ml, sat., aq.) was added to the reaction mixture, which was allowed to warm to
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RT. The aqueous phase was extracted 3 times with diethyl ether and the combined
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organic phases were washed twice with brine and dried over MgSO4. Concentration in
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vacuo gave a yellow oil of 95% purity (29.13 g, 96%). The product consisted of a
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mixture of syn and anti isomers in a 3:2 ratio, the syn isomer dominating.
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NMR data corresponded with published data (Kalaitzakis et al. 2006; Heathcock et al.
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1979; Bohman et al. 2009). 1H-NMR δ: 3.82 (m, 1H, syn), 3.62 (m, 1H, anti), 2.43 -
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2.67 (m, 3H), 1.41 -1.57 (m, 2H), 1.13 (d, 3H, J=7.2 Hz), 1.06 (t, 3H, J=7.2 Hz), 0.98
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(t, 3H, J=7.4 Hz). 13C-NMR syn δ: 217.2, 72.8, 49.5, 35.3, 27.1, 10.6, 10.1, 7.8 ppm;
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anti δ: 217.1, 75.2, 50.8, 36.3, 27.8, 14.5, 10.1, 7.8 ppm. GCMS: 126(15), 97(14),
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86(37), 70(18), 69(11), 59(16), 57(100), 55(15).
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LITERATURE CITED
Kalaitzakis D, Rozzell JD, et al. (2006). Synthesis of valuable chiral intermediates by
isolated ketoreductases: application in the synthesis of -alkyl--hydroxy
ketones and 1,3-diols. Adv Synth Catal 348(14): 1958-1969
Heathcock CH, Pirrung MC, et al. (1979). Acyclic stereoselection. 4. Assignment of
stereostructure to -hydroxycarbonyl compounds by carbon-13 nuclear
magnetic resonance. J Org Chem 44(24): 4294-4299
Bohman B, Cavonius LR, et al. (2009). Vegetables as biocatalysts in stereoselective
hydrolysis of labile organic compounds. Green Chemistry 11(11): 1900-1905
Blight MM, Pickett JA, et al. (1984). An aggregation pheromone of Sitona lineatus:
identification and initial field studies. Naturwissenschaften 71(9): 480-480
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