Synthesis of the Southern Corn Rootworm Pheromone
409
18
23
brine, dried (MgSO4), and concentrated under atmospheric pressure.
The residue (3.12 g) was chromatographed over SiO2 (24 g), elution
with pentane giving 1.00 g (83%) of 7 as an oil. A portion of this oil
was distilled to give an analytical sample, bp (bath temperature) 120–
sample, bp 98 ꢂC at 3 Torr; nD 1.4387; ½ꢀꢀD ꢁ1:39 (c 4.09, CHCl3),
{ref. 5: ½ꢀꢀD ꢁ1:4 (c 3.017, CHCl3)}; IR ꢂmax (film) cmꢁ1: 1720
23
(s, C=O), 1466 (m), 1360 (m), 1163 (m), 719 (w); 1H-NMR ꢁH
(400 MHz, CDCl3): 0.83 (3H, d, J ¼ 6:4 Hz, CHCH3), 0.87 (3H, t,
J ¼ 6:8 Hz, CH2CH3), 1.01–1.14 (2H, m), 1.15–1.43 (13H, m), 1.52–
1.62 (2H, t-like), 2.13 (3H, s, COCH3), 2.42 (2H, t, J ¼ 7:2 Hz,
COCH2); 13C-NMR ꢁC (100 MHz, CDCl3): 14.4, 19.6, 20.1, 23.9, 27.0,
29.2, 29.4, 29.79, 29.81, 32.4, 37.0, 39.4, 43.8, 209.1 (C=O); GC-MS
[same conditions as those for 4]: tR 13.0 min (98.7%). MS of 1 (70 eV,
EI) m=z: 212 (8) [Mþ, C14H28O], 194 (7), 169 (1), 151 (4), 123 (7), 110
(17), 96 (14), 85 (22), 71 (60), 58 (100), 43 (81). HRMS of 1 [same
conditions as those for 5]: calcd. for C14H29O [ðM þ HÞþ], 213.2213;
found, 213.2211.
23
25
130 ꢂC at 100 Torr; nD 1.4208; ½ꢀꢀD ꢁ2:02 (c 4.07, pentane); IR
ꢂ
max (film) cmꢁ1: 3078 (m, C=CH2), 1641 (m, C=C), 993 (m), 910 (s),
739 (w); 1H-NMR ꢁH (400 MHz, CDCl3): 0.85 (3H, d, J ¼ 7:2 Hz,
CHCH3), 0.88 (3H, t, J ¼ 6:8 Hz, CH2CH3), 1.05–1.15 (2H, m), 1.22–
1.45 (7H, m), 1.99–2.08 (2H, m), 4.92–5.02 (2H, m, CH=CH2), 5.77–
5.87 (1H, m, CH=CH2); 13C-NMR ꢁC (100 MHz, CDCl3): 14.4, 19.6,
20.1, 26.4, 32.4, 34.1, 36.5, 39.3, 114.0, 139.1; GC-MS [same
conditions as those for 4]: tR 4.5 min (94.1%). MS of 7 (70 eV, EI) m=z:
140 (0.4) [Mþ, C10H20], 125 (0.5), 112 (2), 97 (76), 84 (33), 69 (49),
55 (100), 43 (55).
(R)-10-Methyl-5-tridecen-2-one (8).
A solution of (Cy3P)2Ru-
Acknowledgments
(=CHPh)Cl2 (Grubbs I catalyst, 300 mg, 0.365 mmol; Aldrich), 5-
hexen-2-one (3.59 g, 36.6 mmol), and 7 (822 mg, 5.86 mmol) in dry
CH2Cl2 (8 mL) was stirred and heated under reflux for 3.5 h in an Ar
atmosphere. An additional solution of Grubbs I catalyst (150 mg,
0.182 mmol) in dry CH2Cl2 (2 mL) was added, and stirring and heating
were continued for 6 h. The mixture was left to stand for 2 d at room
temperature, before the solvent was removed, and the residue in a
small amount of hexane was chromatographed over SiO2 (40 g).
Elution with hexane gave (4R,8EZ,13R)-4,13-dimethyl-8-hexadecene
(9) and recovered 7 (140 mg total). Further elution with hexane/EtOAc
We thank Mr. M. Kimura (President, Toyo Gosei Co.,
Ltd.) for his support. Methyl (S)-3-hydroxy-2-methyl-
propanoate was kindly supplied by Mitsubishi Rayon Co.
References
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17
(15:1) gave 900 mg (73%) of 8 as an oil. Properties of 8: nD 1.4495;
25
½ꢀꢀD ꢁ1:84 (c 3.02, hexane); IR ꢂmax (film) cmꢁ1: 1720 (s, C=O),
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1641 (w, C=C), 1161 (m), 968 (m), 739 (w); 1H-NMR ꢁH (400 MHz,
CDCl3): 0.76–0.82 (6H, m, CH3 ꢃ 2), 0.95–1.07 (2H, m), 1.13–1.36
(7H, m), 1.84–1.97 (2H, m), 2.06–2.08 (3H, m, COCH3), 2.15–2.28
(2H, m), 2.38–2.48 (2H, m, COCH2), 5.19–5.41 (2H, m, CH=CH);
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27.5, 29.9, 32.3, 32.4, 32.8, 36.5, 36.6, 39.3, 43.58, 43.61, 127.4, 128.0,
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tR 12.78 min [31.0%, (Z)-isomer], 12.84 min [65.8%, (E)-isomer]. MS
of (E)-8 (70 eV, EI) m=z: 210 (1) [Mþ, C14H26O], 192 (1), 167 (2), 149
(9), 139 (2), 123 (9), 110 (20), 97 (28), 84 (17), 69 (18), 55 (25), 43
(100). MS of (Z)-8 was indistinguishable from that of (E)-8. HRMS of
8 [same conditions as those for 5]: calcd. for C14H27O [ðM þ HÞþ],
211.2056; found, 211.2054.
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(R)-10-Methyl-2-tridecanone (1). 10% Palladium on charcoal
(170 mg) was added to a solution of 8 (320 mg, 1.52 mmol) in EtOAc
(10 mL). The suspension was stirred in an H2 atmosphere (balloon) for
5.5 h at room temperature. The mixture was filtered through Celite, and
the catalyst and Celite were washed with Et2O. The filtrate was
concentrated in vacuo, and the residue (455 mg) was chromatographed
over SiO2 (7 g). Elution with hexane/EtOAc (50:1) gave 286 mg (89%)
of 1 as an oil. A portion of this oil was distilled to give an analytical
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