DOI 10.1007/s10600-018-2305-3
Chemistry of Natural Compounds, Vol. 54, No. 1, January, 2018
SHORT SYNTHETIC PATHWAY TO 4-METHYLNONAN-1-OL,
A RACEMIC ANALOG OF THE SEX
PHEROMONE OF Tenebrio molitor
*
R. M. Sultanov, F. Sh. Khafizov,
I. F. Khafizov, and I. V. Ozden
The sex pheromone of Tenebrio molitor L. (mealworm) was identified as 4R-methylnonan-1-ol [1], which is biologically
active, and its racemic analog [2].
Known methods for synthesizing 4-methylnonan-1-ol (1) have multiple steps and in most instances use difficultly
accessible compounds as starting materials. The yields of the target product are low [1, 3, 4].
We developed an effective synthetic method for the racemic analog of 1 that was based on the recently discovered
regioselective reductive ꢀ-metalloethylation of alkenes using ethylmagnesium derivatives with tantalum complex catalysts [5, 6].
The reaction of hept-1-ene with EtMgCl in the presence of TaCl –(i-OPr) P catalyst [EtMgCl–hept-1-ene–TaCl -
5
3
5
(i-OPr) P, 24:20:1; TaCl -(i-OPr) P, 1:1; EtMgCl concentration 0.5 mM in THF; 20°C; 3 h] in THF at room temperature
3
5
3
formed organomagnesium compound 2. For this, a solution of EtMgCl (12 mmol) in THF (24 mL) was treated with hept-1-ene
(10 mmol, 1.4 mL), TaCl (0.2 g, 0.5 mmol), and (i-OPr) P (0.1 g, 0.5 mmol). CO was slowly passed through the resulting
5
3
2
mixture at 0°C for 3 h. The mixture was treated with HCl solution (15 mL, 10%) to afford carboxylic acid 3 (1.7 g, 97%,
–1
bp 272°C at 750 mm Hg) with IR spectrum (ꢁ, cm ): 1710; PMR spectrum (ꢂ, ppm): 0.88–0.92 (2H, m), 1.16–1.52 (10H, m),
13
1.56–1.80 (1H, m), 2.28–2.38 (2H, m), 11.40 (1H, s); C NMR spectrum (ꢂ, ppm): 14.03, 19.75, 23.19, 28.30, 31.83, 31.97,
32.27, 33.10, 37.10, 179.37), which was extracted with Et O (3 ꢃ 50 mL). The extract was dried over anhydrous MgSO and
2
4
evaporated. The residue was dissolved in anhydrous Et O (10 mL), treated under Ar with LiAlH (0.42 g, 11 mmol), refluxed
2
4
for 2 h, treated with H O (10 mL), and extracted with Et O (3 ꢃ 50 mL). The extract was dried over Na SO and evaporated
2
2
2
4
to afford 1 (1.5 g, 95%) (Scheme 1).
The structure of 1 was elucidated using IR, PMR, and C NMR spectral methods and GC-MS and comparisons with
an authentic sample [4].
13
MgCl
a
b
+
EtMgCl
R
2
1, 3
3: R = CO H
2
c
1: R = CH OH
2
i
a. TaCl (OP ) P, THF, 3 h; b. 1. CO , 2. HCl/H O; c. LiAlH /Et O
5
n
3
2
2
4
2
Scheme 1
REFERENCES
1.
2.
Y. Tanaka, H. Honda, K. Ohsawa, and I. Yamamota, J. Pestic. Sci., 14, 197 (1989).
Y. Tanaka, H. Honda, K. Ohsawa, and I. Yamamota, J. Pestic. Sci., 11, 49 (1986).
Ufa State Petroleum Technological University, 1 Kosmonavtov St., Ufa, 450062, Russia, fax: 8 (347) 243 18 13,
e-mail: sultanov55@mail.ru. Translated from Khimiya Prirodnykh Soedinenii, No. 1, January–February, 2018, p. 181. Original
article submitted March 22, 2017.
©
218
0009-3130/18/5401-0218 2018 Springer Science+Business Media, LLC
Sultanov
