Fe-CATALYZED SYNTHESIS OF METHYL-(2E,4Z)-DECA-2,4-DIENOATE
1639
Scheme 1.
O
K2CO3
H2O
BaMnO4
Cl
Cl
Cl
OCH3
Cl
OH
Ph3P=CHCOOMe
2
3
4
O
n-C5H11MgBr
OCH3
Fe(acac)3, NMP
1
the coupling constants of the vinyl hydrogens, J2,3
=
1H NMR spectrum, δ, ppm: 3.78 s (3H, CH3), 6.03 d
(1H, C2H, J = 15.6 Hz), 6.38 d (1H, C5H, J = 7.3 Hz),
6.46 d.d (1H, C4H, J = 11.0, 7.3 Hz), 7.69 d.d (1H,
C3H, J = 15.6, 11.0 Hz). 13С NMR spectrum, δC, ppm:
51.71 (CH3), 124.00 (CH=), 126.36 (CH=), 127.60 (CH=),
136.84 (CH=), 166.77 (C1). Mass spectrum, m/z (Irel,
%): 146 (20) [M]+, 117 (14), 115 (43), 111 (100), 89
(17), 87 (51), 53 (7), 52 (9), 51 (68), 50 (15).
15.3–15.6 and J4,5 = 7.3 Hz, typical for the (E)- and
(Z)-configuration, respectively, as well as by the
upfield shift of the allyl carbon atom of ester 1 by
~4 ppm as compared to the (2E,4E)-analogs [20].
The advantages of the elaborated method of syn-
thesis of pheromone 1 are the use of industrially
available (Z)-isomer of 1,3-dichloropropene, a few
number of stages, high yield, and isomeric purity of
the target product as well as low cost of the Fe-
catalyst.
Methyl-(2E,4Z)-deca-2,4-dienoate (1). To a solu-
tion of 0.1 g (0.68 mmol) of methyl-(2E,4Z)-5-chloro-
penta-2,4-dienoate 2, 7 mg (0.02 mmol) Fe(acac)3 in
the mixture of 1 mL of THF and 0.6 mL of NMP in an
argon atmosphere at 0°С was slowly added 0.75 mL of
the 1 M solution of n-pentylmagnesium bromide in
THF. The reaction mixture was stirred for 0.5 h at
room temperature, treated with 10% HCl and 8 mL of
hexane, the organic layer separated, the water layer
extracted with hexane (3×5 mL). Organic extracts
were combined, washed with saturated solution of
NaHCO3, dried with MgSO4, and concentrated. The
product was purified by column chromatography
(SiO2, hexane–ethyl acetate, 9 : 1). Yield 0.097 g
(2Z)-3-Chloroprop-2-en-1-ol (4). A mixture of
2 g (0.018 mol) of (Z)-1,3-dichloropropene 3, 3.18 g
(0.023 mol) of K2CO3 in 14 mL of water was stirred at
boiling to complete conversion of 3 (5 h, GC control).
After cooling, the reaction mixture was saturated with
NaCl and extracted with ether (4×10 mL). Combined
extracts were dried over MgSO4 and the solvent was
removed at atmospheric pressure. Yield 1.31 g (79%).
1H NMR spectrum, δ, ppm: 3.60 br.s (1H, OH), 4.33
d.d (2H, CH2CH=, J = 6.2, 1.5 Hz), 5.93–6.00 m (1H,
CH2CH=), 6.13 d.t (1H, ClCH=, J = 7.3, 1.5 Hz). 13С
NMR spectrum, δC, ppm: 57.83 (CH2CH=), 119.24
(ClCH=), 130.62 (CH2CH=). Mass spectrum, m/z (Irel,
%): 92 (1) [M]+, 91 (6), 61 (3), 58 (4), 57 (100), 55 (9),
49 (4), 44 (7), 39 (11), 38 (5), 37 (4).
1
(78%). H NMR spectrum, δ, ppm: 0.89 t (3Н, С10Н3,
J = 7 Hz), 1.26–1.35 m (4Н, 2СН2), 1.39–1.45 m (2Н,
С7Н2), 2.30 q (2Н, С6Н2, J = 7.6 Hz), 3.75 s (3Н,
СН3О), 5.84–5.89 m (2Н, С2Н, С5Н), 6.12 t (1Н,
С4Н2, J = 11.5 Hz), 7.62 d.d (1Н, С3Н2, J = 15.3,
11.5 Hz). 13С NMR spectrum, δC, ppm: 13.96 (С10),
22.45 (С9), 28.20 (С6), 29.00 (С7), 31.35 (С8), 51.46
(СН3О), 120.63 (С2), 126.35 (С4), 139.75 (С3), 141.87
(С5), 167.73 (С1). Mass spectrum, m/z (Irel, %): 182
([M]+, 16), 113 (34), 111 (100), 82 (29), 81 (85), 79
(46), 67 (52), 66 (33), 55 (34), 53 (31), 41 (52).
Methyl-(2E,4Z)-5-chloropenta-2,4-dienoate (2).
A suspension of 0.174 g (1.88 mmol) of (2Z)-3-chloro-
prop-2-en-1-ol 4, 1.93 g (7.52 mmol) of BaMnO4, and
0.63 g (1.88 mmol) of methyl(triphenylphosphor-
anylidene)acetate in 8 mL of dry CH2Cl2 was vigo-
rously stirred at room temperature to complete con-
version of the substrate (20 h, GC control). The solid
phase was separated by centrifuging, the organic phase
was filtered through a layer of silica and concentrated.
The residue was separated by column chromatography
(SiO2, hexane–ethyl acetate, 93 : 7) to obtain 0.187 g
(68 %) of 2 and 0.045 g (16 %) of the (2Z,4Z)-isomer.
1Н and 13С NMR spectra were registered in CDCl3
on an AV-500 instrument [500 MHz (1H) and
125 MHz (13C)]. Chemical shifts were measured with
respect to TMS (1H) or the signal of the solvent (13C,
δC 77.0 ppm). The mass spectra were obtained on a
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 7 2017