Note: Descriptions are shown in the official language in which they were submitted.
~1338~7
The invention relates to an attractant for the potato moth
(Phthorimaea operculella~.
The potato moth Phthorimaea operculella ~Zeller) forms one of the
most widespread pests of potatoes in many areas of the world. A method that can
be applied for combating such types of pests is attracting male moths into a
trap by means of a pheromone produced by the female moths.
It was found by H. G. Fouda et al J. Econ. Entomol. 68, pp. 423 - 427
(1975) that a mixture of 7,11-trideca-dienyl acetates, enriched in the cis,
cis-isomer, forms a powerful and specific attractant for the male potato moth.
A short time thereafter W. L. Roelofs et al, Life Sciences 17, pp. 699 - 706
(1975) described the isolation of an attractant from the female potato moths,
which substance was identified as trans-4, cis-7-trideca-dienyl acetate, having
formula (1) of the formula sheet. These authors also state that another active
substance could be isolated but was not identified.
There has now been found a further highly active substance, i.e.
trans-4, cis-7, cis-10-trideca-trienyl acetate, having formula (2) of the formula
sheet, mixtures of which with the known compound trans-4, cis-7-trideca-dienyl
acetate show a high synergistic activity. As a result it is now possible to
prepare attractants, containing a mixture of the two substances, that show a
considerably increased activity in respect of the natural attractant (1), which
is exuded by the female moths.
According to the invention, there is provided a composition suitable
as an attractant for the potato moth (Phthorimaea operculella~, which consists
essentially of a mixture of trans-4, cis-7, cis-10-trideca-trienyl acetate and
trans-4, cis-7-trideca-dienyl acetate in a weight ratio of from about 1:10 to
about 10:1.
~urthermore, according to the invention, in a method for control
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1133827
of the potato moth ~Phthorimaea operculella) which comprises subjecting said
moth to an attractant in an amount sufficient to attract the moth, there is
provided the improvement comprising the use, as said attractant, of an effective
amount of the attractant which consists essentially of a mixture of trans-4,
cis-7, cis-10-trideca-trienyl acetate and trans-4, cis-7-trideca-dienyl acetate
in a weight ratio of from about l:lQ to about lQ:l.
Preferably, in the attractant a mixture is applied in which the
weight ratio between trans-4, cis-7, cis-10-trideca-trienyl acetate and trans-
4, cis-7-trideca-dienyl acetate amounts to of from 1:1 to 10:1.
Bringing into a form suitable for the application as an attractant
can be done in the customary way by combining the mixture of the two active sub-
stances with an inert liquid or solid carrier or substrate. Appropriate car-
riers or substrates are, e.g. paper, cellulose, rubber, porous foam plastic.
Mostly the substrates are allowed to suck up a few drops of a dilute solution
of the active mixture containing S0 to 40Q~ug of the substances and e~aporating
the solvent. The synergistic action of the mixture of the two attractants can
be shown with the aid of field tests, a number of traps, in which mixtures of
a varying composition has been provided, being set in a potato field and the
number of male moths caught in them in a certain period of time, being counted.
The results of these are shown in the table.
TABLE
The amount of active sub- Number of moths caught in
stance per trap (~g) a fortnight
t-4, c-7 t-4, cis-7, cis-10 trap trap trap total
trideca-dienyl-acetate trideca-trienyl- 1 2 3
acetate
-
200 - 123 332 307 762
160 40 6061264 931 2801
100 100 6181321 1060 2999
160 6741402 1435 3511
- 200 2751065 614 1954
_
two living females. 840 463 - 1303
-
~133827
From these test results it appears clearly that trans-4, cis-7, cis-
10-trideca-trienyl acetate per se is over twice as active as trans-4, cis-7-
trideca-dienyl acetate and that mixtures of the two compounds show a still
better activity.
The method for the preparation of the compound trans-4, cis-7, cis-
10-trideca-trienyl acetate is shown schematically on the formula sheet. In
this method 2-(6-chloro-trans-4-hexenyloxy) tetrahydropyran, formula (7), is
coupled to 1, 4-heptadiyn, formula (9), in the form of a Grignard compou~d for
the formation of 2-(trans-trideca-4-enyl-7,10-diynyl-oxy)-tetrahydropyran,
formula (10). Then this compound is converted into trans-trideca-4-enyl-7,10-
diynyl acetate, formula (11), from which by selective reduction according to a
method by Bro~n et al. J. Chem. Soc. - Chem. Comm. (1973), pp. 553 and J. Org.
Chem. 38, pp. 2226 -2230 the product desired is obtained.
The 2-(6-chloro-trans-4-hexenyloxy)-tetrahydropyran can, for instance,
be prepared by firstly coupling 3-bromo-propanol-1, formula (3), to dihydro-
pyran, thus forming 2-(3-bromopropyloxy) tetrahydropyran, formula (4). Then
from this is obtained by conversion with propargylalcohol, the compound 2-(6-
hydroxy-hex-4-ynyloxy) tetrahydropyran, formula (5). Next, this compound is
reduced to 2-(6-hydroxy-trans-4-hexenyloxy) tetrahydropyran, formula (6), from
which the corresponding 6-chloro-compound is prepared in the way known in the
art.
PREPARATION EXAMPLE
The method of preparation is illustrated by means of the example
below, showing in a the preparation of compound (7), in b the preparation of
compound (9), and in c the preparation of compound (2) from compounds (7) and
(9) -
a. The preparation of 2-(6-chloro-trans-4-hexenyloxy)tetrahydropyran (7)
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~133827
70 g (0.83 mol) of dihydropyran were added to a mixture of 79 g
(0.57 mol) of 3-bromopropanol-1 and 3 drops of concentrated hydrochloric acid,
while it was stirred and cooled, and the temperature being kept at approximately
28C.
After the mixture had been stirred for a night at ambient temperature,
it was heated for another 5 hours at 25C. The yellow-orange mixture obtained
was extracted with diethyl ether and the ether extract was washed out with a
saturated NaHC03solution and thereupon with a 20% solution of sodium chloride
in water. The oil obtained after evaporation of the solvent was distilled in
vacuum and yielded 94 g (74%) of 2-(3-bromo propyloxy) tetrahydropyran; bp.
66C/0.6 mm. Into a three-necked flask of 2 liters content were brought 600 ml
of NH3 and to this were added 200 mg of Fe (NO3)3.9 H2O, while the mixture was
stirred. After a quarter of an hour 6.1 g (0.88 mol) of lithium were added in
small portions, and when the blue colour had disappeared, 24.4 g (0.44 mol) of
propargyl alcohol in the course of half an hour. After the mixture had been
stirred for another 1.5 hours, next, rather quickly a solution of 62.4 g (0.28
mol) of the above bromium compound in 250 ml of dry tetrahydrofuran were added.
The mixture was stirred for a night at ambient temperature, thereupon 600 ml of
water were added and then it was extracted with diethyl ether (5 x 100 ml).
The extract was washed with a 20% solution of NaCL, dried over MgSO4
and then distilled in vacuum: bp. 99 C/0.01 mm, yield: 45.4 g (82%). Of the
2-(6-hydroxy-hex-4-ynyloxy) tetrahydropyran obtained 24.8 g (0.125 mol) in 130
ml of dry diethyl ether were rather quickly added to a stirred suspension of
4.3 g of lithium aluminium hydride in 90 ml of dry diethyl ether under nitrogen,
cooled at -80C. After some hours the cooling bath was removed and the mixture
firstly reheated up to ambient temperature and then refluxed for 3.5 hours. The
mixture was kept for 48 hours at ambient temperature, whereupon 12 ml of ethyl-
_4_
1~3;}8;~7
acetate were added and then 250 ml of a saturated NH4Cl solution and 200 ml of
a 20% NaCl solution. Finally the mixture was extracted with diethyl ether, the
extract was washed up to neutral with a 20% NaCl solution, dried over MgSO4 and
then distilled in vacuum; bp 87 - 88 C/0.02 mm Hg, yield 19.2 g ~77%) of
compound (6).
Under nitrogen 18.5 g (92.5 mmol) of the 2-(6-hydroxy-trans-4-
hexenyloxy3-tetrahydropyran was brought in a mixture of 50 ml of dry diethyl
ether and 25 ml of hexamethyl phosphoric acid triamide (HMPT) and then at a
temperature below 0C 50 ml of a 20% solution of butyl lithium in hexane were
added so that a wine-red colour was produced.
The mixture was reheated up to ambient temperature, whereupon a
solution of 19.1 g of p-toluene sulphonyl chloride (TsCl) in 50 ml of dry
diethyl ether and 25 ml of HMPT were added in 10 minutes, the temperature being
kept below 16C. Then 13 g of dry lithium chloride were added and after the
mixture had been stirred for 20 minutes the thin sludge obtained was poured
into 230 ml of ice-water and extracted with diethyl ether (5 x 50 ml). The
extract was washed with 20% NaCl solution; dried (MgSO4) and distilled in
vacuum, the product desired being obtained, having a bp. of 84C/0.10 mm Hg.
Yield: 16 g (79.26%) of compound (7).
b. The preparation of 1.4-heptadiyn ~9)
In a three-necked flask of 1 liter content firstly ethyl magnesium
bromide was prepared, under nitrogen, from 13 g (0.54 mol) of magnesium and
53 g (0.50 mol) of ethyl bromide in 200 ml of tetrahydrofuran. Then butyn-l
is passed at a rate of approximately 100 ml/min, for 2.5 hours, the mixture
being cooled with ice water. Thereupon it was heated for another quarter of an
hour at 60C, the passing into of nitrogen being continued. The mixture
obtained, containing butyn-l-ylmagnesium bromide, having formula (8) of the
-5-
113382'7
formula sheet was decanted in a second three-necked flask, and under nitrogen
firstly 2 g of freshly dried CuCl and then rather quickly 45 g ~0.38 mol) of
freshly distilled 3-bromo-propyn-1 were added to it. After it had been stirred
for a night, the mixture was poured into water in which 40 g of NH4Cl and 5 g
of KCN had been dissolved. The whole was extracted with diethyl ether (5 x 50
ml), the extract was washed to neutral with a 20% NaCl solution, dried (MgS04)
and distilled, the product desired being obtained, having a bp. of 54C/5.5 cm
mercury. Yield 22 g (63%).
c. The pre~aration of trans-4, cis-7, cis-10-trideca-trienylacetate (2)
In a similar way as described under b, ethyl magnesium bromide was
prepared from 4.4 g (40 mmol) of ethyl bromide and 1.0 g (40 mmol) of magnesium
in 30 ml of diethyl ether under nitrogen. To this 2.7 g (30 mmol) of 1, 4-
heptadiyn were added and the mixture was heated at 40C, gas being evolved.
After the reaction had been completed the yellow-coloured mixture
was filtered and in a nitrogen atmoshpere added to 6.6 g (30 mmol) of 2-(6-
chloro-trans-4-hexenyloxy) tetrahydropyran, in 20 ml of diethyl ether to which
also 0.5 g of CuCl had been added. A strongly exothermic reaction occurred, a
system being for~ed consisting of two layers.
After approximately 2 hours, 40 ml of dry tetrahydrofuran, were added
whereupon the mixture, while being stirred, was kept at ambient temperature for
one night. Then 50 ml of a saturated N~4Cl solution and 2 g of KCN were added
and the mixture was extracted with diethyl ether. The extract was washed with
a 20% NaCl solution to neutral, dried (MgS04) and evaporated 8.2 g of an oil
remaining.
~ ith 40 ml of glacial acetic acid and 20 ml of acetic acid anhydride
the oil obtained was converted into the acetate, which after distillation was
recovered in an amount of 1.5 g as a fraction boiling at 115 - 120C/0.03 mm
-6--
11338~7
of mercury. The reduction of the acetate was carried out with hydrogen in the
presence of a nickel catalyst. For this purpose, to 1.25 g of Ni (OCOCH3)2
.4H20 in 50 ml of ethanol under hydrogen, were added 5.0 ml of a sodium boric
hydride solutîon ~obtained from 1 g of NaBH4, 24 ml of ethanol and 1.25 ml of
2N sodium hydroxide solution and filtration of the mixture) and then another
0.7 ml of 1.2-diamino ethane. After the hydrogen absorption had been completed
(234 ml) the mixture was filtered, the filtrate diluted with 200 ml of a 20%
NaCl solution and thereupon extracted with diethyl ether. The extract was
~ashed with a 20% NaCl solution, dried over ~gS04 and evaporated, 1.1 g of a
yellow liquid being obtained. According to the NMR spectral analysis the
structure of this compound was found to agree with trans-4, cis-7, cis-10-
trideca-trienyl acetate.
1133827
FORMULA SHEET
CH3~CH2)4CH - CHCH2CH = CH~CH2)30COCH3 (1)
CH3CH2CH c CHCH2 c CHCH2CH = CH~CH2)30C0CH3 (2)
+ HocH2cH2cH2Br (3)
H
OCH2CH2CH2Br (4)
HC_CCH20H
CH2CH2CH2C-CCH2H (S) CH3CH2C_CH + CH3CH2MgBr
LiAlH4
~CH2CH2CH2CH = CHCH20H (6) CH3CH2C_CMgBr (8)
1 p-TsCI I LiCI Cu~ 1 ~ HC_CCH2Br
0 OCH2CH2CH2CH CHCH2Cl (7) + HC-CCH2C_CCH2CH3 (9)
, ~
1~1 J~ + CH3cH2MgBr
0 OCH2CH2CH2CH t CHCH2C-CCH2C_CCH2CH3 (10)
¦ HAc
Ac20
CH3COOCH2CH2CH2CH t CHCH2C_CCH2C_CCH2CH3 (11)
1 H2 / Ni - kat.
CH3COOCH2CH2CH2CH =t CHCH2CH c CHC.12CH c CHCH2CH3 (2)
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