Attractant for the potato moth and the preparation of the former

As attractant for the potato moth (Phthorimaea operculella) the novel compound trans-4, cis-7,10-trideca-dienyl acetate (2) has been shown to be strongly active, both as such and, still more active, as a synergistic mixture with the known prior art compound trans-4, cis-7-trideca-dienyl acetate (1). The preparation of the compound (2) is described hereinbelow.

BACKGROUND OF THE INVENTION 
The invention relates to a method for the preparation of an attractant for 
the potato moth (Phthorimaea operculella), as well to a method for the 
preparation of the active compound trans-4, cis-7, 
cis-10-tridecatrienyl-acetate applied in this attractant. 
The potato moth Phthorimaea operculella (Zeller) forms one of the mostly 
spread pests for the potato growth 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-isomere, 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) as described hereinbelow. 
These authors also state that another active substance could be isolated 
that was not identified however. 
SUMMARY OF THE INVENTION 
Applicants have now found a further substance having major activity, i.e., 
trans-4, cis-7, cis-10-trideca-trienylacetate. 
Furthermore, it was has been found that this active substance displays a 
distinctly synergistic effect when it is combined with trans-4, 
cis-7-trideca-dienyl acetate, a substance already known. As a result it is 
possible to prepare attractants that contain a mixture of the two 
substances and that show a considerably raised activity in respect of the 
natural attractant (1), which is exuded by the female moths. 
Consequently, according to the invention, the, method for the preparation 
of an attractant for the potato moth is characterized in that a mixture of 
the compounds trans-4, cis-7, cis-10-trideca-trienyl acetate and trans-4, 
cis-7-trideca-dienyl acetate, in a weight ratio of from 1:10 to 10:1 is 
brought in a form useful for the application as a attractant. 
DETAILED DESCRIPTION OF THE INVENTION 
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 mixing the mixture of the two active 
substances with an inert liquid or solid carrier or substrate. Appropriate 
carriers 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 50 to 400 .mu.g of the 
substances and evaporating 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 
substance per trap (.mu.g) 
t-4,c-7 t-4,cis-10,cis 7 
Number of moths caught in a 
trideca-dienyl- 
trideca-trienyl- 
fortnight. 
acetate acetate. trap 1 trap 2 
trap 3 
total. 
______________________________________ 
200 -- 123 332 307 762 
160 40 606 1264 931 2801 
100 100 618 1321 1060 2999 
40 160 674 1402 1435 3511 
-- 200 275 1065 614 1954 
two living females. 
840 463 -- 1303 
______________________________________ 
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 acitivity. 
The invention comprises also a method for the preparation of the compound 
trans-4, cis-7, cis-10-trideca-trienyl acetate, which method has been 
shown schematically 
##STR1## 
In this method 2-(6-chloro-trans-4- hexenyloxy)tetrahydropyran, having 
formula (7) is coupled to 1,4-heptadiyn, having formula (9), in the form 
of a Grignard compound for the formation of 
2-(trans-trideca-4-enyl-7,10-diynyl-oxy)-tetrahydropyran, having formula 
(10). Then this compound is converted into 
trans-trideca-4-enyl-7,10-diynyl acetate, having formula (11), from which 
by selective reduction according to a method by Brown et al. 
J.Chem.Soc.-Chem.Comm. (1973), pp. 553 and J.Org.Chem. 38, pp. 226-2230 
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, having formula (3), to 
dihydropyran, thus forming 2-(3-bromopropyloxy)tetrahydropyran, having 
formula (4). Then from this is obtained by conversion with 
propargylalcohol, the compound 2-(6-hydroxy-hex-4-ynyloxy)tetrahydropyran, 
having formula (5). 
Next, this compound is reduced to 2-(6-hydroxy-trans-4-hexenyloxy) 
tetrahydropyran, having formula (6), from which the corresponding 
6-chloro-compound is prepared in the way known in the art.

PREATION EXAMPLE 
The method of preparation is elucidated by means of the non-restrictive 
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) 
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 
28.degree. C. 
After the mixture had been stirred for a night at ambient temperature, it 
was heated for another 5 hours at 25.degree. C. 
The yellow-orange mixture obtained was extracted with diethyl ether and the 
ether extract was washed out with a saturated NaHCO.sub.3 solution 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. 
66.degree. C./0.6 mm. 
Into a three-necked flask of 2 liters content were brought 600 ml of 
NH.sub.3 and to this were added 200 mg of Fe (NO.sub.3) 3.9 H.sub.2 O, 
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.times.100 ml). 
The extract was washed with a 20% solution of NaCL, dried over MgSO.sub.4 
and then distilled in vacuum; bp. 99.degree. 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 -80.degree. C. 
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 
ethylacetate were added and then 250 ml of a saturated NH.sub.4 Cl 
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 MgSO.sub.4 and 
then distilled in vacuum; bpt 87.degree.-88.degree. 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-hexenyloxy)-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 0.degree. C. 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 16.degree. C. 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.times.50 ml). The extract was washed with 20% NaCl solution; dried 
(MgSO.sub.4) and distilled in vacuum, the product desired being obtained, 
having a bp. of 84.degree. C./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-1 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 60.degree. C., the passing into of nitrogen being continued. 
The mixture obtained, containing butyn-1-ylmagnesium bromide, having 
formula (8) of the 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 NH.sub.4 Cl and 5 g of KCN had been dissolved. 
The whole was extracted with diethyl ether (5.times.50 ml), the extract 
was washed to neutral with a 20% NaCl solution, dried (MgSO.sub.4) and 
distilled, the product desired being obtained, having a bp. of 54.degree. 
C./5.5 cm mercury. Yield 22 g (63%). 
c. The preparation 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 40.degree. C., gas 
being evolved. 
After the reaction had been completed the yellow-coloured mixture was 
filtered and in a nitrogen atmosphere 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 formed 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 NH.sub.4 Cl 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 
(MgSO.sub.4) and evaporated, 8.2 g of an oil remaining. 
With 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.degree.-120.degree. C./0.03 mm 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 (OCOCH.sub.3).sub.2.4H.sub.2 O in 50 ml 
of ethanol under hydrogen, were added 5.0 ml of a sodium boric hydride 
solution (obtained from 1 g of NaBH.sub.4, 24 ml of ethanol and 1.25 ml of 
2 N 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 washed with a 20% NaCl solution, dried over MgSO.sub.4 and 
evaporated, 1.1 g of a yellow liquid being obtained. 
According the NMR spectral analysis the structure of this compound was 
found to agree with trans-4, cis-7,cis-10-trideca-trienyl acetate.