CA1133827A - Attractant for the potato moth and the preparation of the former - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
As attractants for the potato moth (Phthorimaea operculella) mixtures of the novel compound trans-4, cis-7, cis-10-trideca-trienyl acetate with the known prior art compound trans-4, cis-7-trideca-dienyl acetate have been found to show a high synergistic activity.

Description

~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 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 -_ 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) ~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 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 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.

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)

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A composition suitable as an attractant for the potato moth (Phthorimaea operculella), which essentially consists 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.

2. An attractant according to claim 1, wherein the weight ratio of said trienyl acetate to said dienyl acetate is from about 1:1 to about 10:1.

3. An attractant according to claim 1 or 2 in combination with an inert solid or liquid carrier or substrate.

4. In a method for control of the potato moth (Phthorimaea operculella) which comprises subjecting said moth to an attractant in an amount sufficient to attract the moth, the improvement comprising the use, as said attractant, of an effective amount of the attractant according to claim 1.

5. A method according to claim 4, wherein said attractant is used in an insect trap which is located in an area which is to be protected against said moth.

6. A method according to claim 4, wherein said attractant is used to permeate the air in, around or over an area which is to be protected against said moth.

7. A method according to claim 4, 5 or 6 wherein the weight ratio of said trienyl acetate to said dienyl acetate is from about 1:1 to 10:1.