Insecticidal triffluormethyl alkane derivatives

5-(4-Fluoro-3-phenoxyphenyl)-2-(4-methoxyphenyl)-2-trifluoromethylpentane

1-(4-Fluoro-3-phenoxyphenyl)-4-(4-methoxyphenyl)-4-trifluoromethyl-2-pentene (15.12 g; 37.76 mmol) was hydrogenated in methanol (200 ml) with hydrogen using Raney nickel (5 g) at room temperature and under atmospheric pressure. After the calculated amount of hydrogen had been taken up, the catalyst was filtered off and the solvent removed under reduced pressure. After chromatography on silica gel using ethyl acetate/hexane as eluant, there was obtained a 10.1 g of product (=61.8% of theory).

n D 20 :1.5434.

Preparation of the Starting Material

A solution of butyllithium in hexane (1.6 molar; 30 ml) was added, dropwise, under a nitrogen atmosphere to [2-(4-fluoro-3-phenoxyphenyl)ethyl]triphenylphosphonium bromide (26.76 g; 48 mmol) in absolute tetrahydrofuran (200 ml). After stirring for two hours, 2-(4-methoxyphenyl)-2-trifluoromethylpropionaldehyde (10.13 g; 43.63 mmol) dissolve in absolute tetrahydrofuran (80 ml) was added, dropwise. The mixture was heated at reflux for 3 hours and then added to ice-water, extracted with ethyl acetate, the extract dried over sodium sulphate and evaporated. After chromatography on silica gel using hexane/ethyl acetate as eluent, there was obtained 1-(4-fluoro-3-phenoxyphenyl)-4-(4-phenoxyphenyl)-4-trifluoromethyl-2-pentene (15.2 g=80.5% of theory).

A 1.2 molar solution of diisobutylaluminium hydride in toluene (46 ml) was added, dropwise, to 2-(4-methoxyphenyl)-2-trifluoromethylpropionitrile (10.0 g; 43.6 mmol) in absolute toluene (100 ml) at a temperature of 5° to 10° C. After stirring at room temperature for 3 hours, the mixture was added to ice-water, acidified with dilute hydrochloric acid, extracted with ethyl acetate, the organic phase was washed with water and dried over sodium sulphate. There was obtained 2-(4-methoxyphenyl)-2-trifluoromethylpropionaldehyde (9.5 g=93.7% of theory).

Trimethylsilyl cyanide (65.1 ml; 423 mmol) was added at room temperature to 1-chloro-1-(4-methoxyphenyl)-1-trifluoromethylethane (77.6 g; 335.5 mmol) in methylene chloride (975 ml) followed by titanium tetrachloride (32.5 ml; 3.25 mmol). After stirring for 20 hours at room temparature, 2N sodium hydroxide was added carefully, dropwise, until the mixture was neutral and the precipitate separated over celite. The aqueous phase was extracted with ethyl acetate and the extract dried over sodium suphate. After concentrating, there was obtained 2-(4-methoxyphenyl)-2-trifluoromethylpropionitrile (71.49 g=90% of theory).

Titanium tetrachloride (42.3 ml; 42.17 mmol) was added, dropwise, at room temperature to 1-(4-methoxyphenyl)-1-trifluoromethylethanol in methylene chloride (100 ml). After stirring for 1 hour, the mixture was added to ice-water, extracted with methylene chloride, washed first with saturated sodium hydrogen carbonate solution and then with water, dried over sodium sulphate and concentrated. Following distillation in a rotary evaporator at 150° C./0.5 ml, there was obtained 1-chloro-1-(4-methoxyphenyl)-2-trifluoromethylethane (77.67 g=76.7% of theory).

1,1,1-Trifluoroacetone (60.4 ml; 675 mmol) dissolved in absolute ether (80 ml) was added, dropwise, at 5° to 10° C. to an ethereal Grignard solution (prepared from p-bromoanisole (84.17 g; 450 mmol) and magnesium (10.9 g; 450 mmol) in ether (600 ml)) and the mixture stirred at room temperature for 20 hours. It was then added to saturated ammonium chloride solution, extracted with ether and the extract washed with water, dried over sodium sulphate and concentrated. The precipitate was filtered off washed with hexane and the filtrate concentrated. 1-(4-methoxyphenyl)-1-trifluoromethylethanol (93.35 g=94.2% of theory) was obtained as a brown oil that was used without further purification. (The alcohol can also be coverted direct to the nitrile in a one-pot reaction.

[2-(4-Ethoxyphenyl)-2-trifluoromethylpropyl](4-fluoro-3-phenoxybenzyl)ether

Sodium hydride (144 mg; 6 mmol) was suspended in dimethoxyethane (16 ml) and then in turn, with stirring, there was added 2-(4-ethoxyphenyl)-2-trifluoromethyl-1-propanol (1.25 g; 5.044 mmol), a spatula of sodium iodide and 4-fluoro-3-phenoxybenzyl bromide (1.4 g; 5.04 mmol). After stirring for 5 hours at room temperature, the mixture was added to ice-water, extracted 3 times with ether and the extracts washed with water dried over sodium sulphate and evaporated. After chromatography on silica gel using a mixture of ethyl acetate and hexane, there was obtained 2.06 g of product (=91.1% of theory).

n 20 D; 1.5375.

Preparation of the Starting Material

2-(4-Ethoxyphenyl)-2-trifluoromethylpropionaldehyde (4.23 g; 17.18 mmol), prepared as described in Example 1 for 2-(4-methoxyphenyl)-2-trifluoromethylpropionaldehyde, was reduced with sodium borohydride in isopropanol (Organikum, VEB Deutscher Verlag der Wissenschaften, Berlin 1976, page 616). After working up and chromatography on silica gel using hexane/ethyl acetate, there was obtaine 2.71 g of 2-(4-ethoxyphenyl)-2-trifluoromethyl-1-propanol (=63.7% of theory).

4-(3-Phenoxyphenyl)-1-phenyl-1-trifluoromethylbutane

4-(3-Phenoxyphenyl)-1-phenyl-1-trifluoromethyl-1-butene (3.18 g; 8.6 mmol) was hydrogenated in ethanol (40 ml) with hydrogen with the addition of Raney nickel (0.4 g) at room temperature and under atmospheric pressures. After the calculated amount of hydrogen had been taken up, the catalyst was filtered off and the solvent removed under reduced pressure. After chromatography on silica gel with hexane/toluene, there remained 2.49 g of product (=78% of theory).

n 20 D: 1.5463.

Preparation of the Starting Material

A solution of butyllithium in n-hexane (8.5 ml of 1.6 molar) was added, dropwise, at room temperature and under a nitrogen atmosphere over 10 minutes to [3-(3-phenoxyphenyl)propyl]-triphenylphophonium bromide (7.67 g; 13.75 mmol) in absolute tetrahydrofuran (40 ml). After stirring for 2 hours, α,α,α-trifluoroacetophenone (2.18 g; 12.5 mmol) dissolved in absolute tetrahydrofuran (10 ml) was added dropwise. After stirring for 3 hours at room temperature, the mixture was added to ice-water, extracted with ether and the extract dried over sodium sulphate and evaporated. After chromotography on silica gel using hexane-toluene, there was obtained 4-(3-phenoxyphenyl)-1-phenyl-1-trifluoromethyl-1-butene (3.31 g=71.9% of theory).

3-Phenoxybenzyl 2-phenyl-2-trifluoromethylethyl ether

Sodium hydride (138 mg; 5.75 mmol) was suspended in dimethoxyethane (20 ml). There was then added in turn, with stirring, 2-phenyl-2-trifluoromethylethanol (1.0 g; 5.25 mmol), a spatula full of sodium iodide and 3-phenoxybenzyl bromide (1.39 g; 5.25 mmol). After stirring for 4 hours at room temperature, the mixture was added to ice-water, extracted with ether, the extract washed with water, dried over sodium sulphate and concentrated. After chromatogrpahy on silica gel using a mixture of hexane and toluene, there was obtained 1.14 g of product (=58.3% of theory).

n 20 D: 1,546.

Preparation of the Starting Material

A 20% solution of diisobutylaluminium hydride in n-hexane (53.4 ml) was added, dropwise, to ethyl α-trifluoromethylphenylacetate (2.9 g; 12.5 mmol) (T. S. Everett, S. T. Purrington, C. L. Baumgardner, J. Org. Chem. 49, 3702 (1984)) in absolute tetrahydrofuran (50 ml) at about 60° C. The mixture was then allowed to rise to room temperature and stirred for an hour at this temperature. Then at a temperature of 5°-10° C., methanol (10.5 ml) followed by 10% aqueous potassium hydroxide (5.3 ml) was added, dropwise. After 1.5 hours, the mixture was filtered and the filtrate dried over sodium sulphate which was washed with ethyl acetate and the organic phase concentrated. There was obtained 2-phenyl-2-trifluoromethylethanol (2.07 g=87.1 of theory).

In a similar way the following compounds were prepared:

The following test Examples illustrate the possible uses of the compounds of the invention that have been suitably formulated for use.

TEST EXAMPLE 1

Activity against Wingless Stages of Black Bean Aphids (Aphis fabae)

Compounds of the invention were made up as aqueous emulsions at a concentration of 0.1%. Broad bean (Vicia fabae) plants (one plant per pot) that had previously been infested with wingless stages of the black bean aphid (Aphis fabae) were sprayed until dripping wet with these preparations. After this, the treated test samples were left in the laboratory under extended daylight conditions for 48 hours. The % mortality of the larvae after 48 hours from the start of the experiment in comparison with untreated controls indicated the level of activity.

In this experiment, the compounds of the preparative Examples 1-43, 44-46, 48-51, 53, 64, 66, 67, 69-75, 77, 79, 98 and 101 showed 100% activity.

TEST EXAMPLE 2

Activity against Larvae of the Diamond-Backed Moth (Plutella xylostella).

The compounds of the invention were made up as aqueous emulsions at a concentration of 0.1%. Cabbage leaves (Brassica olearacea var. botrytis), placed in polystyrene petri dishes, were sprayed with these preparations (4 mg spray/cm 2 ). After the sprayed surface had dried, 10 young larvae of the diamond-backed moth (Plutella xylostella) were placed in each petri dish and thereby exposed to the treated food in the closed dishes for two days. The % mortality of the larvae after two days indicated the level of activity.

In this experiment, the compounds of the preparative Examples 2, 3, 4, 9, 19, 22, 24, 31-54, 56, 58-60, 62, 72-75, 79-82, 84, 87, 90, 93, 95-98, 100 and 101 showed 100% activity.

TEST EXAMPLE 3

Activity against Larvae (L3) of the Mexican Bean Beetle (Epilachna varivestis)

The compounds of the invention were made up as aqueous emulsions at a concentration of 0.1%. French bean plants (Phaseolus vulgaris) in the primary leaf stage were dipped in the preparations. For each test, two plant stems with in total four primary leaves were placed in glass vases filled with water and enclosed in plexiglass cylinders. Then five larvae of the Mexican bean beetle (Epilachna varivestis) at the third larval stage were put in the glass cylinders and kept for three days under extended daylight conditions. The % mortality of the larvae after three days indicated the level of activity.

In these experiments the compounds of Examples 2, 4, 5, 9, 11, 22, 24, 28, 33 and 62-66 showed 100% mortality.

TEST EXAMPLE 4

Activity against Larvae (L2) of the Cotton Army Worm (Spodoptera littoralis)

Compounds of the invention were made up as aqueous emulsions at a concentration of 0.1%. Leaflet pairs of beans (Vicia fabae) as well as 10 larvae (L2) of the cotton army worm (Spodoptera littoralis) per experiment were sprayed with 4 mg spray/cm 2 of these preparations in polystyrene petri dishes. The closed petri dishes were left in the laboratory under extended daylight conditions for two days. The % mortality of the larvae after two days indicated the level of activity.

In this experiment, the compounds of the preparative Examples 2, 3, 4, 9, 12, 17, 18, 21, 33-46, 49, 50, 52, 54, 58-60, 62, 64-70, 72, 75, 84, 90, 96, 98, 100 and 101 showed 100% activity.

TEST EXAMPLE 5

Ovicidal Activity against Eggs of the Cotton Army Worm (Spodoptera littoralis)

The compounds of the invention were made up as aqueous emulsions at a concentration of 0.1%. One day old eggs that had been laid on filter paper by fertilised female moths were dipped in the preparations until they were completely wet and then placed in closed petri dishes in the laboratory under extended daylight conditions for four days. The % inhibition of hatching of the eggs in comparison with untreated eggs indicates the level of activity.

In this experiment, the compounds of the preparative Examples 2, 4, 5, 64-66, 72, 73, 77, 87, 90 and 96 showed 100% activity.

TEST EXAMPLE 6

Activity against Motile Stages and Eggs of the Two Spotted Spider Mite (Tetranychus urticae)

Compounds of the invention were made up as an aqueous emulsion at a concentration of 0.1%. Dwarf bean plants (Phaseolus vulgaris) in the primary leaf stage, which had been infested with spider mites (Tetranychus urticae), were sprayed with these preparations until they were dripping wet and left in a laboratory for seven days under extende daylight conditions. After this, the % mortality of the motile stages on the one hand and the eggs on the other hand were estimated in comparison with untreated controls, using a magnifying glass.

In this experiment, the compounds of the preparative Examples 11, 12, 13, 19, 23, 24, 66, 69, 74, 75, 82, 84, 87 and 90-96 showed 100% activity.

TEST EXAMPLE 7

Activity in Prophylactic Treatment of Leaves against Brown Rice-Hoppers (Niliparvata lugens Stal)

In a heated greenhouse, rice seedlings (about 15 per pot) were grown until formation of the third leaf and then sprayed until dripping wet with an aqueous preparation containing 0.1% of active material. After drying the sprayed leaves, a transparent cylinder was placed over each pot. 30 Adult brown rice-hoppers (Niliparvata lugens) were introduced into each pot. After 2 days at 26° C. in the greenhouse, the amount of dead hoppers was determined. The activity was calculated according to Abbott in comparison with several untreated control pots.

Complete death was reached with the compounds of Examples 4, 12, 19, 22, 24, 33, 35-46, 49-55, 59-62, 64-81, 83, 84, 90, 94-96 and 114.

TEST EXAMPLE 8

Tickicidal Activity against Boophilus microplus

9 cm diameter filter papers were impregnated with 1 ml aliquots of acetone solutions of test compound at various concentrations. The papers were allowed to dry and then folded into envelopes in which cattle tick larvae, (Boophilus micoplus) were enclosed and held at 25° C. and 80% R.H. for 48 hours. The percentage mortality of tick larvae was then recorded and compared with controls.

The controls gave a mortality of less than 5% whereas compounds of Examples 2, 3, 5, 9, 10, 11, 12, 13, 22, 25, 26, 28, 32, 33, 37-46, 48, 51-55, 57, 58, 60, 62-67, 69-72, 74, 76, 77 and 79-81. caused 50% mortality at a concentration of 300 ppm or less.

TEST EXAMPLE 9

Insecticidal Activity against Lucilia sericata

1 ml aliquots of an acetone solution containing test compound at various concentrations were applied to cotton wool dental rolls 1 cm×2 cm, contained in glass vials (2 cm diameter×5 cm long). After drying, the treated materials were then impregnated with 1 ml of nutrient solution, infested with first instar larvae of sheep blowfly (Lucilia sericata), closed by a cotton wool plug and held at 25° C. for 24 hours.

For the controls the morality was <5% whereas the compounds of Examples 2, 5, 7, 9-18, 22, 23, 28, 32-35, 37-46, 51-55, 57, 58, 60-67, 69-72, 74, 76, 77 and 79-81 had an LC 50 of 100 ppm or less.

TEST EXAMPLE 10

Insecticidal Activity against Musca domestica

Aliquots of acetone solutions of test compounds at various concentrations were applied to 9 cm diameter filter papers placed in the bottom of 9 cm diameter petri dishes closed by glass lids. After evaporation of solvent, the treated surfaces, together with control treated with acetone alone, were then infested with adult houseflies, (Musca domestica) and held at 22° C. for 24 hours.

The percentage mortality of the insects was then recorded. Less than 5% mortality resulted in the control treatments whereas the compounds of Examples 2, 5, 9, 10, 11, 12, 18, 32, 39, 40, 43, 44 and 66 had an LC 50 of 400 mg/m 2 or less.

TEST EXAMPLE 11

Insecticidal Activity against Blattella germanica

Aliquots of acetone solutions of test compounds at various concentrations were applied to glass plates (10 cm×10 cm). After evaporation of solvent, the treated surfaces, together with controls treated with acetone alone, were then infested with second instar nymphs of the German cockroach, (Blattella germanica), retained on the treated surface within PTFE-coated glass rings 6 cm in diameter and held for 24 hours at 22° C. The percentage mortality of the insects was then recorded.

Less than 5% mortality resulted in the control treatments whereas the compounds of Examples 2, 3, 5, 7, 9, 11-13, 16, 17, 22, 23, 25, 27, 29, 32, 33, 37-46, 51-55, 57, 58, 60-62, 67, 69-72, 74, 76, 77 and 79-81 had an LD 50 of 100 mg/m 2 or less.