IE43946B1 - 1,2,4-oxadizin-5-one derivatives having phytohormonal and herbicidal activity - Google Patents

Abstract

1501589 1,2,4-Oxadiazin-5-one derivatives PHILAGRO 8 Sept 1976 [11 Sept 1975] 37226/76 Heading C2C Novel 1,2,4-oxadiazin-5-one derivatives having the general formula wherein R represents a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, or a phenyl radical, and Ar represents a phenyl radical substituted by 1, 2 or 3 substituents, which-when two or three substituents are present-may be identical or different, selected from halogen atoms, the hydroxy radical, alkyl radicals containing 1 to.4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, alkylthio radicals containing 1 to 4 carbon atoms, alkylsulphinyl radicals containing 1 to 4 carbon atoms, alkylsulphonyl radicals containing 1 to 4 carbon atoms, the trifluoromethyl, trifluoromethoxy, trifluoromethylthio and carboxy radicals, alkoxycarbonyl radicals containing 2 to 5 carbon atoms, the nitro and amino radicals, alkylamino radicals containing 1 to 4 carbon atoms in the alkyl group, dialkylamino radicals containing 1 to 4 carbon atoms in each alkyl group, acylamino radicals containing 1 to 4 carbon atoms in the acyl moiety, alkoxycarbonylamino radicals containing 1 to 4 carbon atoms in the alkoxy group, the azido radical, alkanoyl radicals containing 1 to 4 carbon atoms, the sulphamoyl radical, dialkylsulphamoyl radicals containing 1 to 4 carbon atoms in each alkyl group, or the phenyl radical, or Ar represents a mononuclear aromatic heterocyclic radical with 5 atoms in the ring, the hetero atom being oxygen, sulphur or nitrogen, said heterocyclic radical being unsubstituted or substituted by a halogen atom, an alkyl radical containing 1 to 4 carbon atoms, a phenylalkyl radical containing 1 to 4 carbon atoms in the alkyl moiety, an alkoxy radical containing 1 to 4 carbon atoms or an alkylthio radical containing 1 to 4 carbon atoms, are prepared by either (a) cyclizing an amidoxime derivative of the formula wherein R 1 is (C 1 -C 4 ) alkyl, by heating in a basic medium at a temperature of from 20‹ to 70‹ C., or (b) reacting an α-aminoxy-ester of the general formula or an acid addition salt thereof, with an iminoether salt of the formula wherein HA is a molecule of hydrogen chloride or of fluoboric acid, in a basic organic solvent at a temperature of from 80‹ to 120‹ C., or (c] treating a compound of the formula wherein X is a halogen atom, with an alkali metal hydroxide in aqueous solution at a temperature of from 15‹ to 25‹ C., or (d) reacting an α-halogeno-ester of the general formula wherein Y is a halogen atom, with an amidoxime of the general formula in an aqueous organic solvent in the presence of an alkaline condensation agent at a temperature of from 20‹ to 80‹ C. The novel compounds possess phytohormonal and herbicidal properties.

Description

THIS INVENTION relates to derivatives of l,2,4-oxadiazin-5-one, to processes for their preparation and to compositions containing them.

The derivatives of 1,2,5-oxadiazin-5-one of the present invention are those compounds of the general formula: H wherein R represents a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, Or a phenyl radical, and Ar represents a phenyl radical substituted by 1, 2 or 3 substituents, which - when two or three substituents are present - may be identical or different, selected from halogen atoms, the hydroxy radical, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, alkylthio radicals containing 1 to 4 carbon atoms, alkylsulphinyl radicals containing 1 to 4 carbon atoms, alkylsulphonyl radicals containing 1 to 4 carbon atoms, the trifluoromethyl, trifluoromethoxy, trifluoromethylthio and carboxy radicals, alkoxycarbonyl radicals containing 2 to 5 carbon atoms, the nitro and amino radicals, alkylamino radicals containing 1 to 4 carbon atoms in the alkyl group, dialkylamino radicals containing .1 to 4 carbon atoms in - 2 43946 each alkyl group, acylamino radicals containing 1 to 4 carbon atoms in the acyl (preferably alkanoyl) moiety, alkoxycarbonylamino radicals containing 1 to 4 carbon atoms in the alkoxy group, the azido radical, alkanoyl radicals containing 1 to 4 carbon atoms, the sulphamoyl radical, dialkylsulphamoyl radicals containing 1 to 4 carbon atoms in each alkyl group, or the phenyl radical, or Ar represents a mononuclear aromatic heterocyclic radical with 5 atoms in the ring, the hetero atom being oxygen, sulphur or nitrogen (preferably thienyl, pyrrolyl or furyl), said heterocyclic radical being unsubstituted or substituted by a halogen atom, an alkyl radical containing 1 to 4 carbon atoms, a phenylalkyl radical containing 1 to 4 carbon atoms in the alkyl moiety, e.g. benzyl, an alkoxy radical containing 1 to 4 carbon atoms or an alkylthio radical containing 1 to 4 carbon atoms.

Preferred compounds of the invention are those l,2,4-oxadiazin-5-ones of general formula I wherein R represents a hydrogen atom or a methyl or phenyl radical, and Ar represents the phenyl radical substituted by 1, 2 · or 3 substituents selected from halogen atoms and methyl, hydroxy, methoxy, methylthio, methylsulphonyl, trifluoromethyl, trifluoromethylthio, nitro, methylamino, dimethylamino, sulphamoyl and dimethylsulphamoyl radicals, or Ar represents a mononuclear aromatic heterocyclic radical - 3 4 3 9 4 0 with 5 atoms in the ring, the hetero atom being an oxygen, sulphur or nitrogen atom, said heterocyclic radical being unsubstituted or substituted by a halogen atom or the methyl radical.

Of outstanding importance are those 1,2,4oxadiazin-5-one derivatives of general formula I wherein Ar is a thienyl radical optionally substituted by a halogen atom or a group as hereinbefore mentioned in respect of such a heterocyclic group, for example 3-(5-chlorothien-2-yl)5,6-dihydro-4H-l,2,4-oxadiazin-5-one, 3-(thien-2-yl)-5,6dihydro-4H,l,2,4-oxadiazin-5-one, 6-methyl-3-(thien-2-yl)5.6- dihydro-4H-l,2,4-oxadiazin-5-one, 3-(thien-3-yl)-5,6dihydro-4H-l,2,4-oxadiazin-5-one, 3-(5-methylthien-2-yl)5.6- dihydro-4H-l,2,4-oxadia2in-5-one, 3-(3-methylthien-2yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5-one, 3-(3-bromothien2- yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5-one, 6-ethyl-3(thien-2-yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5-one, and 6-phenyl 3- {thien-2-yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5-one.

According to a feature of the present invention, the compounds of general formula I are prepared by the process which comprises cyclising an amidoxime derivative of the general formula: - 4 439 46 Ν - OCH - COOR.

Ar - II wherein Ar and R are as hereinbefore defined, and R^ represents an alkyl radical containing 1 to 4 carbon atoms Generally the cyclisation is carried out by heating the amidoxime derivative in a basic medium at a temperature between 20° and 70°C. It is particularly advantageous to work in an organic solvent, such'as pyridine or in an alcohol such as ethanol, in the presence of an alkali metal alkoxide such as sodium methoxide or sodium ethoxide.

The amidoxime derivatives of general formula II can be obtained in accordance with one of the following methods: (1) By the reaction of an α-halogeno-ester of the 15 general formula: Y - CH - COOR.

I 1 III (wherein R and R^ are as hereinbefore defined, and Y represents a halogen atom) with an amidoxime of the general formula: 439 46 - OH Ar - C IV wherein Ar is as hereinbefore defined. The reaction is generally carried out in an aqueous organic solvent, such as a mixture of ethanol and water or dimethylformamide and water, in the presence of an alkaline condensation agent, such as sodium hydroxide, potassium hydroxide or a tetraalkylammonium hydroxide, and at a temperature between 20 and 80°C. In certain cases, it is possible to obtain by means of this reaction the cyclised compound of general formula I directly without isolating the intermediate compound of general formula II, and this is a feature of the present invention.

The amidoximes of general formula IV can be obtained by the action of hydroxylamine on a nitrile of the general formula: Ar - CN v wherein Ar is as hereinbefore defined. The reaction is generally carried out in an aqueous organic solvent, such as aqueous ethanol, at a temperature getween 20 and 80°C. (2) By the reaction of an α-aminoxy-ester of the general formula: R I H2N -O-CH - C00R1 VI (wherein R and R^ are as hereinbefore defined) or an acid - 6 43946 addition salt, e.g. hydrochloride, thereof, with an imino-ether salt of the general formula: /NH . HA VII Ό - C2H5 wherein Ar is as hereinbefore defined and HA represents a molecule of hydrogen chloride (HCl) or of fiuoboric acid (HBF^). The reaction is generally carried out in a basic organic solvent, such as pyridine, at a temperature between 15° and 35°c.

The imino-ether salt of general formula VII can be obtained by the action of a solution of hydrogen chloride in ethanol on a nitrile of general formula V, or by the action of triethyloxonium fluoborate (Meerwein salt) on an amide of the general formula: Ar - CONHVIII wherein Ar is as hereinbefore defined. (3) By the reaction of a compound of the general formula R I {N - 0 - CH - COCI Ar - CT IX ^NH2 . HCl (wherein R and Ar are as hereinbefore defined) with an alcohol of the general formula: R1°H 43S4S wherein R^ is as hereinbefore defined. The reaction is carried out by heating the compound of general formula IX in the presence of the alcohol of general formula X at a temperature between 50°C and the boiling point of the alcohol.

According to another feature of the invention, the compounds of general formula I are prepared by the reaction of an α-aminoxy-ester of general formula VI with an imino-ether salt of general formula VII in a basic organic .0 solvent,, such as pyridine, at a temperature between 80° and 120°C According to a still further feature of the invention, the compounds of general formula I are prepared by the process which comprises treating a compound of the general formula: X - CH - Ar XI wherein R and Ar are as hereinbefore defined and X represents a halogen (preferably chlorine or bromine) atom, with an alkali metal hydroxide in an aqueous solution at a temperature between 15° and 35°C.

The compounds of general formula XI can be obtained by the action of an acid chloride of the general formula: X - CH - COCl XII - 8 43946 (wherein R and X are as hereinbefore defined) with an amidoxime of general formula IV.

The reaction is generally carried out in an organic solvent, such as dioxan or toluene, in the presence of pyridine.

The compounds of general formula I obtained by the aforedescribed processes can optionally be purified by physico-chemical methods such as crystallisation or chromatography.

The l,2,4-oxadiazin-5-one derivatives of the present invention exhibit remarkable properties which render them particularly useful in the agricultural field.

The following Examples illustrate the preparation of l,2,4-oxadiaz±n-5-one derivatives of general formula I by processes hereinbefore described.

EXAMPLE 1 A mixture of ethyl 4-chlorobenzimidate hydrochloride (47.8 g), ethyl aminqoxyacetate hydrochloride (34 g) and anhydrous pyridine (820 cc) is heated at the boiling point, whilst stirring, for 16 hours. The pyridine is then evaporated under reduced pressure (20 mmHg) and the concentrate is taken up with ethyl acetate (600 cc) and water (300 cc). The organic phase is decanted and then washed with water (3 x 100 cc). After drying over anhydrous sodium sulphate, the solvent is evaporated under reduced - 9 pressure (20 mmHg). The solid residue is taken up in diisopropyl ether (100 co) and the crystals arc filtered off. 3-(4-Chlorophenyl)-5,6-dihydro-4H-lf 2,4-oxadiazin-5one (24-1 g) is thus obtained. After recrystallisation from ethanol (7 parts by volume), the product melts at 170°C.

Ethyl 4-chlorobenzimidate hydrochloride, used as starting material, can be prepared by the method of L. Weintraub, S.R. Oles and N. Kalish, J. Org. Chem. 33, LO 7,679 (1963).

EXAMPLE 2 Following the procedure of Example 1, but starting with ethyl 2-chlorobenzimidate hydrochloride and ethyl aminoxyacetate hydrochloride, 3-(2-chlorophenyl)-5,65 dihydro-4H-l,2,4-oxadiazin-5-one, melting at 132°C, is obtained in a yield of 80%.

By proceeding as described in Example 1 but using appropriate starting materials of general formulae VI and VII there were obtained the following products having the stated melting points after recrystallisation.

EXAMPLE 3 3-(4-Hydroxyphenyl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 25l°C (yield 66%).

EXAMPLE 4 > 3-(4-Methoxyphenyl)-5,6-dihydro-4B-l,2,4oxadiazin-5-one, m.p. 212°C (yield 63%). - 10 43946 EXAMPLE 5 3-(2,4-Dichlorophenyl)-5,6-dihydro-4lX-l,2,4oxadiazin-5-one, m.p. 179°C (yield 58%).

EXAMPLE 6 3-[3-(Methylthio)phenyl]-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 128°C (yield 67%).

EXAMPLE. 7 0-Ethoxycarbonylmethyl-5-chlorothiophene-2carboxamidoxime (14.1 g) and dry sodium methoxide (2.9 g) in ethanol (140 cc) are stirred at ambient temperature for 3 hours. The ethanol is then evaporated under reduced pressure and the solid residue is taken up in distilled water (100 cc). The solution thus obtained is acidified by adding N hydrochloric acid (54 cc). The white crystals which are formed are filtered off and washed with water. After drying, 3-(5-chlorothien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one (10.7 g), melting at 210°C, is obtained.

By proceeding as described in Example 7 but using appropriate starting materials of general formula II, there were obtained the following products having the stated melting points.

EXAMPLE 8 3-(Thien-2-yl)-5,6-dihydro-4H-l,2,4-oxadiasin-5one, m.p. 180°C (yield 72%).

EXAMPLE 9 6-Methyl~3-(thien-2-yl)-5,6-dihydro-4H-l,2,411 43946 oxadiazin-5-one, m.p. 187°C (yield87%).

EXAMPLE 10 3-(Thien-3-yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5one, m.p. 183°C (yield 96%).

EXAMPLE 11 3-(Fur-2-yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5one, m.p. 186°C (yield 77%).

EXAMPLE 12 3-(5-Methylthien-2-yl)-5,6-dihydro-4H~l,2,43 oxadiazin-5-one, m.p. 215°C (yield 92%).

EXAMPLE 13 3-(N-Methylpyrrol-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. l43°C (yield 69%).

EXAMPLE 14 3-(Pyrrol-2-yl)-5,6-dihydro-4H-l,2,4-oxadiazin5-one, m.p. 261°C (yield 91%).

EXAMPLE 15 3-(3-Methylthien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 100°C (yield 89%). ι EXAMPLE 16 3-(3-Bromothien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. i27°C (yield 89%).

EXAMPLE 17 3-(4-DimethylaminophenyI)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 210°C (yield 81%). - 12 439 46 EXAMPLE 18 3-(3-Nitrophenyl)-5,6-dihydro-4H-l,2,4-oxadiazin5-one, m.p. 210°C (yield 90%).

EXAMPLE 19 3-(2-Iodophenyl)-5,6-dihydro-AH-1,2,4-oxadiazin5-one, m.p. 146°C (yield 84%).

EXAMPLE 20 3-(3-fIydroxyphenyl)-5,6-dihydro-4fi-l,2,4-oxadiazin5-one, m.p. 184°C (yield 73%).

EXAMPLE 21 3-(3-Chlorophenyl)-5,6-dihydro-4H-l,2,4-oxadiazin5-one, m.p. 130°C (yield 81%).

EXAMPLE 22 3-(4-Chloro-3-nitrophenyl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 203°C (yield 68%).

EXAMPLE 23 3-(3-Fluorophenyl)-5,6-dihydro-4H-l,2,4-oxadiazin5-one, m.p. 148°C (yield 76%).

EXAMPLE 24 ' 3-(2-Fluorophenyl)-5,6-dihydro-4H-l,2,4-oxadiazin5-one, m.p. 126°C (yield 71%).

EXAMPLE 25 3-(4-N,N-Dimethylsulphamoylphenyl)-5,6-dihydro-4Hl,2,4-oxad.iazin-5-one, m.p. 190°C (yield 81%).

EXAMPLE 26 3-(3-N,N-Dimethylsulphamoylphenyl)-5,6-d.ihydro4H-l,2,4-oxadiazin-5-one, m.p. 164°C (yield 93%).

EXAMPLE 27 3-(3-Sulphamoylphenyl)~5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 205°C (yield 64%).

EXAMPLE 28 3-[3-(Trifluoromethylthio)phenyl]~5,6-dihydro4H-1,2,4-oxadiazin~5-one, m.p. 132°C (yield 76%).

EXAMPLE 29 3-(3-Methylsulphonylphenyl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one, m.p. 203°C (yield. 97%).

EXAMPLE 30 3-(2-Bromophenyl)-5,6-dihydro-4H-l,2,4-oxadiazin5-one, m.p. 123°C (yield 77%).

EXAMPLE 31 Chloroacetyl chloride (1.13 g) is added dropwise, over the course of 10 minutes, to a solution of thiophene2-carhoxamidoxime (1.42 g) in dioxan (20 cc). The white precipitate obtained is dissolved by adding pyridine (3 cc) to the reaction mixture. After 16 hours at a temperature of about 20°C, a brown oil separates out. The solvents are evaporated at a temperature of about 20°C under reduced pressure (40 mmHg followed by 1 mmHg), and the concentrate is then taken up in water (10 cc). The precipitate obtained - 14 439 46 is filtered off and washed with water (2x5 cc). After drying, 0-chloroacetyl-thiophene-2-carboxamidoxime (1.1 g), melting at 156°C, is obtained.

O-Chloroacetyl-thiophene-2-carboxamidoxime (1 g) is dissolved in toluene (20 cc) and the solution is heated under reflux for 16 hours. After decolourising with charcoal, the solution is concentrated under reduced pressure (20 mmHg) and the crystals which are deposited are dried under reduced pressure (1 mmHg) at a temperature of about 20°C. 5-Chloromethyl~3~(thien-2-yl)-l,2,4-oxadia'c;.e (0.9 g), melting at 57°C, is thus obtained.

-Chloromethyl-3-(thien-2-yl)-1.2,4-oxadiazole (0.67 g) is dissolved in dimethylformamide (5 cc). A 2N aqueous sodium hydroxide solution (5 cc) is added to the solution obtained and the mixture is stirred for 30 minutes. It is then acidified with UN hydrochloric acid (0.9 cc) and the crystals obtained are filtered off and washed with water (4 x 10 cc). After drying, 3-(thien-2-yl)-5,6dihydro-4il-l,2,4-oxadiazin-5-one (0.46 g), melting at 180°C, is obtained.

The following Examples illustrate the preparation of a l,2,4-oxadiazolin-5-one derivative of general formula I by the reaction of compounds of general formula III and IV without separation of an intermediate amidoxime derivative of general formula II which is formed and is cyclised - 15 439-56 immediately.

EXAMPLE 32 Thiophene-2-carboxamidoxime (28.4 g) is added to a 2N ethanolic sodium hydroxide solution (200 cc), and a solution of ethyl bromobutyrate in ethanol (200 co) is then added over the course of 30 minutes. The reaction mixture is stirred for 16 hours and the alcohol is then distilled at a temperature of about 25°G under reduced pressure (20 mmHg). The residue obtained is taken up in water (200 cc) and diethyl ether (100 cc). The organic phase is decanted and washed with water (100 cc). The aqueous liquors are combined and acidified with citric acid (14 g). A precipitate is obtained, which is filtered off and washed with water (3 x 20 cc) and then dried at a temperature of about 20°C under reduced pressure (1 mmHg). 6-Ethyl-3-(thien-2-yl)-5,6-dihydro-4H-l,2,4-oxadiazin-5one (10.38 g), melting at 171°C, is thus obtained. After recrystallisation from acetonitrile, the pure product melts at 176°C.

' EXAMPLE 33 By following the procedure of Example 32 but starting with thiophene-2-carboxamidoxime (20 g) and ethyl α-bromophenylacetate (34.2 g), 6-phenyl-3-(thien-2-yl)5,6-dihydro-4H-l,2,4-oxadiazin-5-one (10.3 g), melting at 173°C after recrystallisation, is obtained. - 16 As mentioned heretofore the 1,2,4-oxadiazin-5one derivatives of general formula I possess properties useful in the agricultural field.

When they are used at doses of between 1 and 100 5 g/hl of water, they exhibit phytohormonal properties. In that case, they possess auxinic actions analogous to those of indolylacetic acid or of derivatives of the phenoxyacetic acids. They are particularly useful in assisting the setting of fruit on certain plants (tomatoes), preventing the shedding of leaves or fruit, or increasing the formation of roots.

When they are used at rates of application of between 0.5 and 10 kg/ha, the l,2,4-oxadiazin-5-one derivatives of the present invention exhibit herbicidal properties, in particular against dicotyledon plants, both in pre-emergence and in post-emergence application.

For practical'application the 1,2,4-oxadiazin-5one derivatives of general formula I are rarely employed by themselves, but instead are generally employed in association with at least one carrier and/or a surface-active agent compatible with the active material and suitable for use in . agricultural or horticultural compositions. In such compositions, which are a feature of the present invention, the content of active compound can be from 0.005 to 95% by weight according to the form of presentation.

The term carrier in the sense of the present - 17 43δ·4θ description denotes an organic or inorganic, natural or synthetic, material with which the active material is associated in order to facilitate its application to the plant, to seeds or to the soil, or to facilitate its transportation, or its handling. The carrier can be solid (e.g. clays, natural or synthetic silicates, resins, waxes and solid fertilisers) or fluid (e.g. water, alcohols, ketones, petroleum fractions, chlorinated hydrocarbons or liquefied gases).

The surface-active agent can be an emulsifying agent, a dispersing agent or wetting agent, which can be ionic or non-ionic, for example, salts of polyacrylic acids and of ligninsulphonic acids, and condensates of ethylene oxide with fatty alcohols, fatty acids or fatty amines, and especially products based on condensates of ethylene oxide such as the condensates of ethylene oxide with octylphenol or nonylphenol.

The compositions according to the invention can be prepared in the form of wettable' powders, dusting powders, granules, solutions, suspensions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.

The wettable powders are usually prepared in such a way that they contain from 20 to 95% by weight of active compound; they usually contain, in addition to a solid >5 carrier, from 0 to 5% by weight of wetting agent, from 3 to % by weight of a dispersing agent and, where necessary, from 0 to 10% by weight of one or more stabilisers and/or other adjuvants such as penetrating agents, adhesives or anti-caking agents and dyestuffs.

By way of example, the composition of a wettable powder is given below, the percentages being expressed by weight.

EXAMPLE 34 Compound of formula I 50% calcium lignosulphate (deflocculating agent) 5% isopropyl naphthalenesulphonate (wetting agent) 1% silica anti-caking agent 5% kaolin filler 39%.

The powders for dusting are usually prepared in the form of a dust concentrate having a composition similar to that of a wettable powder but without dispersing agent; they can be diluted on site by means of a supplementary amount of a solid carrier so that a composition which usually contains from 0.5 to 10% by weight of active compound is obtained.

The emulsifiable concentrates which can be applied by spraying usually contain, in addition to the solvent and, where necessary, a co-solvent, from 10 to 50% (w/v) of active compound, from 2 to 20% (w/v) of emulsifiers and from 0 to 20% (w/v) of appropriate additives, such as stabilisers, penetrating agents, corrosion inhibitors, dyestuffs and adhesives.

The suspension concentrates, which can also be applied by spraying, are prepared in such a way that a stable fluid product which does not sediment is obtained. They usually contain from 10 to 75% by weight of active compound, from 0.5 to 15% by weight of surface-active agents, from 0.1 to 10% by weight of anti-sedimentation agents such as protective colloids and thixotropic agents, from 0 to 10% by weight of appropriate additives, such as anti-foam agents, corrosion inhibitors, stabilisers, penetrating agents and adhesives and, as the carrier, water or an organic liquid in which the active material is substantially insoluble; certain organic solid materials or inorganic salts can be dissolved in the carrier to assist in preventing the sedimentation or to act as anti-freeze agents for the water.

Aqueous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or an emulsifiable concentrate according to the invention with water, also fall within the general scope of the present invention. These emulsions can be of the water-in-oil type or of the oil-in-water type and can have a thick consistency such as that of a mayonnaise.

For a so-called ultra-low volume application, entailing spraying as very fine droplets, solutions in 43046 organic solvents, which contain from 70 to 95% of active compound, are prepared.

The compositions according to the invention can contain other ingredients, for example protective colloids, adhesives or thickeners, thixotropic agents, stabilisers or sequestering agents, as well as other substances which are known to have pesticidal properties, in particular insecticides or fungicides.

A further example of an agricultural composition according to the invention is given below.

EXAMPLE 35 A condensation product (10 parts) of ethylene oxide and octylphenol, having 10 molecules of ethylene oxide per molecule of octylphenol, is added to a solution of 3-(thien-2-yl)-5,6-dihydro-l,2,4~oxadiazin-5-one (25 parts) in a mixture·(65' parts) of equal parts of toluene and acetophenone. The solution is used for agricultural purposes, after dilution with water, at the rate of 100 cc of solution per 100 litres of water.

The phytohormonal activity of the 1,2,4-oxadiazin5-one derivatives of the present invention is demonstrated in the following experiments. (1) Setting of fruit of tomatoes drop (0.05 cc) of the solution or suspension of the compound to be studied is deposited on the ovary of - 21 439 46 emasculated flowers of tomato plants. After a period of observation of 15 days, the percentage of fruit formed relative to the control is noted.

Used in this way, at a concentration of 100 mg/litre, the product of Example 8 shows a degree of setting of fruit of 100%, relative to the control (0%). The fruit formed is devoid of pips. (2) Propagation of tomato leaves The 3rd and 4th leaves are taken from tomato stems (Marmande variety) having 5 to 6 leaves. The petiole of each leaf is dipped, over a length of 2 to 3 cm, into the solution to be studied, contained in a test tube. 8 Days . after starting the experiment, the number of roots formed on the petioles of the treated leaves is counted and their aspect is observed.

Used in this way,· at a concentration of 10 mg/litre, the product of Example 8 causes the formation of 100% of rooted leaves, whilst the formation is zero in the case of the petioles of control plants. In the same way, but at a concentration of 1 mg/litre, the products of Examples 9 and 11 . cause the formation of 100% of rooted leaves. With the ' product of Example 9 the roots are short and thick; with the product of Example 11 the roots are short and thin. 43046 The herbicidal activity of the compounds of general formula I is demonstrated in the following manner: Seeds of various species, namsly wheat (Triticum sativum), lentil (Lens culinaris), radish (Raphanus sativus), sugar beet (Beta vulgaris) and slender foxtail (Alopecurus agrestis), are sown in plastic pots (180 cc capacity) containing to a height of 6 cm a mixture composed of 1/3 of clean earth, 1/3 of vegetable mould and 1/3 of river sand, at the rate of about 30 seeds per pot. For each concentration of compound, two pots of wheat and four potu of the other species are used.

For the purpose of a post-emergence treatment, the sowing is carried out in a greenhouse one week before the start of the experiment so that the small plants are at the following stage at the time of treatment: wheat and foxtail : 2 or 3 leaves lentil : 3 leaves beet and radish. : 2 well-developed cotyledon leaves.

The treatment is carried out by spraying the solution or suspension of the product, the pots being placed on a pot-turner. Each pot is given 1 cc of the solution.

The doses of the product to be studied are 1, 8 and 10 kg/ha.

In pre-emergence testing, the seeded surface of the pots is allowed to dry, then covered to a depth of 1 cm with the same earth mixture: twice a day the pots are watered by sprinkling. In post-emergence testing, the treated small plants are allowed to dry. The earth mixture is moistened by placing the base of the pots in a tray containing water.

In both cases, the pots are kept in a greenhouse (22° to 24° C, 70 to 80% relative humidity) under artificial light which provides 5,000 to 6,000 Lux at the level of the plants, for 17 consecutive hours per day. .

Three weeks after the start of the treatment, the number of plants in each pot is counted, and their height is measured.

The results are expressed in percentages relative to the control plants.

The results are summarised in the Table which follows. The doses of active compound used are in kg/hectare.

The percentage destruction of treated plants is noted. In the Table the figure O indicates that the compound is inactive the figure 100 indicates maximum activity. - 24 43346 ΓΤ σι ST Η 4> 11 Ο kO οο Η Product of Example No. Η Ο Η Η' Ο Η Η CO Η 03 Η CO Η C0 Η 03 Η 3 & 0» c c+ Γ 0 h K < Η· rt Φ Η σ 0 r cn • ID 0 H) ο ο Μ Ο Ο Ι-> ΟΟ Ο Ο Ο Ο ο ο ο ο ιη Η ο ο Wheat 60 100 ι ιοο 100 60 Ί 100 ί I οοτ ί οοτ ι_ οοτ 08 _I 100 100 Η ο kO ο ο to m ο r 3 rt H· H Ή w ο ο οοτ 0 25 100 <£> to Ο Ο ο ο Η Ο Ο Ο 10 10 Ο ο οοτ ο Radish io s w S5 o W ο ο in ιη Ο Ο ιη Ο Ο 00 to σ ο ο ο ί 20 j 100 ο ο -J Ο ο Beet j H σι tn ο ο 00 in in Ο Ο Ο Ο 85 100 ο ο ιη ιη ο in ιη ο Ο Ο Ο o’ ft & H· H ο ο ο ω Ο Ο to Ο Ο Ο ο ο ο Ο Ο ο ο Ο Wheat Ο ο 50 100 30 100 <4 4> ιη ο ΙΠ ·ί> ο ο70 100 90 100 Ο Lentil POST- Ο ο 4> ' Ο Ο cn ο ο to ο ο ο ο ο ο 90 100 Ο fO fu Qj H· to tf EMERGER ιη Ο ο to Ο ϋ to ο ο ο ο ο ο to ο ο Ο ο ο Beet o w ο ο to ο ο to Ο Ο to Ο Ο ο ο ο ο ο ο ο Foxtail - 25 439 4 6 The present invention also includes within its scope a method of treating useful plants, for example to assist the setting of fruit, to prevent the shedding of leaves or fruit or to increase the formation of roots, which comprises applying to the plant and/or its environment a composition comprising a 1,2,4-oxadiaain-5one derivative of general formula I and a.carrier therefor and/or at least one surface active agent as hereinbefore described.

A method for the control of weeds is also another aspect of the present invention, said method comprising applying to the weeds, or to a locus in which weeds are growing or are expected to grow, a composition as mentioned above for treating useful plants.

Claims (31)

1. WE CLAIM:

1. 1,2,4-Oxadiazin-5-one derivatives of the general formula: R, C) J ^Ar 5 wherein R represents a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms, or a phenyl radical, and Ar represents a phenyl radical substituted by 1, 2 or 3 substituents, which - when two or three substituents are present - may be identical or different, selected from lo halogen atoms, the hydroxy radical, alkyl radicals containing 1 to 4 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, alkylthio radicals containing 1 to 4 carbon atoms, alkylsulphinyl radicals containing 1 to 4 carbon atoms, alkylsulphonyl radicals containing 1 to 4 carbon atoms, the 15 trifluoromethyl, trifluoromethoxy, trifluoromethylthio and carboxy radicals, alkoxycarbonyl radicals containing 2 to 5 carbon atoms, the nitro and amino radicals, alkylamino radicals containing 1 to 4 carbon atoms in the alkyl group,, dialkylamino radicals containing 1 to 4 carbon atoms in each 20 alkyl group, acylamino radicals containing 1 to 4 carbon atoms in the acyl moiety, alkoxycarbonylamino radicals containing 1 to 4 carbon atoms in the alkoxy group, the azido radical, 27 43S 46 alkanoyl radicals containing 1 to 4 carbon atoms, the sulphamoyl radical, dialkylsulphamoyl radicals containing 1 to 4 carbon atoms in each alkyl group, or the phenyl radical, or Ar represents a mononuclear aromatic heterocyclic 5 radical with 5 atoms in the ring, the hetero atom being oxygen, sulphur or nitrogen, said heterocyclic radical being unsubstituted or substituted by a halogen atom, an alkyl radical containing 1 to 4 carbon atoms, a phenylalkyl radical containing 1 to 4 carbon atoms in the alkyl moiety, an alkoxy 10 radical containing 1 to 4 carbon atoms or an alkylthio radical containing 1 to 4 carbon atoms.

2. 1,2,4-Oxadiazin-5-one derivatives according to claim 1 wherein R represents a hydrogen atom or a methyl or phenyl radical, and Ar represents the phenyl radical 15 substituted by 1, 2 or 3 substituents selected from halogen atoms and methyl, hydroxy, methoxy, methylthio, methylsulphonyl, trifluoromethyl, trifluoromethylthio, nitro, methylamino, dimethylamino, sulphamoyl and dimethylsulphamoyl radicals, or Ar represents a mononuclear aromatic heterocyclic radical 20 with 5 atoms in the ring, the hetero atom being an oxygen, sulphur or nitrogen atom, said heterocyclic radical being unsubstituted or substituted by a halogen atom or the methyl radical.

3. l,2,4-Oxadiazin-5-one derivatives according to claim 1 or 2 wherein the mononuclear aromatic heterocyclic - 28 radical represented by Ar is thienyl, pyrrolyl or furyl.

4. l,2,4-Oxadiazin-5-one derivatives according to claim 1 wherein Ar represents a thienyl radical optionally substituted by a halogen atom or an alkyl, alkoxy or alkylthio radical, each such radical containing 1 to 4 carbon atoms, or a phenylalkyl radical containing 1 to 4 carbon atoms in the alkyl moiety.

5. 1,2,4-0xadiazin-5-one derivatives according to claim 1, 2, 3 or 4 wherein R represents a hydrogen atom or a methyl, ethyl or phenyl radical.

6. 3-(5-Chlorothien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one.

7. 3-(Thien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one.

8. 6-Methyl-3~(thien-2-yl)-5,6-dihydro-4H-l,2,4 oxadiazin-5-one.

9. 3-(Thien-3-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one.

10. 3-(5-Methylthien-2-yl)-5,6-dihydro-4H-1,2,4oxadiazin-5-one.

11. 3-(3-Methylthien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one.

12. 3-(3-Bromothien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one.

13. 6-Ethyl-3-(thien-2-yl)-5,6-dihydro-4H-l,2,4- 29 43946 oxadiazin—5~one. l4. 6-Phenyl-3-(thien-2-yl)-5,6-dihydro-4H-l,2,4oxadiazin-5-one.

14. 15. The l,2,4-oxadiazin-5-one derivative obtained as product in Example 1, 2 or 11.

15. 16. The l,2,4-oxadiazin-5-one derivative obtained as product in one of Examples 3 to 6, 13, 14 and 17 to 30.

16. 17. A process for the preparation of a 1,2,4oxadiazin-5-one derivative as claimed in claim 1 which comprises cyclising an amidoxime derivative of the general formula: Ar / CH - COORj {wherein R and Ar are as defined in claim 1, and R^ represents an alkyl radical containing 1 to 4 carbon atoms) by heating in a basic medium at a temperature between 20° and 70°C.

17. 18. A process for the preparation of a 1,2,4oxadiazin-5-one derivative as claimed in claim 1 which comprises reacting an α-halogeno-ester of the general formula: Y - CH - COOR. I 1 R (wherein R is as defined in claim 1, R^ is as defined in 30 10 43346 claim 17 and Y represents a halogen atom) with an amidoxime of the general formula: Ar N-OH ™2 (wherein Ar is as defined in claim 1) in an aqueous organic solvent medium in the presence of an alkaline condensation agent at a temperature between 20° and 80°C.

18. 19. A process for the oreparation of a 1,2,4oxadiazin-5-one derivative as claimed in claim 1 which comprises reacting an α-aminoxy-ester of the general formula H 2 N - O - CH - COORj. (wherein R is as defined in claim 1 and R^ is as defined in claim 17), or an acid addition salt thereof, with an iminoether salt of the general formula: Ar .HA (wherein Ar is as defined in claim 1 and HA represents, a molecule of hydrogen chloride or of fiuoboric acid) in a basic organic solvent at a temperature between 80° and 120°C.

19. 20. A process for the preparation of a 1,2,4oxadiazin-5-one derivative as claimed in claim 1 which 31 439 46 comprises treating a compound of the general formula: R (wherein R and Ar are as defined in claim 1, and X represents a halogen atom) with an alkali metal hydroxide in agueous solution at a temperature between 15° and 35°C.

20. 21. A process for the preparation of 1,2,4oxadiazin-5-one derivatives of the general formula specified in claim 1 substantially as hereinbefore described in any one of the foregoing Examples.

21. 22. l,2,4-Oxadiazin-5-one derivatives of the general formula specified in claim 1 when prepared by a process claimed in any one of claims 17 to 21.

22. 23. Phytohormonal and herbicidal compositions which comprise, as active ingredient, at least one 1,2,4oxadiazin-5-one derivative as claimed in any one of claims 1 to 16 in association with at least one carrier and/or surface-active agent compatible with the oxadiazinone derivative and suitable for use in agricultural or horticultural compositions.

23. 24- Compositions according to claim 23 which contain from 0.005 to 95% by weight of oxadiazinone derivative.

24. 25. Compositions according to claim 23 or 24 in which the surface-active agent is a non-ionic compound.

25. 26. Compositions according to claim 23, 24 or 25 in which a carrier for the oxadiazinone derivative is water.

26. 27. Compositions according to claim 23 substantially 5 as hereinbefore described with especial reference to Example 34 or 35.

27. 28. A method for the phytohormonal treatment of useful plants which comprises applying to a useful plant and/or its environment a composition as claimed in any one of claims 23 to 27.

28. 29. A method according to claim 28 in which the carrier for the oxadiazinone derivative is water and the composition contains from 1 to 100 grams of oxadiazinone derivative per hectolitre of water. 15

29. 30. A method for the control of weeds which comprises applying to the weeds, or to a locus in which weeds are growing or are expected to grow, a composition as claimed in any one of claims 23 to 27.

30.

31. A method according to claim 30 in which the 2o composition is applied to a weed-infested locus at a rate of application of oxadiazinone derivative of 0.5 to 10 kg per hectare.