GB2172886A - Imidazoisoindole dione herbicides - Google Patents

Abstract

Imidazoisoindole diones having the general formula I:- <IMAGE> wherein W represents CH or N; n represents zero or 1 when W is N, and represents zero when W is CH: one of X and Y represents a carbonyl group and the other represents the alkylidene group = CR1R2; R1 represents an alkyl or cycloalkyl group; R2 represents an optionally substituted alkyl, cycloalkyl, alkenyl, phenyl, halophenyl or benzyl group; or R1, R2 and the interjacent carbon atom, together represent a cycloalkyl group; A and B together represent an optionally substituted methylenedioxy group:- <IMAGE> or, when W is CH and Y represents a carbonyl group, A and B may each independently represent a hydrogen atom or an alkyl group; and R3 and R4, which may be the same or different, each independently represents a hydrogen atom or an optionally substituted alkyl or cycloalkyl group, are useful as herbicides.

Description

SPECIFICATION Heterotricyclic herbicides This invention relates to certain imidazoisoindoledione derivatives, the preparation of such compounds, herbicidal compositions containing them, and to their use in controlling undesired plant growth.

UK Patent Specification No. 1566523 and European Patent Application No. 41623 describe certain imidazoisoindole -2,5-diones, and their use as herbicides. It has now been found that useful herbicidal activity is present in certain structural isomers of such compounds, some of which bear a methylenedioxy substituent.

Accordingly, the present invention provides imidazoisoindole diones having the general formula I:

wherein W represents CH or N; n represents zero or 1 when W is N, and represents zero when W is CH; one of X and Y represents a carbonyl group and the other represents the alkylidene group =CR,R2; R represents an alkyl or cycloalkyl group;R2 represents an optionally substituted alkyl, cycloalkyl, alkenyl, phenyl, halophenyl or benzyl group; or R1, R2 and the interjacent carbon atom, together represent a cycloalkyl group; A and B together represent an optionally substituted methylenedioxy group

or, when W is CH and Y represents a carbonyl group, A and B may each independently represent a hydrogen atom, or an alkyl group; and R3 and R4, which may be the same or different, each independently represents a hydrogen atom or an optionally substituted alkyl or cycloalkyl group.

When any of the above substituents represents or contains an alkyl or alkenyl substituent group, this may be linear or branched and may contain up to 10, preferably up to 6, carbon atoms, suitable examples being methyl, ethyl and propyl, and in the case of an alkyl group may also be substituted by a halogen, especially chlorine, atom or an alkoxy group such as a methoxy group. When they contain a cycloalkyl substituent group this may contain from 3 to 10, preferably 3 to 8, carbon atoms, and is suitably cyclopropyl. When any of the foregoing substituents are designated as being optionally substituted, the substituent groups which are optionally present may be any of those customarily employed in the development of pesticidal compounds, and/or the modification of such compounds to influence their structure/activity, persistence, penetration or other property.Specific examples of such substituents include halogen, especially fluorine, chlorine or bromine, atoms, and nitro, cyano, hydroxyl, alkyl, haloalkyl, and alkoxy groups; in the case of halogen substituted alkyl groups, a particular preferred example is trifluoromethyl.

Preferred compounds are those wherein W represents a CH group; X represents an alkylidene group of formula =CR1R2 wherein each of R1 and R2 independently represents an alkyl group of 1-6 carbon atoms, especially methyl, ethyl or propyl, and in particular wherein R1 represents methyl and R2 represents isopropyl; A and B together represent a methylenedioxy group of formula -O-CH2-O-, or one of A and B represents a hydrogen atom and the other represents a hydrogen atom or an alkyl group of 1-6 carbon atoms, especially a methyl group.

The invention also provides a process for the preparation of imidazoisoindole diones as defined above which comprises dehydrative cyclisation of an imidazo acid of the formula ll:-

wherein W, n, X, Y, A and B are as defined above in respect of formula I. The desired cyclisation reaction is conveniently effected with dicyclohexylcarbodiimide, suitably in an organic solvent such as tetrahydrofuran. The temperature of this reaction may be between 0 C and 35"C, but preferably the reaction is initiated with cooling to 0 -5 C, followed by further reaction at ambient temperature (eg 15-25 C).

Those imidazo acids of formula Il in which A and B together represent an optionally substituted methylenedioxy group are themseives novel compounds having herbicidal activity, and as such form the subject of our copending application (K 1987).

The compounds of general formula I have been found to show interesting activity as herbicides. Accordingly, the invention further provides a herbicidal composition comprising a compound of formula I as defined above in association with at least one carrier, and a method of making such composition which comprises bringing a compound of formula I into association with at least one carrier.

The invention also provides the use of such a compound or composition according to the invention as a herbicide. Further, in accordance with the invention there is provided a method of combating undesired plant growth at a locus by treating the locus with a compound or composition according to the invention.

Application to the locus may be pre-emergence or post-emergence. The dosage of active ingredient used may, for example, be from 0.05 to 4kg/ha. A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated, which may for example be a plant, seed or soil, or to facilitate storage, transport or handling. A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating herbicidal compositions may be used. Preferably compositions according to the invention contain 0.5 to 95% by weight of active ingredient.

A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated, which may for example be a plant, seed or soil, or to facilitate storage, transport or handling. A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating herbicidal compositions may be used. Preferably compositions according to the invention contain 0.5 to 95% by weight of active ingredient.

Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montomorillonites and micas; calcium carbonate; calcium sulphate; ammonium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyi chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or aral iphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloro-ethane. Mixtures of different liquids are often suitable.

Agricultural compositions are often formulated and transported in a concentrated form which is subse quently diluted by the user before application. The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution. Thus preferably at least one carrier in a composition according to the invention is a surface-active agent. For example the composition may contain at least two carriers, at least one of which is a surface-active agent.

A surface-active agent may be an emulsifying agent, a dispersing agent or a wetting agent; it may be nonionic or ionic. Examples of suitable surface-active agents include the sodium or calcium salts of poly acrylic acids and lignin sulphonic acids; the condensation of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for example p-octyl phenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or suiphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sul phonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sul phate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may for example be formulated as wettable powders, dusts, gran yules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders usually contain 25, 50 or 75% w of active ingredient and usually contain in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabiliser(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 1/2-10% w of active ingredient. Gran ules are usually prepared to have a size between 10 and 100 BS mesh (1.676 -0.152 mm), and may be manufactured by agglomeration or impregnation techniques.Generally, granules will contain 1/2-75% w active ingredient and 0-10% w of additives such as stabilisers, surfactants, slow release modifiers and binding agents. The so-called "dry flowable powders" consist of relatively small granules having a relatively high concentration of active ingredient. Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors.Suspension conentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10% w of o ther additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation or as antifreeze agents for water.

Aqueous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick "mayonnaise"-like consistency.

The composition of the invention may also contain other ingredients, for example other compounds possessing herbicidal, insecticidal or fungicidal properties.

The invention is illustrated in the following Examples: Example 1 2-isopropyl-2-methyl-SH-imidazo[2, 1-alisoindole-3{2H),5-dione The starting imidazo acid was o-(5-isopropyl-5-methyl-4-oxo-2-imidazolin-2-yl) benzoic acid prepared as described in US Patent 4188487. 0.24g of this acid was dissolved in dry tetrahydrofuran (15 cc), cooled to 0-5"C and mixed with dicyclohexylcarbodiimide (0.19g). This reaction mixture was stirred for 15 min. at 0 5"C, and then overnight at room temperature. The solids were filtered off and the solvent evaporated to yield a residue which was chromatographically purified to yield the desired product as a solid, m.pt. 108 llO"C, whose structure was confirmed by n.m.r. and mass spectral analysis.

Analysis Calc. C 69.4; H 5.8; N 11.6% Found C 69.1; H 5.7; N 10.9% Example 2 2, 7-dimethyl-2-isopropyl-5H-imidazo[2, 1-a]isoindole-3{2Hl 5-dione, and the 2,8-dimeth yl isomer thereof The starting imidazo acid was 4(5)-methyl-2-(5-isopropyl-5-methyl-4-oxo-2-imidazolin-2-yl) benzoic acid (a mixture of the 4-methyl and 5-methyl isomers) prepared according to the procedure described in US Patent 4188487. 1.17g of this acid was dissolved in dry tetrahydrofuran (30cc), cooled to 0-5"C and mixed with dicyclohexylcarbodiimide (0.88g). The reaction mixture was stirred for 30 minutes at 0-5 C and then overnight at room temperature.The solids were filtered off and the solvent evaporated to yield a residue which was chromatographically purified and recrystallised to yield the desired product (as a solid mixture of the 4-methyl and 5-methyl isomers), m.pt. 128-134"C, whose structure was confirmed by n.m.r.

Analysis Calc. C 70.3; H 6.3; N 10.9% Found C 69.6; H 6.5; N 10.6% Example 3 A: 2-isopropyl-2-methyl-5H-imidazo[2, 1-al-[1,3]-dioxolo[4,5-j]isoindole-3{2H),5-dione, and B: the 3-isopro- pyl-3-methyl isomer thereof The starting imidazo acid was 4,5-methylenedioxy -2-(5-isopropyl-5-methyl-4-oxo-2-imidazolin-2-yl) benzoic acid, whose preparation is described in copending application (K 1987), Example 1. This acid (0.89) was suspended in dry tetrahydrofuran (150cc) and treated at 0-5" with dicyclohexyl carbodiimide (DCC) (0.549). The reaction mixture was stirred for 30 minutes at 0-5 C and then overnight at room temperature.

Further DCC was added (0.2g) and the reaction mixture stirred for a further 24 hours, after which the solids were filtered off and the solvent evaporated to yield a solid which was chromatographically purified to yield the desired isomeric products A and B. The former was a solid, m.pt. 144-146"C, and the latter a pale yellow oil; in each case the structure was confirmed by n.m.r. analysis.

Analysis A: Calc C 62.9; H 4.9; -N 9.8 Found C 55.5; H 4.0; N 7.3 B: Calc C 62.9; H 4.9; N 9.8 Found C 62.5; H 5.2; N 10.0 Example 4 The starting material was the imidazolin-2-yl quinoline acid whose preparation is described in our co pending application (K 1987) Example 2. A mixture of this acid (0.259) and acetic anhydride (5cc) was refluxed for one hour. The unreacted anhydride was evaporated from the resulting brown solution to yield a crude oily solid which was chromatographically purified. This product was a yellow oil, which crystallised on standing to a brittle yellow solid having no sharp m.pt. NMR analysis indicated a mixture of two regioisomers of

in one isomer having X = CO and Y = C(CH3) (isoC3H7), and the other having the positions of these groups reversed.Elemental analysis of the mixture gave: Analysis Calc C 64.1; H 4.4; N 12.5 Found C 62.1; H 4.7; N 11.6 Example 5 Herbicidal A ctivfty To evaluate their herbicidal activity, compounds according to the invention were tested using as representative range of plants: maize, Zea mays (Mz); rice, Oryza sativa (R); barnyard grass, Echinochloa crusgalli (BG); oat, Avena sativa (0); linseed, Linum usitatissimum (L); mustard, Sinapsis alba (M); sugar beet, Beta vulgaris (SB) and soya bean, Glycine max (S).

The tests fall into two categories, pre-emergence and post-emergence. The pre-emergence tests involved spraying a liquid formuiation of the compound onto the soil in which the seeds of the plant species mentioned above had recently been sown. The post-emergence tests involved two types of test, viz., soil drench and foliar spray tests. In the soil drench tests the soil in which the seedling plants of the above species were growing was drenched with a liquid formulation containing a compound of the invention, and in the foliar spray tests the seedling plants were sprayed with such a formulation.

The soil used in the tests was a prepared horticultural loam.

The formulations used in the tests were prepared from solutions of the test compounds in acetone containing 0.4% by weight of an alkylphenol/ethylene oxide condensate available under the trade mark TRITON X-155. These acetone solutions were diluted with water and the resulting formulations applied at dosage levels corresponding to 5 kg or 1 kg of active material per hectare in a volume equivalent to 600 litres per hectare in the soil spray and foliar spray test, and at a dosage of level equivalent to 10 kilograms of active material per hectare in a volume equivalent to approximately 3,000 litres per hectare in the soil drench tests.

In the pre-emergence tests untreated sown soil and in the post-emergence tests untreated soil bearing seedling plants were used as controls.

-The herbicidal effects of the test compounds were assessed visually twelve days after spraying the foliage and the soil, and thirteen days after drenching the soil and were recorded on a 0-9 scale. A rating 0 indicates growth as untreated control, a rating 9 indicates death. An increase of 1 unit on the linear scale approximates to a 10% increase in the level of effect.

The results of the tests are set out in Table 1.

TABLE 1 Compound Dos Foliar spray of Soil drench 10/kg/ha age Ex. No. Mz R BG O L M SB S kg/ha Mz R BG O L M SB S Mz R BG O L M SB S 1 6 5 7 5 5 8 7 7 5 5 4 7 6 4 8 8 7 9 9 8 7 8 7 8 8 1 4 2 7 4 3 8 7 6 8 9 8 6 4 7 8 8 2 5 6 7 4 4 8 8 7 5 4 5 7 5 4 8 8 7 8 9 8 7 8 7 8 8 1 4 4 6 5 2 7 7 5 7 9 8 6 7 7 8 8 3A 6 7 7 5 4 6 8 0 5 6 4 7 5 5 6 0 2 6 0 7 4 6 6 7 5 1 4 4 4 3 5 5 0 1 4 8 3 2 4 5 6 2 3B 5 4 4 5 4 6 7 8 2 3 7 4 0 5 5 7 0 1 3 3 4 3 4 6 7 1 2 3 3 0 2 4 6 0 4 6 7 7 6 6 7 8 7 1 6 5 6 6 6 7 7 1 0 9 8 6 0 7 8 0

Claims (13)

1. Imidazoisoindole diones having the general formula I:

wherein W represents CH or N; n represents zero or 1 when W is N, and represents zero when W is CH; one of X and Y represents a carbonyl group and the other represents the alkyiidene group = CR1R2; R1 represents an alkyl or cycloalkyl group;R2 represents an optionally substituted alkyl, cycloalkyl, alkenyl, phenyl, halophenyl or benzyl group; or R1, R2 and the interjacent carbon atom, together represent a cycloalkyl group; A and B together represent an optionally substituted methylenedioxy group:

or, when W is CH and Y represents a carbonyl group, A and B may each independently represent a hydrogen atom or an alkyl group; and R3 and R4, which may be the same or different, each independently represents a hydrogen atom or an optionally substituted alkyl or cycloalkyl group.

2. Compounds as claimed in Claim 1 wherein W represents a CH group; and X represents an alkylidene group of formula =CR1R2 wherein each of R1 and R2 independently represents an alkyl group of 1-6 carbon atoms.

3. Compounds as claimed in Claim 1 or 2 wherein A and B together represent a methylenedioxy group of formula -O-CH2-O-, or one of A and B represents a hydrogen atom and the other represents a hydrogen atom or an alkyl group of 1-6 carbon atoms.

4. Compounds as claimed in Claim 2 or 3 wherein X represents an alkylidene group of formula =C(CH3)(C3H7-iso).

5. Compounds as claimed in Claim 1 and specifically named in any one of Examples 1-4 herein.

6. Process for the preparation of a compound of the general formula I as defined in Claim 1, which comprises dehydrative cyclisation of an imidazole acid of the formula ll:

wherein W, n, X, Y, A and B are as defined in claim 1 in respect of formula I.

7. Process as claimed in Claim 6 wherein the cyclisation is effected by reaction with dicyclohexyl carbodiimide in the presence of an organic solvent.

8. Process as claimed in Claim 6 carried out substantially as hereinbefore described with particular reference to Examples 1-3.

9. Compounds as defined in Claim 1 whenever prepared by a process as claimed in Claim 6, 7 or 8.

10. Herbicidal composition, which comprises a compound as claimed in any of claims 1 to 5 and 9, together with a carrier.

11. A composition as claimed in Claim 10, which comprises at least two carriers, at least one of which is a surface-active agent.

12. Method of combating undesired plant growth at a locus, which comprises treating the locus with a compound as claimed in any one of claims 1 to 5 and 9, or a composition as claimed in either of claims 10 or 11.

13. The use of a compound as claimed in any one of claims 1 to 5 and 9 as-a herbicide.