USE OF BENZOXEPINE DERIVATIVES AS HERBICIDE

Description

technical field

[0001] The present invention relates to the field of herbicides useful for controlling the proliferation of unwanted plants. The invention specifically relates to the use of benzoxepin derivatives as herbicides. Previous technique

[0002] A herbicide is a chemical product in the form of an active substance or a plant protection composition effective in controlling the proliferation of unwanted plants.

[0003] A herbicide can be described as total if it destroys all types of plants, or as selective if it kills only one or more categories of unwanted plants. Similarly, it can be classified by its mode of action, for example, root penetration, systemic action, or post-emergence action.

[0004] A "root-penetrating herbicide" is a herbicide that works by being absorbed through the roots of the plant, whereas a "foliar herbicide" is absorbed by the plant through the leaves.

[0005] A "systemic herbicide" works by spreading throughout the plant via the sap, as opposed to a "contact herbicide" which only destroys the surfaces on which it is applied and is therefore in contact.

[0006] Finally, a "post-emergence herbicide" acts on the plant after the emergence of the first seedlings, while a "pre-emergence herbicide" allows action to be taken as soon as they germinate.

[0007] Currently, the herbicides used are primarily of synthetic origin, such as aromatic compounds, heterocyclic compounds, or glyphosate. However, the safety of these compounds for the environment is now clearly being questioned.

[0008] There is therefore a need for new herbicides that are effective against unwanted plants but whose side effects on the environment are significantly reduced compared to those mentioned above.

[0009] One approach to meeting this expectation is to consider the valorization of so-called naturally sourced compounds that are more easily assimilated by the environment.

[0010] Thus, lunularic acid, which is of natural origin, has for example been identified as promoting plant dormancy. Lunularia cruciata(Valio et al., Nature 1969, 223, 1176-1178) with a mechanism targeting the abscisic acid pathway in plants (Yoshikawa et al., Biosci. Biotechnol. Biochem. 2002, 66, 840-846). However, for many applications, simply stopping plant growth is insufficient. Herbicide benzoxepins are described by Macas et al.: "Synthesis of heliannane skeletons. Facile preparation of (+ / -)-heliannuol D", Tetrahedron, vol. 59, no. 10, March 3, 2003, pages 1679-1683.

[0011] The present invention therefore aims primarily to propose a new class of herbicides meeting these expectations. Description of the invention

[0012] Thus, the present invention has as its first object the use as a herbicide of at least one compound chosen from the compounds of general formula (I) corresponding to formula (Ia) below.

[0013] Against all expectations, the inventors have indeed discovered that the compounds of general formula (I), which are derivatives of benzoxepin related to radulanine, namely a compound existing naturally in liver plants, exhibit significant herbicidal activity.

[0014] While CA 1 222 755 does suggest using benzoxepinesulfonamide derivatives as herbicides, the compounds according to the invention differ from these prior derivatives by the presence of an arylalkyl group on the benzoxepine ring. As illustrated in the examples below, the presence of such a group significantly enhances the herbicidal activity of these compounds after 24 hours against unwanted plants.

[0015] According to another aspect of it, the present invention relates to a phytotoxic composition comprising, in particular as an active herbicidal substance, at least one compound selected from the compounds of general formula (I) as defined above, as well as their organic or inorganic salts and their isomers, in combination with at least one additive selected from the ancillary fertilizers, growth regulators, and herbicides.

[0016] According to another aspect, the present invention relates to a method for controlling the development and / or treating unwanted plants on the surface of a target area comprising bringing the target area into contact with an effective amount of at least one compound selected from the compounds of general formula (I) as defined above, as well as their organic or inorganic salts and their isomers, or of at least one phytotoxic composition as defined above.

[0017] Other features, variations and advantages of the use, phytotoxic composition or process according to the invention will become clearer from the detailed description and examples that follow, given by way of illustration and not limitation of the invention.

[0018] In the following text, the expressions "between ... and ...", "ranging from ... to ..." and "varying from ... to ..." are equivalent and are meant to mean that the boundaries are included, unless otherwise stated.

[0019] Unless otherwise indicated, the expression "containing / comprising one" should be understood as "containing / comprising at least one". Detailed description

[0020] As stated above, the present invention has as its primary object the use as a herbicide of at least one compound chosen from the compounds of general formula (I) corresponding to formula (Ia) below.

[0021] As representative examples of inorganic salts, alkali and alkaline earth salts can be particularly mentioned.

[0022] As a representative example of organic salts, ammonium salts can be cited in particular.

[0023] For the purposes of the invention, the term "isomers" refers to steric and optical isomers.

[0024] For the purposes of the present invention, a halogen is preferably chosen from F, Cl, Br and I, and preferably from F and Cl. In particular, compounds of formula (I) in which one or more alkyl radicals are perfluorinated radicals are considered within the scope of the present invention.

[0025] According to a preferred variant, R is an alkyl or cycloalkyl radical of 1 to 5 carbon atoms, possibly substituted by one or more halogen atoms.

[0026] According to the present invention, the compound conforms to the general formula (Ia) in which: n is an integer ranging from 1 to 6, R1, R2, and R3 independently represent a hydrogen or halogen atom, a C1 to C5 alkyl radical, or a group chosen from -OH, -COOH, -COOR'', -OR'', and -SO2. R1 represents a C1 to C5 alkyl radical, with alkyl radicals being able to be substituted by one or more halogen atoms or hydroxyl groups. R5 represents a C1 to C5 alkyl or cycloalkyl radical, possibly substituted by one or more halogen atoms. The symbol figure a single bond or a double bond in position 2, 3 or 4 of the condensed 7-membered heterocycle with at least one double bond being present, and their organic or inorganic salts and their isomers.

[0027] According to another preferred variant, the compound with general formula (I) corresponds more particularly to formula (Ib) and their organic or inorganic salts and their isomers, in which R1 < , R2 < , R and n are defined as before.

[0028] According to another preferred variant, R represents in formula (I) (Ia) or (Ib) an alkyl radical of 1 to 3 carbon atoms, and more preferably is a methyl, the alkyl radical being possibly substituted by one or more halogen atoms.

[0029] According to another preferred variant, n represents in formula (I) (Ia) or (Ib) an integer varying from 1 to 3 and more preferably is equal to 2.

[0030] According to another preferred variant, the condensed heterocycle has a single double bond at position 2, 3 or 4, and preferably at position 3.

[0031] According to another preferred variant, R 1< represents in formula (I) (Ia) or (Ib) a hydrogen atom or a -COOH group and preferably is a hydrogen atom.

[0032] According to a particular embodiment, R2 represents in formula (I)(Ia) or (Ib) a hydrogen atom or a -COOH group, or a -COOR'' group, with R'' being an alkyl radical in the C1 to C5 position, in particular with R'' being a methyl group, and preferably a hydrogen atom or a -COOH group. Advantageously, R2 represents in formula (I)(Ia) or (Ib) a -COOH group.

[0033] According to a preferred embodiment of the invention, the compound of general formula (I) is chosen from the following compounds and their organic or inorganic salts and isomers: Name Formula developed Compound A Compound H Compound C Compound D

[0034] Preferably, this compound is chosen from compounds A, H and C, as well as their salts and isomers.

[0035] In particular, the compound of formula (I) can conform to formula (Ic) as follows: and one of its organic or inorganic and isomeric salts, position 3 or 4 being substituted by a radical R, with R, R 1< and n being defined as previously. In particular, this compound can be chosen from among the compounds H and C as well as their salts and isomers.

[0036] According to a first embodiment, the compound according to the invention is implemented in an isolated form, natural or synthetic.

[0037] For the purposes of the invention, the term "isolated form" refers to the fact that the compound according to the invention is implemented in a pure form, that is to say, distinct from a mixture with other compounds, such as, for example, a plant extract containing it in association with other substances.

[0038] Thus, these compounds can be isolated from plant extracts but can also be prepared synthetically, as illustrated in the following examples. Various studies on the synthesis of such compounds are also detailed in the documents Stefinovic et al., J. Org. Chem. 1998, 63, 2808-2809; Yoshida et al., Tetrahedron 2009, 5702-2708; Yamaguchi et al., Tetrahedron 2000, 41, 4787-4790; Yamaguchi et al., J. Org. Chem. 2005, 70, 7505-7511.

[0039] According to another embodiment, the compound according to the invention is implemented in the form of a natural extract, in particular plant-based, the container.

[0040] In particular, certain compounds according to the invention can be implemented in the form of an extract of liverwort plants containing them, including, but not limited to: Radula variabilis, R. complanata, R. buccinifera, R. japonica, R. oyamensis, R. tokiensis, R. perrottetii, R. javanicawhich generally contain a mixture of these compounds and other related compounds (Asakawa et al. Phytochemistry 1978, 17, 2005-2010; Phytochemistry 1978, 17, 2115-2117; Phytochemistry 1981, 20, 858-859; Phytochemistry 1982, 21, 2481-2490; Phytochemistry 1991, 30, 235-251; Phytochemistry 1991, 30, 325-328).

[0041] The extract can be obtained by mechanical extraction, for example by pressing, or by chemical extraction, notably by leaching, maceration, or infusion. Where appropriate, the extraction may be followed by a purification step by chromatography or crystallization.

[0042] According to yet another embodiment, the compound according to the invention can be generated in situ or just before use from a precursor, for example by hydrolysis, in particular of an ester.

[0043] Of course, the different compounds of formula (I) can be used in mixture as an active herbicidal substance according to the invention.

[0044] For the purposes of the invention, the term "herbicide" means any compound or composition having the property of killing so-called undesirable plants, in particular plants.

[0045] These so-called undesirable plants are generally mosses, algae, or weeds, and include, but are not limited to, chamomile, amaranth, rock cress, mugwort, orache, cornflower, shepherd's purse, brome, cuckoo flower, thistle, goosefoot, couch grass, poppy, jimsonweed, spurge, fumitory, cleavers, galinsoga, geraniums, field gromwell, sowthistle, dead-nettle, toadstool, bindweed, chickweed, field mustard, forget-me-not, nettles, wood sorrel, pennycress, field pansy, dandelion, plantain, wild radish, ryegrass, buttercup, knotweed, groundsel, field spurge, speedwell, and cultivated vetch. For example, plants considered undesirable may be those listed in the weed guide published by the Regional Directorate of Food, Agriculture and Forestry of Nouvelle-Aquitaine.

[0046] As can be seen from the examples below, the compounds according to the invention are particularly advantageous as post-emergence herbicides.

[0047] They are particularly advantageous both as root-penetrating herbicides and as systemic herbicides.

[0048] In particular, the compounds according to the invention are used as a herbicide on plants at the seedling development stage, which is a young germinated plant with only a few leaves.

[0049] Preferably, the compound is delivered to the plant via the growing medium.

[0050] This growing substrate can be soil but also the growing media considered for hydroponic cultivation.

[0051] Advantageously, the compound is applied directly to the surface of the growing medium on which the plants to be treated are developing. As can be seen from the examples below, the plant is killed less than 96 hours, preferably less than 48 hours, and even more preferably less than 24 hours after application.

[0052] Of course, the compounds according to the invention are formulated in a manner suitable for their application at the site to be treated.

[0053] Generally speaking, this formulation dedicated to the application is a liquid and usually aqueous formulation.

[0054] This liquid formulation can be supplied as such to the user, i.e. ready for application.

[0055] It can also be a concentrated liquid formulation that must be diluted by the user just before use.

[0056] It can also be a formulation in solid form, such as granules, to be applied as such by the user or to be dispersed in an aqueous medium before use.

[0057] In general, application in a diluted form is preferred, particularly in an aqueous environment.

[0058] In the examples below, the tested compounds are implemented at a concentration ranging from 1 µg / mL to 200 µg / mL, preferably from 5µg / mL to 100 µg / mL, and even more preferably from 10 µg / mL to 100µg / mL in compound(s) according to the invention.

[0059] Of course, this effective concentration is likely to vary depending on the chemical nature of the compounds according to the invention, as well as the variety and stage of development of the unwanted plants to be treated.

[0060] It is also advantageous that the dilution be suitable for spraying.

[0061] The invention also relates to a phytotoxic composition comprising, as an active substance, at least one compound according to the invention.

[0062] This phytotoxic composition may include said compound in its pure form or in the form of a plant extract containing it.

[0063] Advantageously, the compound according to the invention is combined with at least one additive selected from among the ancillary fertilizers, growth regulators, and herbicides.

[0064] The term "annex herbicide" refers to a herbicide other than a compound of formula (I).

[0065] It may indeed be advantageous to combine a compound according to the invention with an ancillary herbicide whose effectiveness may, in particular, complement that of the compounds according to the invention. However, this ancillary herbicide is preferably a compound selected to have a reduced environmental impact.

[0066] The fertilizer is preferably a nitrogen fertilizer, which may be chosen from urea, ammonium salts, including ammonium chloride, ammonium nitrate or ammonium sulfate, leather, bone or plant powder, ammonium and potassium phosphate or mixtures thereof.

[0067] Growth regulators can be chosen from maleic hydrazide, chloromequat chloride (e.g., Cyclocel®), auxin derivatives, and mixtures thereof. Advantageously, these are growth regulators of natural origin, including salicylic acid, salicylic acid salts such as ammonium salicylate, jasmonates, auxins, gibberellins, cytokinins, lunularic acid, abscisic acid, and mixtures thereof.

[0068] The ancillary herbicides are selected from ammonium nonanoate, nonanoic acid, intermediate chain length fatty acids and their salts, urea derivatives, borax, copper sulfate, carboxylic acids and their salts, nitrogen compounds, calcium salts, and mixtures thereof.

[0069] A composition according to the invention may also contain other, more conventional ancillary additives such as surfactants, antifoaming agents, disintegrating agents, stabilizing agents, humectants, thickeners, and pH regulators, for example. The choice of these additives is most often made with regard to the intended form of the composition.

[0070] In particular, a phytotoxic composition according to the invention may be in the form of a solid composition, notably in the form of a powder or granules particularly suitable for aqueous dilution. The solid composition may also be dispersed directly onto the area to be weeded and solubilized by moistening.

[0071] A phytotoxic composition according to the invention may also be originally in the form of a liquid composition, particularly in concentrated or ready-to-use form, notably as a solution or emulsion. Similarly, the composition in concentrated liquid form may be diluted before use by adding adjuvants where appropriate.

[0072] According to another aspect, the present invention relates to a method for controlling the development and / or treating unwanted plants on the surface of a target area comprising bringing the target area into contact with an effective amount of at least one compound selected from the compounds of general formula (I), (Ia) or (Ib) as defined above, as well as their organic or inorganic salts and their isomers, or of at least one phytotoxic composition as defined above.

[0073] Advantageously, the contact is made by spraying at least one compound or at least one composition as defined above.

[0074] The following examples are presented for illustrative purposes. Example 1 Synthesis of compound A Step 1 Preparation of 5-(2-phenylethyl)-1,3-cyclohexadione

[0075]

[0076] Cinnamaldehyde is aldoled with acetone (20 equivalents) in the presence of NaOH (1 equivalent) at 0°C for 1 h to form cinnamylideneacetone. 1,3-Cyclohexadione is then obtained by condensation annealing of cinnamylideneacetone with dimethyl malonate (1.1 equivalents) in the presence of NaOMe (1.1 equivalents) under reflux of methanol for 12 h. After concentration under vacuum, the crude mixture is treated with aqueous KOH (2N) solution under reflux for 2 h, then acidified to pH 2 with 2N HCl solution and reheated under reflux for another 2 h. Finally, the ketones purified by crystallization are converted by palladium-catalyzed hydrogenation on carbon (2 mol%) in MeOH to obtain the intermediate 5-(2-phenylethyl)-1,3-cyclohexadione. Step 2 Preparation of the bicyclic dihydrooxepin intermediate

[0077]

[0078] One equivalent of Cs₂CO₃ is added to a solution of 5-(2-phenylethyl)-1,3-cyclohexadione (one equivalent) in DMSO (0.1 mol / L), and the solution is stirred at 20°C for 20 min. Next, one equivalent of 1,4-dibromo-2-methyl-2-butene in DMSO is added to the mixture at 20°C. The reaction mixture is stirred at 20°C for 12 h before being diluted with Et₂O and stopped with cold water (0°C). The organic phase is washed three times with brine (saturated NaCl solution). The aqueous phases are then extracted three times with diethyl ether. The combined organic extracts are dried over Na₂SO₄ and concentrated under reduced pressure, avoiding heating above 20°C. The residue is then purified by flash chromatography on a silica gel using a chilled column (<10°C) to provide the intermediate bicyclic dihydrooxepin as a 4:1 mixture of regioisomers methylated at positions 3 and 4, respectively. Step 3: Preparation of compound A

[0079]

[0080] The preceding compound is dihydroxylated in the presence of K₂O₂O₄·2H₂O (5 mol%) and N-methylmorpholine-N-oxide (1.3 equivalents) in a 3:1 acetone / water mixture at 0°C for 1 h. After concentration, the reaction mixture is purified twice by silica chromatography (eluent 1: petroleum ether / ethyl acetate 6:4; eluent 2: dichloromethane / methanol 98:2) to give the corresponding diol (white solid). This is then converted to the dimesylate by the action of methanesulfonic anhydride (5 equivalents) in pyridine. After 16 h at room temperature, the dimesylated product is extracted with ethyl acetate. The crude product is concentrated and diluted in DMSO, then a tetrabutylammonium fluoride solution in THF (1M, 5 equivalents) is added at 0°C and the mixture is stirred for 1 hour at room temperature (20°C).After extraction with ethyl acetate and purification by silica chromatography (eluent: petroleum ether / ethyl acetate 9:1), compound A is obtained as a colorless oil.

[0081] Compounds C, D and H are obtained in a similar manner to compound A, except that the decarboxylation of 1,3-cyclohexadione is not considered for these 3 compounds. Example 2 Synthesis of compound D Step 1 Preparation of 4-(methoxycarbonyl)-5-(2-phenylethyl)-1,3-cyclohexadione

[0082]

[0083] As before, cinnamaldehyde is aldoled with acetone (20 equivalents) in the presence of NaOH (1 equivalent) at 0°C for 1 h to form cinnamylideneacetone. 1,3-Cyclohexadione is then obtained by condensation annealing of cinnamylideneacetone with dimethyl malonate (1.1 equivalents) in the presence of NaOMe (1.1 equivalents) under reflux of methanol for 12 h. The pH is then adjusted to 5 before concentration under reduced pressure and extraction of the aqueous residue with ethyl acetate. After concentration, the solid residue is washed with diethyl ether and then recrystallized in MeOH / Et₂O to obtain the intermediate as a white solid. Finally, palladium-catalyzed hydrogenation on carbon (2 mol%) in MeOH yields the intermediate 4-(methoxycarbonyl)-5-(2-phenylethyl)-1,3-cyclohexadione. Step 2 Preparation of the bicyclic dihydrooxepin intermediate

[0084]

[0085] One equivalent of Cs₂CO₃ is added to a solution of 4-(methoxycarbonyl)-5-(2-phenylethyl)-1,3-cyclohexadione (1 equivalent) in DMSO (0.1 mol / L), and the solution is stirred at 20°C for 20 min. Next, a solution of 1,4-dibromo-2-methyl-2-butene (1.1 equivalent) in DMSO is added to the mixture at 20°C. The reaction mixture is stirred at 20°C for 12 h before being diluted with Et₂O and stopped with cold water (0°C). The organic phase is washed three times with brine (saturated NaCl solution). The aqueous phases are then extracted three times with diethyl ether. The combined organic extracts are dried over Na2SO4 and concentrated under reduced pressure, avoiding heating above 20°C. The residue is then purified by flash chromatography on silica gel using a chilled column (<10°C) to provide the intermediate bicyclic dihydrooxepin as a 1:1 mixture of ester and 4:1 methyl regioisomers. Step 3: Preparation of compound D

[0086]

[0087] The previously synthesized dihydrooxepine mixture is diluted in THF, and NaH (1.2 equivalents) is added at 0°C. After 30 minutes, a phenylselenium bromide solution (1.3 equivalents) in THF is added dropwise at 0°C, and the mixture is stirred for 1 hour. The mixture is extracted with diethyl ether, the organic phases are dried with Na₂SO₄, and the solvent is evaporated. The crude mixture is passed through a short silica column, eluting with petroleum ether / ethyl acetate 8:2 to provide the impure selenized intermediate. This intermediate is solubilized in dichloromethane, and a 30% H₂O₂ solution is added in excess (>2 equivalents) at 0°C. After 1 hour at room temperature, the reaction is stopped by adding a saturated aqueous solution of Na₂S₂O₃. The mixture is extracted with diethyl ether and the organic phases are dried with Na2SO4.Purification by silica chromatography (petroleum ether / dichloromethane eluent 4:1) leads to pure compound D. Example 3 Synthesis of compound H

[0088]

[0089] Compound D is diluted in a 1:1 THF / water mixture, and LiOH (2 equivalents) is added at room temperature. After stirring at 50°C for 12 h, the reaction is stopped by adding a 1N aqueous HCl solution and extracted with ethyl acetate. The organic phases are evaporated, and the residue is chromatographed on silica gel (petroleum ether / ethyl acetate / dichloromethane eluent 5:3:2) to yield compound H as colorless crystals. Example 4 Synthesis of compound C

[0090]

[0091] Compound C, a methyl regioisomer of compound H, was obtained as a by-product of the alkaline hydrolysis of a regioisomeric mixture of compound D, after purification. Example 5 Synthesis of compound E Step 1 Preparation of the bicyclic dihydrooxepin intermediate

[0092]

[0093] One equivalent of Cs₂CO₃ is added to a solution of 1,3-cyclohexadione (one equivalent) in DMSO (0.1 mol / L), and the solution is stirred at 20°C for 20 min. Next, a solution of 1,4-dibromo-2-butene (one equivalent) in DMSO is added to the mixture at 20°C. The reaction mixture is stirred at 20°C for 12 h before being diluted with Et₂O and stopped with cold water (0°C). The organic phase is washed three times with brine (saturated NaCl solution). The aqueous phases are then extracted three times with diethyl ether. The combined organic extracts are dried over Na₂SO₄ and concentrated under reduced pressure, avoiding heating above 20°C. The residue is then purified by flash chromatography on a silica gel using a chilled column (<10°C) to provide the intermediate bicyclic dihydrooxepin. Step 2 Preparation of compound E (2,5-dihydrobenzoxepine)

[0094]

[0095] The preceding compound is dihydroxylated in the presence of OsO₄ (5 mol%) and N-methylmorpholine-N-oxide (1.3 equivalents) in a 3:1 acetone / water mixture at 0°C for 20 min. After concentration, the reaction mixture is purified by silica chromatography (eluent: ethyl acetate) to yield the corresponding diol (white crystals). This is then converted to the dimesylate by the action of methanesulfonyl chloride (5 equivalents) in pyridine. After 16 h at room temperature, the dimesylated product is extracted with ethyl acetate, and the organic phases are washed with aqueous 1N HCl, then with saturated NaHCO₃, and finally with brine. After drying over MgSO₄ and concentration, the dimesylate is obtained without further purification. The crude product is diluted in DMSO, then a tetrabutylammonium fluoride solution in THF (1M, 4 equivalents) is added at 0°C and the mixture is stirred for 1 hour at room temperature (20°C).After extraction with ethyl acetate and purification by silica chromatography (eluent: petroleum ether / ethyl acetate 9:1), compound E is obtained in the form of white crystals. Example 6 Testing the herbicidal activity of compounds according to the invention and of a comparator compound

[0096] The compounds were tested on Arabidopsis thaliana seedlings grown hydroponically at the cotyledon stage. Sterile seeds were germinated under light in a culture plate, in the presence of 200 µL of nutrient medium.

[0097] After five days of culture (time 0 of the test), the nutrient medium is replaced by an equivalent volume (200 µL) of the same medium containing the compound to be tested at different concentrations.

[0098] The results are summarized in Table 2 below.

[0099] The manifestation of herbicidal activity is indicated by A for Active in the case where the plant is killed, that is to say when both cotyledons have lost all of their green colour, 24 h and 96 h after application of the product.

[0100] The absence of herbicidal activity is indicated by "N" for Not active, in cases where no biological activity is observed. Name Formula developed Activity after 12:00 AM Activity after 96 hours 100 µg / mL 50 µg / mL 10 µg / mL 100 µg / mL 50 µg / mL 10 µg / mL Compound A A A N A A N Compound H A A A A A A Compound C A A A A A A Compound D N N N A A N Compound E (comparative) N N N N N N

[0101] Thus, all the compounds have a herbicidal effect, whereas a simplified analogue without phenalkyl Ph(CH2)n shows only a very weak herbicidal effect on seedlings after 120 h at a high concentration of 100 µg / mL.

Claims

1. Use as herbicide, in particular as root-penetrating, systemic and / or post-emergence herbicide, of at least one compound chosen from the compounds of general formula (I) said compound of general formula (I) corresponding to the general formula (Ia): in which • n is an integer ranging from 1 to 6, • R1, R2 and R3 independently of one another represent a hydrogen or halogen atom, a C1 to C5 alkyl radical or a group chosen from -OH, -COOH, -COOR", -OR" and -SO2R'', with R" being a C1 to C5 alkyl radical, with it being possible for the alkyl radicals to be substituted by one or more halogen atoms or hydroxyl groups, with R2 preferably representing a -COOH group, • R represents a C1 to C5 alkyl or cycloalkyl radical, optionally substituted by one or more halogen atoms, and • the symbol indicates a single bond or a double bond in position 2, 3 or 4 of the 7-membered fused heterocycle, with at least one double bond being present, and organic or inorganic salts thereof and isomers thereof.

2. Use according to Claim 1, characterized in that R is an alkyl radical having 1 to 3 carbon atoms, and preferably is a methyl, the alkyl radical optionally being substituted by one or more halogen atoms.

3. Use according to Claim 1 or 2, characterized in that n is an integer ranging from 1 to 3 and preferably is equal to 2.

4. Use according to any one of the preceding claims, characterized in that said compound corresponds to the general formula (Ib): with R, R1, R2 and n being as defined in any one of the preceding claims, and organic or inorganic salts thereof and isomers thereof, with R2 preferably representing a - COOH group.

5. Use according to any one of the preceding claims, characterized in that the fused heterocycle has a single double bond in position 2, 3 or 4, preferably in position 3.

6. Use according to any one of the preceding claims, characterized in that R1 is chosen from a hydrogen atom and a -COOH group, and preferably is a hydrogen atom.

7. Use according to any one of the preceding claims, characterized in that R2 is chosen from a hydrogen atom, a -COOH group and a -COOR" group, with R" being a C1 to C5 alkyl radical, in particular with R" being a methyl; preferably R2 is chosen from a hydrogen atom and a -COOH group; and more preferentially R2 is a -COOH group.

8. Use according to any one of the preceding claims, characterized in that said compound corresponds to the general formula (Ic): position 3 or 4 being substituted by a radical R, with R, R1 and n being as defined in any one of the preceding claims, or one of the organic or inorganic salts and isomers thereof.

9. Use according to any one of the preceding claims, characterized in that said compound is chosen from: and and organic or inorganic salts thereof and isomers thereof, and preferably chosen from: and and organic or inorganic salts thereof and isomers thereof.

10. Use according to any one of the preceding claims, characterized in that said compound is used in an isolated, natural or synthetic form; or said compound is used in the form of a plant extract containing said compound, in particular in the form of an extract of hepatic plants containing said compound; and / or said compound is used in a diluted form, in particular in an aqueous medium.

11. Use according to any one of the preceding claims, characterized in that said compound is generated in situ or just before use, in particular by hydrolysis, from a precursor.

12. Phytotoxic composition comprising at least one compound as defined in any one of Claims 1 to 11 in combination with at least one additive chosen from fertilizers, growth regulators and auxiliary herbicides, especially being in the form of a solid composition, in particular in the form of a powder or of granules, or a liquid composition, in particular in concentrated or ready-to-use form, in particular in solution or in emulsion, the auxiliary herbicides being chosen from ammonium nonanoate, nonanoic acid, fatty acids of intermediate chain length and salts thereof, urea derivatives, borax, copper sulfate, carboxylic acids and salts thereof, nitrogen-based compounds, calcium salts, and mixtures thereof.

13. Method for controlling the development of and / or treating undesirable plants on the surface of a target zone, comprising contacting the target zone with an effective amount of at least one compound as defined in any one of Claims 1 to 11 or at least one composition according to Claim 12, the contacting in particular taking place by spraying at least one compound as defined in any one of Claims 1 to 11 or at least one composition according to Claim 12.