WO1996006089A1

WO1996006089A1 - Substituted biphenyl derivatives and their use as herbicides

Info

Publication number: WO1996006089A1
Application number: PCT/EP1995/003285
Authority: WO
Inventors: Arnim Köhn; Heinrich Franke; Wilfried Franke; Jürgen Bohner; Richard Rees
Original assignee: Hoechst Schering Agrevo Gmbh
Priority date: 1994-08-22
Filing date: 1995-08-18
Publication date: 1996-02-29
Also published as: TW281623B; TR199501046A1; IL114950A0; AU3346895A

Abstract

The invention relates to biphenyl compounds having general formula (I) in which X is oxygen, sulphur, ⊃NH, ⊃NCH3, ⊃NCHO, ⊃NCOCH3, ⊃NSO2CH3 or ⊃NCOCF3; Y is oxygen, sulphur, ⊃NH, ⊃NCH3, ⊃NC2H5, ⊃NCHO, ⊃NSO2CH3, ⊃NCH2CN, ⊃NCOCH3, ⊃NCOCF3 or ⊃NCH2Ph; R1 is hydrogen, C¿1?-C4 alkyl, C1-C2 alcoxy, phenyl-C1-C2 alkoxy, hydroxy-C1-C2 alkyl, C1-C2-alkoxy-C1-C2 alkyl, halo-C1-C2 alkyl, halo-C1-C4 alkoxy, C1-C2 alkylthio, C2-C3 alkenyl, hydroxycarbonyl, C1-C2 alkyloxycarbonyl, C1-C2 alkylaminocarbonyl, C1-C2 dialkylaminocarbonyl, aminocarbonyl, halogen, nitro, cyano, C1-C3 alkylamino, C1-C3 dialkylamino, acetylamino, -COR?7, NR8R9¿ or a heterocyclic 3-6-membered ring which can be interrupted once or more by O, S, or N; R7 is hydrogen, C¿1?-C3 alkyl, or halo-C1-C3 alkyl; R?8R9¿ are the same or different and are hydrogen, C¿1?-C3 alkyl or COR?10; R10¿ is hydrogen, C¿1?-C3 alkyl, halo-C1-C3 alkyl or phenyl, R?2 is C¿1-C4 alkyl, C1-C3 alkoxy, C1-C3 haloalkyl, C1-C3 haloalkoxy, halogen, C1-C3 haloalkylthio, C1-C3 alkylthio, cyano or nitro; n = 1, 2 and 3. The invention also includes herbicidal formulations of the compounds and their use as herbicides.

Description

SUBSTITUTED BIPHENYL DERIVATIVES AND THEIR USE AS HERBICIDES

The invention relates to new substituted biphenyls, to their production and to intermediate products for their production and to their use as herbicides.

It is already known that acetamidobiphenyl compounds have herbicidal properties (WO 93/11097). Frequently, however, the herbicidal action of the known compounds is insufficient, or there is a suitable herbicidal action but selectivity problems arise in principal agricultural crops.

It is the object of the present invention to provide new biphenyls which do not have these disadvantages and which are superior to the compounds known to date as regards their biological properties.

It was found that substituted biphenyls of general formula I

in which X is oxygen, sulphur, >NH, >NCH₃, >NCHO, >NCOCH₃, >NSO₂CH₃ or >NCOCF₃

Y is oxygen, sulphur, >NH, >NCH₃, >NC₂H₅, >NCHO, >NSO₂CH₃,

>NCH₂CN, >NCOCH₃, >NCOCF₃ or >NCH₂Ph,

R¹ is hydrogen, C₁-C₄ alkyl, C₁-C₂ alkoxy, phenyl-C₁-C₂ alkoxy, hydroxy-C₁-C₂ alkyl, C₁-C₂-alkoxy-C₁-C₂ alkyl, halo-C₁-C₂ alkyl, halo-C₁-C₄ alkoxy, C₁-C₂ alkylthio,

C₂-C₃ alkenyl, hydroxycarbonyl, C₁-C₂ alkyloxycarbonyl,

C₁-C₂ alkylaminocarbonyl, C₁-C₂ dialkylaminocarbonyl, aminocarbonyl, halogen, nitro, cyano, C₁-C₃ alkylamino,

C₁-C₃ dialkylamino, acetylamino, -COR⁷, NR⁸R⁹ or a heterocyclic 3-6-membered ring which can be interrupted once or more by O, S or N,

R⁷ is hydrogen, C₁-C₃ alkyl or halo-C₁-C₃ alkyl,

R⁸R⁹ are the same or different and are hydrogen, C₁-C₃ alkyl or

COR¹⁰,

R¹⁰ is hydrogen, C₁-C₃ alkyl, halo-C₁-C₃ alkyl or phenyl,

R² is C₁-C₄ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃ haloalkoxy, halogen, C₁-C₃ haloalkylthio, C₁-C₃ alkylthio, cyano or nitro,

R³, R⁴, R⁵ and R⁶ are independently of one another hydrogen, halogen, nitro, cyano, C₁-C₄ alkyl, C₁-C₃ alkoxy, C₁-C₃ thioalkoxy, C₁-C₃ haloalkyl, C₁-C₃ haloalkoxy, carboxy, C₁-C₄ alkyloxycarbonyl, C₁-C₄ alkylaminocarbonyl,C₁-C₄ dialkylaminocarbonyl, aminocarbonyl, amino, C₁-C₄ alkylamino, C₁-C₄ dialkylamino, acetylamino or trifluoracetylamino and n = 1, 2 and 3, with the proviso that if R¹ , R², R³, R⁴, R⁵ and R⁶ is hydrogen and X is oxygen, Y cannot be oxygen or sulphur and if R¹, R², R³, R⁴, R⁵ and R⁶ is hydrogen and X signifies -NH-, Y cannot be sulphur, have a superior herbicidal action compared with the known compounds.

The designation halogen encompasses fluorine, chlorine, bromine and iodine. The designation alkyl includes cases where the carbon chain can be branched or unbranched.

Those compounds of formula I in which R¹ = 5 C₁-C₄ alkyl, 5 C₁-C₂ alkoxy, cyano or halogen, n=1 and R² = C₁-C₃ haloalkyl, C₁-C₃ haloalkoxy or halogen are preferred.

The compounds of general formula I according to the invention can be produced

a) by reacting a compound of general formula II

in which R , R , n and X have the meaning given in general formula I, optionally in the presence of a base and of a solvent, with a benzo-condensed heterocycle of general formula III

in which Y , R³ , R⁴ , R⁵ and R⁶ have the meaning given in general formula I and Z stands for a leaving group such as e . g . Cl , Br , I , -SO₂ alkyl or -SO₂-aryl , or b ) by reacting a compound of general formula IV

in which R¹, R² and n have the meaning given in general formula I, optionally in a solvent and in the presence of mercury (II) oxide with a compound of general formula V

in which X, R³, R⁴, R⁵ and R⁶ have the meaning given in general formula I, or c) by reacting a compound of general formula VI

in which R¹ , n, X, Y, R , R⁴, R⁵ and R⁶ have the meaning given in general formula I and U stands for bromine, iodine or -O-SO₂-CF₃, with a compound of general formula VII

in which R² has the meaning given in general formula I and V stands for Li, MgCl, MgBr, B(OH)₂ or trialkyl tin, in the presence of a catalyst.

The subject-matter of the invention are also compounds of general formulae Ila and lIb

where, in the case of compounds of general formula Ila, in which

R² = OCH₃, NO₂ or CN, R¹ cannot be hydrogen or 5-CH₃, or when R²= CF₃, R¹ cannot be 5-NHAc or 5-NO_O, or when R² = Cl, R¹ cannot be 3-Cl, 5NHAC or 5-NO₂, or when R² = CH₃, R¹ cannot be 3-CH₃ or 5- CH₃ or when R² = F, R¹ cannot be hydrogen, 5-NO₂ or 5-NHAc and in the case of compounds of general formula lIb, in which R² = CH₃, R¹ cannot be 5-CH₃, which serve as intermediate products for the production of compounds of formula I.

The intermediate products of general formula Ila can be produced for example i ) by reacting a compound of general formula VIII

in which R¹ and n have the meaning given in formula I and U stands for bromine, iodine or -O-SO₂CF₃, with a compound of general formula IX

in which R² has the meaning given in formula I and V stands for Li, MgCl, MgBr, B(OH)₂ or trialkyl tin, in the presence of a catalyst.

The intermediate products of general formula lIb can be produced for example ii) by reacting an aniline of general formula X

in which R¹, R² and n have the meaning given in general formula I, according to methods customary in the literature.

In process variant A), acetonitrile, dimethyl formamide and dimethyl sulphoxide are suitable in particular as solvents. Tertiary amines, such as e.g. pyridines, alkali or alkaline earth carbonates or hydrogen carbonates, alkaline earth oxides or sodium or potassium hydride can be used as bases.

Process variants B) and C) are carried out analogously to the processes described in the literature:

Process variant b): J. Garin et al.; J. Heterocyclic Chem. 28,

359 (1991) and

Process variant C): Hirohiko Sugimoto et al.; J. Org. Chem. 1988,

53, 2263-2267; A. Hetzheim et al.; Pharmazie 42, 80-81 (1987).

The compounds according to the invention are processed in the usual manner. Purification takes place e.g. by crystallization or column chromatography.

As a rule, the compounds according the invention are colourless or slightly yellow-coloured crystalline or viscous substances, some of which are readily soluble in chlorinated hydrocarbons, such as for example methylene chloride or chloroform, ethers, such as for example diethyl ether or tetrahydrofuran, alcohols, such as for example methanol or ethanol, ketones, such as for example acetone or butanone, amides, such as for example dimethyl formamide, or also sulphoxides, such as for example dimethyl sulphoxide.

The active ingredients according to the invention show a good herbicidal action in the case of broad-leaved weeds and grasses. Selective use of the active ingredients according to the invention is possible in various crops, e.g. in rapeseed, beet, soyabeans, cotton, rice, maize, barley, wheat and other types of cereal. According to the invention, individual analogous active ingredients are also particularly suitable as selective herbicides in beet, cotton, soya, maize and cereals. The compounds can also be used for weed control in perennial crops, such as e.g in forest, ornamental tree and shrub, fruit, wine, citrus, nut, banana, coffee, tea, rubber, palm oil, cocoa, berried fruit and hop plantations.

The active ingredients according to the invention can be used e.g. with the following genera of plants:

Dicotyledonous weeds of the genera Sinapis, Lepidium, Galium, Stellaria, Matricaria, Anthemis, Galinsoga, Chenopodium, Brassica, Urtico, Senecio, Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum, Sesbania, Ambrosia, Cirsium, Sonchus, Solanum, Lamium, Veronica, Abutilon, Datura, Viola, Galeopsis, Papaver, Centaurea and Chrysanthemum and monocotyledonous weeds of the genera Avena, Alopecurus, Echinochloa, Setaria, Panicum, Digitaria, Poa, Eleusine, Brachiaria, Lolium, Bromus, Cyperus, Elymus, Sagittaria, Monocharia, Fimbristylis, Eleocharis, Ischaemum and Apera.

The application quantities fluctuate, depending on the type of application pre- and post-emergence, between 0.001 to 5 kg/ha.

The active ingredients according to the invention can also be used as a defoliant, a desiccant and as a haulm destroyer. Suitable as preparation forms are e.g. emulsion concentrates, suspensions and salts. The addition of higher proportions of wetting agent is advantageous in appropriate cases.

The action intensity and the speed of action can for example be promoted by action-enhancing additives, such as organic solvents, wetting agents and oils. Such additives thus permit a lowering of the active ingredient dosage in appropriate cases.

The active ingredients according to the invention or their mixtures are used expediently in the form of preparations, such as powders, scattering preparations, granulates, solutions, emulsions or suspensions, with the addition of liquid and/or solid carrier substances and diluents and optionally adhesives, wetting agents, emulsification and/or dispersion auxiliaries.

Suitable liquid carrier substances are for example aliphatic and aromatic hydrocarbons, such as benzene, toluene, xylene, cyclohexanone, isophorone, dimethyl sulphoxide, dimethyl formamide, also mineral oil fractions and vegetable oils.

Suitable as solid carrier substances are minerals, such as for example bentonite, silica gel, talc, kaolin, attapulgite, limestone and vegetable products, such as for example powders.

Surface-active substances that may be cited are for example calcium lignin sulphonate, polyethylene alkylphenyl ether, naphthalene sulphonic acids and their salts, phenol sulphonic acids and their salts, formaldehyde condensates, fatty alcohol sulphates and substituted benzene sulphonic acids and their salts.

The proportion of the active ingredient(s) in the various preparations can vary within wide limits. For example, the agents contain about 10 to 90 percent by weight active ingredient, about 90 to 10 percent by weight liquid or solid carrier substances and optionally up to 20 percent by weight surface-active substances. The agents can be applied in the usual manner, for example with water as carrier in spray-mix quantities of about 100 to 1000 litres/ha. Using the agents in so-called low-volume and ultra-low processes is also possible, as is their application in the form of so-called microgranulates.

These preparations can be produced in ways known per se, for example by grinding or mixing processes. If desired, preparations of the individual components can also be mixed just prior to their use, as is carried out in practice for example in the so- called tank-mix process.

Production of the starting material:

Process variant i

4-methyl-2-(3-trifluoromethyl)-phenol

A solution of 23.13 g (123 mmol) 2-bromo-4-methylphenol in 50 ml dimethoxyethane is mixed with 500 mg (0.71 mmol) bis- triphenylphosphine palladium dichloride and the mixture is stirred for 15 min at room temperature. 29.4 g (155 mmol) 3- trifluoromethylphenyl boric acid and a solution of 36.2 g (431 mmol) sodium hydrogen carbonate in 437 ml water are then added. The suspension is boiled under reflux for 16 hours. 231 ml of 1 molar sodium hydroxide solution are then added. The reaction mixture is extracted three times with 400 ml diethylether in each case. The combined organic phases are washed with 400 ml water, dried over magnesium sulphate, filtered and concentrated on a rotary evaporator. The residue is purified by means of column chromatography (silica gel; hexane/acetic ester = 4/1).

Yield: 12.6 g (50 mmol; 40 % of the theory) as colourless oil Rf (acetic acid) = 0.92

n_D ²⁰ = 1.5439

Process variant ii

4-methyl-2-(3-trifluoromethyl phenyl)-thiophenol

A solution of 2.41 g (4.51 mmol) bis-[4-methyl-2-(3- trifluoromethyl phenyl)-phenyl] disulphide in 20 ml tetrahydrofuran is mixed with 0.43 g (11.28 mmol) sodium borohydride and boiled under reflux. 20 ml methanol are added dropwise within an hour. 9.02 ml of 1 molar hydrochloric acid and 13.53 ml of 6 molar hydrochloric acid are then added dropwise at room temperature. The reaction mixture is then poured onto 60 ml iced water and extracted 4 times with 40 ml dichloromethane in each case. The combined organic phases are dried over magnesium sulphate, filtered and concentrated on a rotary evaporator.

Yield: 2.2 g (≈ 91 % of the theory) as yellow oil

n_D ^21.1 = 1.5624

Bis-[4-methyl-2(3-trifluoromethylphenyl )-phenyl] disulphide

10 g (39.8 mmol) 4-methyl-2-(3-trifluromethylphenyl) aniline are mixed with 20 ml iced water and 20 ml of 37 % hydrochloric acid and the mixture is stirred at 70°C for 20 minutes. A solution of 2.92 g (42.28 mmol) sodium nitrite in 7 ml water is then slowly added dropwise to the reaction mixture at 0°C. The reaction mixture is stirred for 15 minutes. A solution of 7.43 g (46.35 mmol) potassium ethyl xanthate in 10 ml water is then slowly added dropwise at 60°C and the mixture is stirred for a further 30 minutes at 60°C. The reaction mixture is poured onto 50 ml iced water and extracted three times with 200 ml diethylether in each case. The combined organic phases are washed once with 200 ml of 1 % sodium hydroxide solution and twice with 200 ml water in each case, dried over magnesium sulphate, filtered and concentrated on a rotary evaporator. The residue is dissolved in 30 ml diethyl ether and mixed under reflux with 9.29 g (166 mol) potassium hydroxide. The mixture is then boiled under reflux for 18 hours. The reaction mixture is then acidified with 1 molar sulphuric acid and extracted four times with 50 ml diethyl ether in each case. The combined organic phases are washed twice with 100 ml water in each case, dried over magnesium sulphate, filtered and concentrated. The residue is purified by means of column chromatography (silica gel; hexane/acetic ester = 9/1).

Yield: 2.5 g (≈ 24 % of the theory) as yellowish oil

R_f (hexane/acetic ester) = 0.56 The compounds of formula II are produced analogously:

The following examples describe the production of the compounds according to the invention.

Example 1 (Process variant A)

2-(4-methyl-3'trifluoromethyl-1,1'-biphenyl)-2-yloxybenzothiazole

A solution of 1.5 g (5.95 mmol) 4-methyl-2-(3- trifluoromethylphenyl)-phenol and 1.01 g (5.95 mmol) 2- chlorobenzothiazole in 5 ml dimethyl sulphoxide is mixed with 1.65 g (11.9 mmol) potassium carbonate and the mixture is stirred for 8 hours at 50°C. The reaction mixture is poured onto 50 ml iced water and extracted three times with 30 ml dichloromethane in each case. The combined organic phases are washed twice with 30 ml water, dried over magnesium sulphate and concentrated on a rotary evaporator. The residue is purified by means of column chromatography (silica gel; hexane/acetic ester = 4/1).

Yield: 2.14 g (5.55 mol ≈ 93 % of the theory) as slightly yellowish oil

n_D ²⁰-⁸ = 1.6047

R_f (acetic ester) = 0.76

Example 2 (Process variant B)

N-(4-methyl-3'-trifluoromethyl-1,1 '-biphenyl)-2-yl- benzothiazolamine

A solution of 0.85 g (6.82 mmol) 2-aminothiophenol in 15 ml toluene is added dropwise to a solution of 2.0 g (6.82 mmol) 4- methyl-2-(3-trifluromethylphenyl)-phenylisothiocyanate in 20 ml toluene. The mixture is then boiled under reflux for 2 hours. After adding 1.48 g (6.82 mmol) mercury(II) oxide, the mixture is boiled under reflux for 4 hours. The reaction mixture is filtered over silica gel and concentrated on a rotary evaporator. The residue is purified by means of column chromatography (silica gel; hexane/acetic ester = 4/1).

Yield: 1.8 g (4.68 mmol ≈ 69 % of the theory) as colourless crystals.

F_p. = 163 - 164°C

R_f = 0.67

Example 3 (Process variant C)

2-(3'-trifluoromethyl-1,1'-biphenyl)-2-yloxy-benzoxazole

A solution of 2.5 g (8.6 mmol) 2-(2-bromophenoxy) benzoxazole in 15 ml dimethoxyethane is mixed with 0.2 g bis- ( triphenylphosphine) palladium(II) chloride and the mixture is stirred for 15 min at room temperature. 1.8 g (9.5 mmol) 3- trifluoromethyl boric acid and a solution of 2.2 g (25.8 mmol) sodium hydrogen carbonate in 25 ml water are then added. The suspension is boiled under reflux for 10 hours. 25 ml of 1 molar sodium hydroxide solution are then added. The reaction mixture is extracted three times with 40 ml diethyl ether in each case. The combined organic phases are washed with 40 ml water, dried over magnesium sulphate, filtered and concentrated on a rotary evaporator. The residue is purified by means of column chromatography (silica gel; hexane/ether = 2:1).

Yield: 1.8 g (« 59 % of the theory) as colourless oil

R_f (acetic ester) = 0.75

n_D ²⁰ = 1.5769

2-(2-bromophenoxy)-benzoxazole

A solution of 3.5 g (20 mmol) 2-bromophenol and 3.1 g (20 mmol) 2-chlorobenzoxazole in 30 ml dimethyl sulphoxide is mixed with 4 g (28.85 mmol) potassium carbonate and the mixture is stirred for 8 hours at 50°C. The reaction mixture is poured onto 150 ml iced water and extracted three times with 100 ml dichloromethane in each case. The combined organic phases are washed twice with 70 ml water, dried over magnesium sulphate and concentrated on a rotary evaporator. The residue is purified by means of column chromatography (silica gel; hexane/acetic ester = 4/1).

Yield: 4.0 g (≈ 69 % of the theory)

R_f(acetic ester) = 0.78

Melting point = 57 - 59°C The following compounds of general formula I are produced in analogous manner:

The following examples explain the use of the compounds according to the invention. In the application examples:

AS = active substance

TRZAX Triticum aestivum 0 = no damage

ZEAMX Zea mays 1 = 1 - 25 % damage

ABUTH Abutilon theophrasti 2 = 24 - 74 % damage

GALAP Galium aparine 3 = 75 - 89 % damage

IPOSS Ipomoea purpurea 4 = 90 - 100 % damage

MATCH Matricaria chamomilla

POLSS Polygonum sp.

SEBEX Sesbania exaltata

SOLSS Solanum sp.

VERPE Veronica persica

VIOSS Viola sp.

ORYSA Oryza sativa

ECHCG Echinochloa crus-galli

CYPDI Cyperus difformis

MOOVA Monochoria vaginalis Application example A

The plant species listed were treated in a green house after emergence with the compounds listed in the given application quantity of active ingredient/ha. For this purpose the compounds were sprayed uniformly over the plants as an emulsion with 500 litres water/ha. Three weeks after the treatment the compounds according to the invention displayed a high cultivated plant selectivity in wheat and maize with excellent action against weeds.

Application example B

The compounds listed in the table were applied by pipetting onto a water surface area of approx. 170 cm² in a green house, the test plants being used in the pre-emergence phase and in the 1-2 leaf phase.

After 2 weeks it was shown that the compounds according to the invention have a strong action against important rice weeds and are at the same time selective as regards water rice.

Claims

Patent claims 1. Substituted biphenyls of general formula I

in which

X is oxygen, sulphur, >NH, >NCH₃, >NCHO, >NCOCH₃,

>NSO₂CH₃ or >NCOCF₃

Y is oxygen, sulphur, >NH, >NCH₃, >NC₂H₅, >NCHO,

>NSO₂CH₃, >NCH₂CN, >NCOCH₃, >NCoCF₃ or >NCH₂Ph, R¹ is hydrogen, C₁-C₄ alkyl, C₁-C₂ alkoxy, phenyl-C₁-C₂ alkoxy, hydroxy-C₁-C₂ alkyl, C₁-C₂-alkoxy-C₁-C₂ alkyl, halo-C₁-C₂ alkyl, halo-C₁-C₄ alkoxy, C₁-C₂ alkylthio, C₂-C₃ alkenyl, hydroxycarbonyl, C₁-C₂ alkyloxycarbonyl, C₁-C₂ alkylaminocarbonyl, C₁-C₂ dialkylaminocarbonyl, aminocarbonyl, halogen, nitro, cyano, C₁-C₃ alkylamino, C₁-C₃ dialkylamino, acetylamino, -COR⁷, NR⁸R⁹ or a heterocyclic 3-6-membered ring which can be interrupted once or more by O, S or N,

R⁷ is hydrogen, C₁-C₃ alkyl or halo-C₁-C₃ alkyl, R⁸ R⁹ are the same or different and are hydrogen, C₁-C₃ alkyl or COR ¹⁰

R¹⁰ is hydrogen, C₁-C₃ alkyl, halo-C₁-C₃ alkyl or phenyl,

R² is C₁-C₄ alkyl, C₁-C₃ alkoxy, C₁-C₃ haloalkyl, C₁-C₃ haloalkoxy, halogen, C₁-C₃ haloalkylthio, C₁-C₃ alkylthio, cyano or nitro, and R⁶ are independently of one another hydrogen, halogen, nitro, cyano, C₁-C₄ alkyl, C₁-C₃ alkoxy, C₁-C₃ thioalkoxy, C₁-C₃ haloalkyl, C₁-C₃ haloalkoxy , carboxy , C₁ -C₄ alkyloxycarbonyl , C₁ -C₄ alkylaminocarbonyl, C₁-C₄ dialkylaminocarbonyl, aminocarbonyl, amino, C₁-C₄ alkylamino, C₁-C₄ dialkylamino, acetylamino or trifluoracetylamino and n 1 , 2 and 3. with the proviso that if R¹, R², R³, R⁴, R⁵ and R⁶ is hydrogen and X is oxygen, Y cannot be oxygen or sulphur and if R¹ , R², R³, R⁴, R⁵ and R⁶ is hydrogen and X signifies -NH-, Y cannot be sulphur.

2. Compounds of formula I in which R¹ = 5 C₁-C₄ alkyl, 5 C₁-C₂ alkoxy, cyano or halogen, n=1 and R² = C₁-C₃ haloalkyl, C₁- C₃ haloalkoxy or halogen.

3. Compounds of general formulae Ila and lIb

where R¹, R² and n have the meaning given in formula I, but in the case of compounds of general formula Ila in which R² = OCH₃, NO₂ or CN, R¹ cannot be hydrogen or 5-CH₃, or when R²= CF₃, R¹ cannot be 5-NHAc or 5-NO₂,

or when R²=Cl, R¹ cannot be 3-Cl, 5NHAc or 5-NO₂,

or when R²=CH₃, R¹ cannot be 3-CH₃ or 5-CH₃

or when R²=F, R¹ cannot be hydrogen, 5-NO₂ or 5-NHAc and in the case of compounds of general formula lIb, in which

R² = CH₃, R¹ cannot be 5-CH₃, as intermediate products for the production of compounds of formula I.

4. Agent with herbicidal action characterized by a content of at least one compound according to claims 1 and 2.

5. Agent with herbicidal action according to Claim 4 mixed with carrier substances and/or auxiliaries.

6. Use of compounds according to Claims 1 and 2 for controlling monocotyledonous and dicotyledonous types of weeds.