Heterocyclic oxy-phenoxyacetic acid derivatives and their use as herbicides

Abstract: A heterocyclic oxy-phenoxyacetic acid derivative of the formula: wherein R is a pyridyl or quinoxalinyl group optionally bearing thereon not more than two substituents chosen from halogen and halo(lower)alkyl; R¹ and R² are each hydrogen or lower alkyl; and R³ is -NR⁴R⁵, -NHR⁶ or -OR⁷ (in which R⁴ and R⁵ are each hydrogen or lower alkyl or, when taken together with the adjacent nitrogen atom, represent a saturated nitrogen-containing 5- or 6-membered heterocyclic group optionally having one additional ring hetero atom chosen from nitrogen, oxygen and sulfur, which may bear thereon not more than two lower alkyl groups; R⁶ is lower cycloalkyl, substituted or unsubstituted aryl, or a saturated or unsaturated 5- or 6-membered heterocyclic group having at least one ring hetero atom chosen from nitrogen, oxygen and sulfur or a group of the formula: -NR⁸R⁹ (in which R⁸ and R⁹ are each hydrogen or lower alkyl or, when taken together, represent a lower alkylidene group); and R⁷ is hydrogen, lower alkyl, lower alkoxy, substituted or unsubstituted aryl(lower)alkyl, substituted or unsubstituted aryloxy­ (lower)alkyl, halo(lower)alkyl, hydroxy(lower) alkyl or lower alkoxy(lower)alkyl), or its salt, which is useful as a herbicide, and including processes for its production.

Description: The present invention relates to heterocyclic oxy-phenoxyacetic acid derivatives and their use as herbicides. There are known various heterocyclic oxy-phenoxyacetic acid derivatives, which are commercially available as herbicides. Their typical examples are as follows: These heterocyclic oxy-phenoxyacetic acid derivatives are characteristic in producing a strong herbicidal effect against a variety of weeds with weak phytotoxicity on broad-leaved crop plants. However, their intergeneric selectivity on monocotyledonous plants is relatively small so that they sometimes cause phytotoxicity on crop plants such as wheat, barley and rice plants while they do not produce any herbicidal effect on certain perennial weeds. Accordingly, their practical use is restricted as to application field, application mode, etc. As the result of an extensive study, it has now been found that certain heterocyclic oxy-phenoxyacetic acid derivatives having a fundamental chemical structure corresponding to the condensation product between the carboxyl group of a heterocyclic oxy-phenoxyacetic acid and the amino group of an aminoxyacetic acid produces a remarkable herbicidal activity against a variety of weeds without exerting any material phytotoxicity on broad-leaved crop plants. It is notable that they show a significant intergeneric selectivity on monocotyledonous plants. The present invention is based on the above finding. The objective compound of the present invention is a heterocyclic oxy-phenoxyacetic acid derivative of the formula: wherein R is a pyridyl or quinoxalinyl group optionally bearing thereon not more than two substituents chosen from halogen and halo(lower)alkyl; R¹ and R² are each hydrogen or lower alkyl; and R³ is -NR⁴R⁵, -NHR⁶ or -OR⁷ (in which R⁴ and R⁵ are each hydrogen or lower alkyl or, when taken together with the adjacent nitrogen atom, represent a saturated nitrogen-containing 5- or 6-membered heterocyclic group optionally having one additional ring hetero atom chosen from nitrogen, oxygen and sulfur, which may bear thereon not more than two lower alkyl groups; R⁶ is lower cycloalkyl, substituted or unsubstituted aryl, or a saturated or unsaturated 5- or 6-membered heterocyclic group having at least one ring hetero atom chosen from nitrogen, oxygen and sulfur or a group of the formula: -NR⁸R⁹ (in which R⁸ and R⁹ are each hydrogen or lower alkyl or, when taken together, represent a lower alkylidene group); and R⁷ is hydrogen, lower alkyl, lower alkoxy, substituted or unsubstituted aryl(lower)alkyl, substituted or unsubstituted aryloxy(lower)alkyl, halo(lower)alkyl, hydroxy(lower)alkyl or lower alkoxy(lower)alkyl), or its salts. In this specification, the term "lower" is intended to mean a group having not more than 8 carbon atoms, particularly not more than 6 carbon atoms. Examples of "lower alkyl" include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, etc. As "lower cycloalkyl", there may be exemplified cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. "Halogen" includes chlorine, bromine, fluorine and iodine, and preferred are chlorine and fluorine. "Halo(lower)alkyl" covers monochloromethyl, difluorochloromethyl, trifluoromethyl, etc., and preferred is trifluoromethyl. "Aryl" includes phenyl, naphthyl, etc. The substituent(s) which may be present on the aryl group are lower alkyl, lower alkoxy, halogen, etc. Examples of the "saturated nitrogen-containing 5- or 6-membered heterocyclic group" are pyrrolidino, piperidino, piperazino, morpholino, thiamorpholino, etc. The "saturated or unsaturated 5- or 6-membered heterocyclic group" may be the one having at least one ring hetero atom, usually one to three ring hetero atoms and preferably one or two ring hetero atoms chosen from nitrogen, oxygen and sulfur in addition to the ring carbon atoms, and its examples are imidazolyl, pyrolyl, pyrrolidyl (including pyrrolidino), pyridyl, piperidyl (including piperidino), pyrazinyl, pyrimidinyl, pyridazinyl, piperazinyl (including piperazino), furyl, morpholynyl (including morpholino), piranyl, thienyl, etc. "Lower alkylidene" includes methylene, ethylidene, vinylidene, propylidene, isopropylidene, butylidene, isobutylidene, pentylidene, hexylidene, etc. The heterocyclic oxy-phenoxyacetic acid derivative (I) of the present invention may be in a free form or a salt form. When in a salt form, it may be a salt as to the carboxyl group represented by -COR³ or an acid addition salt as to the basic nitrogen atom. Examples of the former salt are an alkali metal (e.g. sodium, potassium) salt, an alkaline earth metal (e.g. calcium, barium, magnesium) salt, an organic amine (e.g. ammonium, diethylamine, triethylamine, pyridine, picoline) salt, etc. Examples of the latter salt are an inorganic acid (e.g. hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid) salt, an organic acid (e.g. acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, malic acid, maleic acid, citric acid, benzoic acid, methane-sulfonic acid) salt, etc. The heterocyclic oxy-phenoxyacetic acid derivative (I) can include an asymmetric carbon atom and has its optical isomers. It may be used as a herbicide in a d-or 1-form, or in a mixture comprising those forms in an optional proportion. The heterocyclic oxy-phenoxyacetic acid derivative (I) can be produced by various procedures, among which a typical example comprises reacting a carboxylic acid of the formula: wherein R and R¹ are each as defined above, or its reactive derivative on the carboxy group, with an amine of the formula: wherein R² and R³ are each as defined above. As the reactive derivative of the carboxylic acid (II) on the carboxyl group, there may be exemplified acid halides (e.g. acid chloride), acid anhydrides, esters, active amides, etc. In case of acid anhydrides, there may be used mixed acid anhydrides with aliphatic acids (e.g. pivalic acid, trichloroacetic acid), dialkylphosphoric acids, dialkylphosphorous acids, alkylcarbonic acids or the like. Examples of the esters are methyl ester, ethyl ester, cyanomethyl ester, p-nitrophenyl ester, N-hydroxysuccinimide ester, etc. As the active amides, there are employed amides with imidazole, alkylimidazole, etc. When the carboxylic acid (II) itself is reacted with the amine (III), the reaction is normally effected in an inert solvent (e.g. dioxane, methylene chloride, chloroform, ether, tetrahydrofuran (THF), acetone, dimethylformamide (DMF), dimethylsulfoxide (DMSO), pyridine, acetonitrile, benzene, toluene, xylene) in the presence of a dehydrating agent (e.g. SOCl₂, SO₂Cl₂, POCl₃, PBr₃, PCl₅, polyphophoric acid (PPA)) or a condensating agent (e.g. N,N′ dicyclohexylcarbodiimide (DCC), N-cyclohexyl-N′-morpholinoethylcarbodimide, N,N′-diisopropylcarbodiimide, ClCO₂CH₃, ClCO₂C₂H₅, BrCO₂CH₃, (CH₃CO)₂O, Woodward reagent). etc. The use of an activating agent such as silicon tetrachloride or titanium chloride in an appropriate solvent such as dry pyridine is also favorable. The above reaction is ordinarily carried out at a temperature from room temperature to the refluxing temperature, particularly from about 0 to 100°C. When the acid halide or acid anhydride of the carboxylic acid (II) is reacted with the amine (III), the presence of excess of the amine (III) or a tertiary base such as pyridine in the reaction system is preferred for elimination of hydrogen halide or any other acid by-product. Also, there may be adopted the Schotten-Baumann method comprising addition of the acid halide to a mixture of the amine (III) and a base such as sodium hydroxide, sodium acetate, sodium carbonate or potassium carbonate kept at a relatively low temperature while stirring. When the ester of the carboxylic acid (II) is used, it may be reacted with the amine (III) at room temperature or while refluxing for ammonolysis, followed by removal of the by-product alcohol under distillation. Performance of such reaction in an inert solvent (e.g. benzene, dimethylformamide, dimethylsulfoxide, tetrahydrofuran-hexane) in the presence of a base (e.g. sodium methoxide, n-butyl lithium, sodium hydride) is favorable for increasing the yield. The above reaction is usually carried out at a temperature from room temperature to the refluxing temperature, particularly from about 0 to 100°C. Another typical procedure for production of the heterocyclic oxy-phenoxyacetic acid derivative (I) is as follows: wherein R¹⁰ is lower alkyl, X is halogen, and R, R¹, R², R⁴ and R⁵ are each as defined above. Namely, the carboxylic acid (II) or its reactive derivative at the carboxyl group is reacted with hydroxylamine (hydrochloride) in the presence of a base to give the N-hydroxyamide (IV), which is reacted with an alkyl haloalkanoate in the presence of an acid-eliminating agent to give the phenoxyacetic acid derivative (I′). This phenoxyacetic acid derivative (I′) is then hydrolyzed with an alkali, and the resultant phenoxyacetic acid derivative (I″) is reacted with an amine to give the phenoxyacetic acid derivative (I‴). Said phenoxyacetic acid derivative (I′) is also reacted with an alkylating agent to give the phenoxyacetic acid derivative (I″″). Practical embodiments for production of the heterocyclic oxy-phenoxyacetic acid derivative (I) are illustratively shown in the following Reference Examples and Examples. Reference Example 1 Production of methyl aminoxyacetate (H₂NOCH₂COOCH₃):- To a suspension of aminoxyacetic acid ( 1 / 2HCl) (5 g) in dry methanol (20 ml), thionyl chloride (12 ml) was dropwise added at -78°C, and the resultant mixture was gradually returned to room temperature and allowed to stand overnight, followed by removal of excess methanol and thionyl chloride by distillation to give methyl aminoxyacetate (hydrochloride) (5.0 g). Yield, 78 %. Reference Example 2 Production of N-ethylaminoxyacetamide (H₂NOCH₂CONHC₂H₅):- A solution of aminoxyacetic acid ( 1 / 2HCl) (3.5 g) and two droplets of dimethylformamide in thionyl chloride (8 ml) was stirred under reflux for 1 hour, followed by removal of excess thionyl chloride by distillation. The residue was dissolved in dry ether (50 ml), and the resulting solution was dropwise added to 70 % aqueous ethylamine (6.2 ml) while cooling with ice. The reaction mixture was gradually returned to room temperature and stirred for 1 hour. The ether layer was separated and concentrated to remove ether. The residue was purified by silica gel chromatography (eluent: ethyl acetate) to give N-ethylaminoxyacetamide (1.2 g). Yield, 31 %. Reference Example 3 Production of 4-(3,5-dichloropyridyl-2-oxy)phenol:- A suspension of 2,3,5-trichloropyridine (20 g), hydroquinone (25 g) and calcium carbonate (60 g) in dry dimethylsulfoxide (40 ml) was stirred at 90°C for 6 hours. To the reaction mixture, ether (300 ml) was added, and insoluble materials were removed by filtration. The filtrate was washed with 4 % aqueous ammonium chloride, followed by removal of ether by distillation. The residue was purified by silica gel chromatography (eluent: 20 % ethyl acetate : 80 % n-hexane) to give 4-(3,5-dichloropyridyl-2-oxy)phenol (17 g). Yield, 61 %. Reference Example 4 Production of ethyl 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionate:- A suspension of 4-(3,5-dichloropyridyl-2-oxy)phenol (17 g), ethyl DL-2-bromopropionate (13.2 g) and potassium carbonate (12.7 g) in dry methylethylketone (40 ml) was stirred under reflux for 4 hours. After removal of insoluble materials by filtration, the filtrate was concentrated by distillation. The residue was dissolved in dichloromethane, washed with water and concentrated by distillation to remove dichloromethane. The residue was purified by silica gel chromatography (eluent: 2 % ethyl acetate : 98 % n-hexane) to give ethyl 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionate (21.4 g). Yield, 95 %). Reference Example 5 Production of 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionic acid:- A solution of ethyl 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionate (21.4 g) and potassium hydroxide (5.3 g) in ethanol (60 ml) was stirred at room temperature for 1 hour. After removal of ethanol by distillation, the residue was combined with distilled water and made acidic with aqueous hydrochloric acid. The precipitate was collected by filtration and dried to give 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionic acid (19.8 g). Yield, 96 %. Reference Example 6 Production of ethyl 2-(4-hydroxyphenoxy)propionate:- A suspension of hydroquinone (12.2 g), ethyl DL-2-bromopropionate (10 g) and potassium carbonate (50 g) in methylethylketone (100 ml) was stirred under reflux for 5 hours. After removal of insoluble materials by filtration, the filtrate was concentrated by distillation. The residue was dissolved in ethyl acetate, washed with 5 % aqueous hydrochloric acid and concentrated to remove ethyl acetate. The residue was purified by silica gel chromatography (eluent: 20 % ethyl acetate : 80 % n-hexane) to give ethyl 2-(4-hydroxyphenoxy)propionate (3.0 g). Yield, 26 %. Reference Example 7 Production of ethyl 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionate:- A suspension of ethyl 2-(4-hydroxyphenoxy)propionate (3.0 g), 2,3,5-trichloropyridine (2.6 g) and potassium carbonate (3.9 g) in dry dimethylsulfoxide (5 ml) was stirred at 90°C for 5 hours. After removal of insoluble materials by filtration, ether (100 ml) was added thereto. The resultant organic layer was washed with 5 % aqueous hydrochloric acid and concentrated to remove ether. The residue was purified by silica gel chromatography (eluent: 2 % ethyl acetate : 98 % n-hexane) to give ethyl 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionate (2.4 g). Yield, 49 %. Reference Example 8 Production of 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propionic acid:- Into a mixture of methanol (10 ml) and tetrahydrofuran (14 ml), methyl 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propionate (0.6 g) was dissolved, and 1N sodium hydroxide solution (2.5 ml) was added thereto. The reaction was carried out at room temperature while stirring for 2 hours. After removal of methanol and tetrahydrofuran by distillation, the aqueous layer was washed with dichloromethane (1 ml), made acidic with conc. hydrochloric acid and extracted with ethyl acetate. The extract was concentrated to remove ethyl acetate to give 2-[4-(6-chloro-2-quinoxalinyloxy)phenoxy]propionic acid (0.44 g). Yield, 76 %. Example 1 Production of N-methoxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 38):- A mixture of 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionic acid (11 g), methyl aminoxyacetate (hydrochloride) (4.7 g) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (hydrochloride) (hereinafter referred to as "EDC-HCl") (12.9 g) in dry dichloromethane (15 ml) was stirred at room temperature for 2 hours. The reaction mixture was washed with water and concentrated. The residue was crystallized from a mixture of ethyl acetate and n-hexane to give N-methoxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (10.4 g). Yield, 75 %. Example 2 Production of N-ethylcarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 3):- A mixture of 2-[4-(3,5-dichloropyridyl-2-oxy)phenoxy]propionic acid (1 g), N-ethylaminoxyacetamide (0.43 g) and EDC-IICl (1.2 g) in dry dichloromethane (10 ml) was stirred at room temperature for 2 hours. The reaction mixture was washed with water and concentrated. The residue was crystallized from a mixture of dichloromethane and n-hexane to give N-ethylcarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (1.2 g). Yield, 90 %. Example 3 Production of N-hydroxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 37):- Into a mixture of 1N aqueous sodium hydroxide solution (48 ml) and methanol (300 ml), N-methoxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 38 as obtained in Example 1) (9.4 g) was dissolved, and the resultant mixture was stirred at 50°C for 1 hour. After removal of methanol by distillation, the aqueous layer was made acidic with conc. hydrochloric acid and extracted with ethyl acetate. Removal of the ethyl acetate from the extract by distillation gave N-hydroxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (9.0 g). Yield, 98 %. Example 4 Production of N-piperidinocarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 14):- A mixture of N-hydroxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 37 as obtained in Example 3) (0.7 g), 1-aminopiperidine (0.19 g) and EDC-HCl (0.67 g) in dry dichloromethane (5 ml) was stirred at room temperature for 2 hours. The reaction mixture was washed with water and concentrated. The residue was crystallized from a mixture of dichloromethane and n-hexane to give N-piperidinocarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (0.56 g). Yield, 73 %. Example 5 Production of N-methoxycarbonylmethoxy-N-methyl-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 48):- To a solution of N-hydroxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (Compound No. 37 as obtained in Example 3) (0.38 g) in methanol (1 ml), there was added an etheral solution of diazomethane until the yellow color remained, and the resultant mixture was allowed to stand for 10 minutes. The reaction mixture was concentrated under reduced pressure. The residue was purified by silica gel chromatography (eluent: 88 % hexane : 12 % ethyl acetate) to give N-methoxycarbonylmethoxy-N-methyl-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide (0.35 g). Yield, 86 %. In the same manner as above, there are produced the compounds as shown in Table 1. The ¹H-NMR (δ) data of the compounds as shown in Table 1 are given below. Compound No. 1 (CDCl₃): 1.54 (3H, d, J = 7.8 Hz), 4.30 (2H, s), 4.69 (1H, q, J = 7.8 Hz), 5.78 (2H, bs), 6.81 (2H, d, J = 9.0 Hz), 7.03 (2H, d, J = 9.0 Hz), 7.60 - 7.70 (1H, m), 7.80 - 7.90 (1H, m), 8.00 (1H, bs); Compound No. 2 (CDCl₃): 1.56 (3H, d, J = 7.4 Hz), 3.68 (3H, d, J = 4.4 Hz), 4.27 (2H, s), 4.74 (1H, q, J = 7.4 Hz), 6.81 (2H, d, J = 9.0 Hz), 7.03 (2H, d, J = 9.0 Hz) 7.60-7.70 (1H, m), 7.80-7.90 (1H, m), 8.00 (1H, bs), 9.63 (1H, bs); Compound No. 3 (CDCl₃): 1.12 (3H, t, J = 7.2 Hz), 1.69 (3H, d, J = 7.0 Hz), 3.10-3.57 (2H, m), 4.29(2H, s), 4.73 (1H, q, J = 7.0 Hz), 6.88 (2H, d, J = 9.0 Hz), 7.10 (2H, d, J = 9.0 Hz), 7.75 (1H, d, J = 2.0 Hz), 7.92 (1H, d, J = 2.0 Hz), 8.13 (1H, bs), 9.86 (1H, s); Compound No. 4 (CDCl₃): 0.93 (3H, t, J = 6.4 Hz), 1.40-1.76 (2H, m), 1.59 (3H, d, J = 6.6 Hz), 3.10-3.43 (2H, m), 4.30 (2H, s), 4.73 (1H, q, J = 6.6 Hz), 6.86 (2H, d, J = 9.0 Hz), 7.06 (2H, d, J = 9.0 Hz), 7.75 (1H, d, J = 2.0 Hz) 7.92 (1H, d, J = 2.0 Hz), 8.13 (1H, bs), 9.97 (1H, bs); Compound No. 5 (CDCl₃): 1.24 (3H, t, J = 7.6 Hz), 1.40-1.76 (4H, m), 1.59 (3H, d, J = 6.6 Hz), 3.10-3.43 (2H, m), 4.27 (2H, s), 4.71 (1H, q, J = 6.6 Hz), 6.86 (2H, d, J = 9.0 Hz), 7.06 (2H, d, J = 9.0 Hz), 7.60-7.70 (1H, m), 7.80-7.90 (1H, m), 8.01 (1H, bs), 9.77 (1H, s); Compound No. 6 (CDCl₃): 1.37 (9H, s), 1,58 (3H, d, J = 6.6 Hz), 4.13 (2H, s), 4.67 (1H, q, J = 6.6 Hz), 6.86 (2H, d, J = 9.0 Hz), 7.06 (2H, d, J = 9.0 Hz), 7.60-7.70 (1H, m), 7.33 (1H, bs), 7.80-7.90 (1H, m), 9.80 (1H, bs); Compound No. 7 (CDCl₃): 1.50-1.88 (9H, m), 1.58 (3H, d, J = 6.6 Hz), 4.21 (2H, s), 4.68 (1H, q, J = 6.6 Hz), 6.86 (2H, d, J = 9.0 Hz), 7.06 (2H, d, J = 9.0 Hz), 7.60-7.70 (1H, m), 7.00 (1H, bs), 7.80-7.90 (1H, m), 8.02 (1H, bs); Compound No. 8 (CDCl₃): 1.59 (3H, d, J = 6.6 Hz), 4.38 (2H, s), 4.76 (1H, q, J = 6.6 Hz), 6.83-7.90 (11H, m), 9.90 (1H, s), 10.23 (1H, bs); Compound No. 9 (DMSOd₆): 1.43 (3H, d, J = 6.6 Hz), 4.00-4.70 (2H, bs), 4.21 (2H, s), 4.65 (1H, q, J = 6.6 Hz), 6.80 (2H, d, J = 9.0 Hz), 7.00 (2H, d, J = 9.0 Hz), 7.97 (1H, d, J = 2.4 Hz), 8.11 (1H, d, J = 2,4 Hz), 9.17 (1H, s); Compound No. 10 (DMSOd₆): 1.42 (3H, d, J = 6.6 Hz), 1.73-1.89 (3H, m), 4,27 (1H, s), 4.60 (1H, s), 4.69 (1H, q, J = 6.6 Hz), 6.80 (2H, d, J = 9.0 Hz), 7.00 (2H, d, 3 = 9.0 Hz), 7.30 (1H, q, J = 5.4 Hz), 7.93-8.00 (1H, m), 8.10-8.17 (1H, m), 11.10-11.23 (1H, bs); Compound No. 11 (CDCl₃): 1.59 (3H, d, J = 6.6 Hz), 4,45 (2H, s), 4.74 (1H, q, J = 6.6 Hz), 6.79 (2H, d, J = 9.0 Hz), 6.71-8.23 (10H, m), 9.84 (1H, s), 10.18 (1H, bs); Compound No. 12 (CDCl₃): 1.60 (3H, d, J = 6.6 Hz), 4.43 (2H, s), 4.78 (1H, q, J = 6.6 Hz), 6.71-8.74 (11H, m), 10.63 (1H, s); Compound No. 13 (CDCl₃): 1.58 (3H, d, J = 6.6 Hz), 2.65-2.88 (4H, m), 3.70-3.85 (4H, m), 4.32 (2H, s), 4.71 (1H, q, J = 6.6 Hz), 6.81 (2H, d, J = 9.0 HZ), 7.01 (2H, d, J = 9.0 Hz), 7.66 (1H, d, J = 2.4 Hz), 7.83 (1H, d, J = 2.4 Hz), 7.85 (1H, bs), 9.28 (1H, s); Compound No. 14 (DMSOd₆): 1.33-1.50 (9H, m), 2.33-2.66 (4H, m), 4.11 (2H, s), 4.71 (1H, q, J = 7.2 Hz), 6.80 (2H, d, J = 9.0 Hz), 7.00 (2H, d, J = 9.0 Hz), 7.91-8.00 (1H, m), 8.11-8.19 (1H, m), 8.52 (1H, s), 8.90 (1H, s); Compound No. 15 (CDCl₃): 1.59 (3H, d, J = 6.6 Hz), 2.86 (3H, s), 2.89 (3H, s), 4,47 (2H, s), 4.68 (1H, q, J = 6.6 Hz), 6.82 (2H, d, J = 9.0 Hz), 7.01 (2H, d, J = 9.0 Hz), 7.93-8.00 (1H, m), 8.10-8.17 (1H, m), 10.09 (1H, bs); Compound No. 16 (CDCl₃): 0.87 (6H, t, J = 7.0 Hz), 1.23-1.69 (4H, m), 1.58 (3H, d, J = 6.6 Hz), 2.87-3.33 (4H, m), 4,50 (2H, s), 4.67 (1H, q, J = 7.0 Hz), 6.81 (2H, d, J = 9.0 Hz), 7.01 (2H, d, J = 9.0 Hz), 7.91-8.00 (1H, m), 8.11-8.19 (1H, m), 10.01 (1H, bs); Compound No. 17 (CDCl₃): 1.47-1.70 (4H, m). 1.57 (3H, d, J = 7.0 Hz), 4.47 (2H, s), 4.67 (1H, q, J = 7.0 Hz), 6.81 (2H, d, J = 9.0 Hz), 7.01 (2H, d, J = 9.0 Hz), 7.91-8.00 (1H, m), 8.11-8.19 (1H, m), 10.00 (1H, bs); Compound No. 18 (CDCl₃): 1.58 (3H, d, J = 6.8 Hz), 2.87-3.70 (8H, m), 4,47 (2H, s), 4.67 (1H, q, J = 6.8 Hz), 6.81 (2H, d, J = 9.0 Hz), 7.01 (2H, d, J = 9.0 Hz), 7.91-8.00 (1H, m), 8.11-8.19 (1H, m), 10.00 (1H, bs); Compound No. 19 (CDCl₃): 1.12 (3H, s), 1.23 (3H. s), 1.58 (3H, d, J = 7.0 Hz), 2.30-4.41 (6H, m), 4.51 (2H, s), 4.70 (1H, q, J = 7.0 Hz), 6.85 (2H, d, J = 9.0 Hz), 7.04 (2H, d, J = 9.0 Hz), 7.95-8.04 (1H, m), 8.15-8.23 (1H, m), 10.01 (1H, bs); Compound No. 20 (CDCl₃): 1.12 (3H, s), 1.23 (3H, s), 1.58 (3H, d, J = 7.0 Hz), 2.90-4.15 (6H, m), 4.51 (2H, s), 4.70 (1H, q, J = 7.0 Hz), 6.85 (2H, d, J = 9.0 Hz), 7.04 (2H, d, J = 9.0 Hz), 7.95-8.04 (1H, m), 8.15-8.23 (1H, m), 10.01 (1H, bs); Compound No. 21 (CDCl₃): 1.58 (3H, d, J = 7.0 Hz), 2.48-2.70 (3H, m), 3.46-3.88 (4H, m), 4.50 (2H, s), 4.67 (1H, q, J = 7.0 Hz), 6.84 (2H, d, J = 9.0 Hz), 7.01 (2H, d, J = 9.0 Hz), 7.91-8.00 (1H, m), 8.11-8.19 (1H, m), 10.01 (1H, bs); Compound No. 22 (CDCl₃): 1.59 (3H, d, J = 7.0 Hz), 2.27-2.50 (4H, m), 2.30 (3H, s), 3.23-3.63 (4H, m), 4.54 (2H, s), 4.78 (1H, q, J = 7.0 Hz), 6.87 (2H, d, J = 9.0 Hz), 7.05 (2H, d, J = 9.0 Hz), 7.63-7.77 (1H, m), 7.89-7.93 (1H, m), 9.27 (1H, bs); Compound No. 23 (CDCl₃): 1.24 (3H, t, J = 7.6 Hz), 1.57 (3H, d, J = 6.6 Hz), 4.14 (2H, q, J = 7.6 Hz), 4.41 (2H, s), 4.67 (1H, q, J = 6.6 Hz), 6.72-7.09 (4H, m), 7.61-7.67 (1H, m), 7.81-7.85 (1H, m), 9.59 (1H, bs); Compound No. 24 (CDCl₃): 0.91 (3H, t, J = 6.4 HZ), 1.12-1.79 (2H, m), 1.57 (3H, d, J = 6.0 Hz), 4.03 (2H, t, J = 6.2 Hz), 4.39 (2H, s), 4.65 (1H, q, J = 6.0 Hz), 6.68-7.12 (4H, m), 7.57-7.63 (1H, m), 7.76-7.80 (1H, m), 9.53 (1H, bs); Compound No. 25 (CDCl₃): 1.13 (3H, d, J = 6.0 Hz), 1.16 (3H, d, J = 6.0 Hz), 1.59 (3H, d, J = 6.6 Hz), 4.37 (2H, s), 4.66 (1H, dq, J = 6.0 Hz), 5.05 (1H, q, J = 6.6 Hz), 6.73-7.09 (4H, m), 7.62-7.67 (1H, m), 7.80-7.84 (1H, m), 9.59 (1H, bs); Compound No. 26 (CDCl₃): 0.94 (3H, t, J = 6.4 Hz), 1.00-1.76 (4H, m), 1.68 (3H, d, J = 6.2 Hz), 4.10 (2H, t, J = 6.0 Hz), 4.43 (2H, s), 4.69 (1H, q, J = 6.2 Hz), 6.77-7.00 (4H, m), 7.60-7.62 (1H, m), 7.79-7.84 (1H, m), 9.54 (1H, bs); Compound No. 27 (CDCl₃): 1.61 (3H, d, J = 6.6 Hz), 3.73 (3H, s), 4.48 (2H, s), 4.72 (1H, q, J = 6.6 Hz), 6.91 (2H, d, J = 9.0 Hz), 7.15 (2H, d, J = 9.0 Hz) 7.92-7.98 (1H, m), 8.18-8.25 (1H, m), 9.60 ((1H, bs); Compound No. 28 (CDCl₃): 1.61 (3H, d, J = 6.6 Hz), 2.85 (3H, d, J = 4.8 Hz), 4.38 (2H, s), 4.76 (1H, q, J = 6.6 Hz), 6.89 (2H, d, J = 9.0 Hz), 7.12 (2H, d, J = 9.0 Hz), 7.94-7.97 (1H, m), 8.04 (1H, bs), 8.19-8.24 (1H, m) 9.84 (1H, bs); Compound No. 29 (CDCl₃): 1.60 (3H, d, J = 7.2 Hz), 3.72 (3H, s), 4.47 (2H, s), 4.71 (1H, q, J = 7.2 Hz), 6.86-7.20 (5H, m), 7.80-7.99 (1H, m), 8.37-8.43 (1H, m), 9.64 (1H, bs); Compound No. 30 (CDCl₃): 1.60 (3H, d, J = 7.2 Hz), 2.70 (3H, d, J = 5.4 Hz), 4.28 (2H, s), 4.72 (1H, q, J = 7.2 Hz), 6.76-7.13 (5H, m), 7.75-7.93 (1H, m), 8.01 (1H, bs), 8.32-8.38 (1H, m), 9.92 (1H, bs); Compound No. 31 (CDCl₃): 1.15 (3H, t, J = 7.6 Hz), 1.55 (3H, d, J = 6.4 Hz), 3.05-3.54 (2H, m), 4.26 (2H, s), 4.68 (1H, q, J = 6.4 Hz), 6.73-8.50 (8H, m), 8.10 (1H, bs), 10.37 (1H, bs); Compound No. 32 (CDCl₃): 1.55 (3H, d, J = 6.4 Hz), 3.32-3.65 (8H, m), 4.55 (2H, s), 4.70 (1H, q, J = 6.4 Hz), 6.79-8.55 (9H, m), 9.45 (1H, bs); Compound No. 33 (CDCl₃): 3.76 (3H, s), 4.50 (2H, s), 4.54 (2H, s), 6.78-7.16 (4H, m), 7.67-7.70 (1H, m), 7.83-7.90 (1H, m), 9.60 (1H, bs); Compound No. 34 (CDCl₃): 2.82 (3H, d, J = 4.2 Hz), 4.34 (2H, s), 4.53 (2H, s), 6.83 (2H, d, J = 9.0 Hz), 7.04 (2H, d, J = 9.0 Hz), 7.66-7.69 (1H, m), 7.79-7.89 (1H, m), 8.09 (1H, bs); Compound No. 35 (CDCl₃): 3.78 (3H, s), 4.53 (2H, s), 4.57 (2H, s), 6.83-7.20 (4H, m), 7.91-7.97 (1H, m), 8.17-8.27 (1H, m), 9.60 (1H, m); Compound No. 36 (CDCl₃): 2.85 (3H, d, J = 4.8 Hz), 4.38 (2H, s), 4.57 (2H, s), 6.80-7.17 (4H, m) 7.90-7.97 (1H, m), 8.00 (1H, bs), 8.17-8.22 (1H, m), 9.97 (1H, bs); Compound No. 37 (DMSOd₆): 1.42 (3H, d, J = 6.6 Hz), 4.31 (2H, s), 4.66 (1H, q, J = 6.6Hz), 6.74-7.10 (4H, m), 7.93-8.00 (1H, m), 8.09-8.16 (1H, m), 10.00 (1H, bs); Compound No. 38 (CDCl₃): 1.59 (3H, d, J = 6.6 Hz), 3.69 (3H, s), 4.43 (2H, s), 4.67 (1H, q, J = 6.6 Hz) 6.73-7.09 (4H, m), 7.61-7.67 (1H, m), 7.80-7.85 (1H, m) 9.53 (1H, bs); Compound No. 39 (CDCl₃): 1.61 (3H, d, J = 6.4 Hz), 3.69 (3H, s), 4.46 (2H, s), 4.72 (1H, q, J = 6.4 Hz), 6.80-7.22 (4H, m), 7.51-7.52 (2H, m), 7.92-7.96 (1H, m), 8.56 (1H, s), 9.66 (1H, bs); Compound No. 40 (CDCl₃-CD₃OD): 1.58 (3H, d, J = 6.4 Hz), 4.38 (2H, s), 4.69 (1H, q, J = 6.4 Hz), 6.81-7.10 (5H, m), 7.71-7.90 (1H, m), 8.24-8.33 (1H, m); Compound No. 48 (CDCl₃-TMS): 1.57 (3H, d, J = 6.8 Hz), 3.74 (3H, s), 4.10 (3H, s), 4.52 (2H, s), 4.76 (1H, q, J = 6.8 Hz), 7.05 (4H, s), 7.75 (1H, d, J = 2.4 Hz), 7.95 (1H, d, J = 2.4 Hz). As stated above, the heterocyclic oxy-phenoxyacetic acid derivative (I) shows a remarkable herbicidal activity against a variety of weeds without producing any material phytotoxicity to broad-leaved crop plants. It is advantageous that its toxicity to mammals including human beings is very low. Further, it shows a significant intergeneric selectivity on monocotyledonous plants. Accordingly, it is useful as a herbicide for agriculture. Examples of monocotyledonous weeds, which the heterocyclic oxy-phenoxyacetic acid derivative (I) can control, are barnyardgrass ( Echinochloa cruss-galli ), barnyardgrass ( Echinochloa oryzicola ), large crabgrass ( Digitaria ciliaris ), violet crabgrass ( Digitaria violascens ), green foxtail ( Setaria viridis ), giant foxtail ( Setaria faberi ), yellow foxtail ( Setaria glauca ), wild oats ( Avena fatua ), water foxtail ( Alopecurus aegualis ), annual bluegrass ( Poa annua ), water paspalum ( Paspalum thunbergii ), cogongrass ( Imperata cylindrica ), whiskeygrass ( Andropogon virginicus ), zebragrass ( Miscanthus sinensis ), etc. For the practical usage of the heterocyclic oxy-phenoxyacetic acid derivative (I) as the herbicide, it may be formulated with a conventional solid or liquid carrier(s) or diluent(s) into a conventional preparation form chosen from solutions, suspensions, emulsifiable concentrates, wettable powders, granules, dusts, aerosoles, pastes, fumigants, etc. The content of the heterocyclic oxy-phenoxyacetic acid derivative (I) as the active ingredient in such preparation form is normally within a range of about 0.5 to 90 % by weight, preferably about 20 to 70 % by weight. Examples of the solid carrier or diluent are talc, clay, kaolin, diatomaceous earth, calcium carbonate, potassium chlorate, potassium nitrate, etc. As the liquid carrier or diluent, there are exemplified water, alcohols, aromatic hydrocarbons, ethers, ketones, esters, etc. When desired, such an auxiliary agent as an emulfifier, a spreading agent, a dispersing agent, a suspending agent and a stabilizer may be incorporated into the herbicidal composition. Further, the composition may be used in combination with other herbicides, insecticides, fungicides, fertilizers, plant growth controlling agent, etc. The dosage of the heterocyclic oxy-phenoxyacetic acid derivative (I) may be appropriately decided. In general, however, it may be from about 1 to 50 grams, preferably from about 2 to 30 grams, per 10 acre. Practical embodiments of the herbicidal composition of the invention and its use are illustratively shown in the following Formulation Examples and Test Examples wherein parts and % are by weight. The compound number of the active ingredient corresponds to the one in Table 1. Formulation Example 1 (Solution) Ten parts of Compound No. 3, 70 parts of xylene and 20 parts of polyoxyethylene alkylaryl ether are uniformly mixed to obtain a solution containing 10 % of the active incredient. The solution thus obtained is diluted with water to a designated concentration for practical application. Formulation Example 2 (Wettable powder) Forty parts of Compound No. 5, 55 parts of kaolinite (zieclite), 2 parts of sodium alkylbenzenesulfonate and 3 parts of polyoxyethylene alkylaryl ether are mixed well and pulverized to obtain a wettable powder containing 40 % of the active incredient. The wettable powder thus obtained is diluted with water to a designated concentration for practical application. Formulation Example 3 (Granules) One part of Compound No. 8, 20 parts of bentonite, 77 parts of clay and 2 parts of sodium dodecylbenzene sulfonate are mixed well while being powdered. The mixture is then kneaded with about 20 parts of water, granulated and dried to obtain granules containing 1 % of the active ingredient. Test Example 1 Pre-emergence application in upland:- Seeds of barnyardgrass ( Echinochloa crus-galli ), southern crabgrass, smartweed, slender amaranth, corn, wheat, soybean, cotton, beet, rapeseed and tomato were sowed to a 5 mm depth in a square pot (7.1 x 7.1 cm) filled with field soil. The designated amount of the test compound was diluted with water and sprayed to the soil at a spray volume of 10 liters per acre. The test plants were cultivated in a greenhouse for 20 days, and the herbicidal activity to weeds and the phytotoxicity to crop plants were observed and evaluated according to the following criteria: Index Evaluation 5 Complete control 4 severe control 3 moderate control 2 mild control 1 slight control 0 No control The results are shown in Table 2. Test Example 2 Post-emergence application in upland:- Seeds of barnyardgrass ( Echinochloa crus-galli ), southern crabgrass, smartweed and slender amaranth were sowed to a 5 mm depth in a square pot (7.1 x 7.1 cm) filled with field soil and cultivated in a greenhouse for 7 days until germination of their second-leaves. The designated amount of the test compound was diluted with water and sprayed to the foliage of the test plants at a spray volume of 10 liters per acre The test plants were further cultivated in the greenhouse for 20 days and the herbicidal activity to weeds and the phytotoxicity to crop plants were examined in the same manner as in Test Example 1. The results are shown in Table 3. Test Compound No. Dosage (g/acre) Herbicidal activity (weed) Barnyardgrass Large crabgrass Smartweed Slender amaranth 1 40 5 5 0 0 2 40 5 5 1 2 3 40 5 5 2 2 4 40 5 5 0 1 5 40 5 5 0 2 6 40 5 5 0 0 7 40 5 5 0 0 13 40 5 5 0 0 14 40 5 5 0 0 15 40 5 5 16 40 5 5 2 1 17 40 5 5 0 0 18 40 5 5 22 40 5 5 0 0 27 40 5 5 0 0 28 40 5 5 0 0 31 40 5 5 2 3 32 40 5 5 0 2 38 40 5 5 0 0 (a) 40 5 5 3 5 (c) 5 5 5 0 0 (d) 20 5 5 0 2 Test Example 3 Post-emergence application in upland:- Seeds of wild oat, wheat, water foxtail and annual bluegrass were sowed to a 5 mm depth in a square pot (7.1 x 7.1 cm) filled with field soil and cultivated in a greenhouse kept at 10 to 15°C for 3 weeks. The designated amount of the test compound was diluted with water and sprayed onto the foliage of the test plants at a spray volume of 10 L/acre. The test plants were further cultivated in the greenhouse for 3 to 4 weeks and the herbicidal activity was examined in the same manner as in Test Example 1. The results are shown in Table 4. Test Example 4 Pre-emergence application in paddy field:- Seeds of barnyardgrass ( Echinochloa oryzicola ) and monochoria sowed in a square pot (7.1 x 7.1 cm) filled with paddy field soil, and water was poured therein to make a flooded condition. A designated test compound diluted with water was applied to the pot by perfusion, and the test plants were cultivated in a greenhouse for 20 days. The herbicidal activity was examined in the same manner as in Test Example 1. The results are shown in Table 5. Test Example 5 Post-emergence application in paddy field:- Seeds of barnyardgrass ( Echinochloa oryzicola ) and monochoria sowed in a square pot (7.1 x 7.1 cm) filled with paddy field soil. Water was poured therein to make a flooded condition, and the test plants were cultivated in a greenhouse for 7 days until emergence of the second-leaves. A designated test compound diluted with water was applied to the pot by perfusion, and the test plants were grown in the greenhouse for 20 days. The herbicidal activity was examined in the same manner as in Test Example 1. The results are also shown in Table 5. Test Compound No. Dosage (g/acre) Pre-emergence treatment Post-emergence treatment Barnyardgrass Monochoria Barnyardgrass Monochoria 2 40 5 3 5 2 3 40 5 3 5 3 4 40 5 3 5 3 15 40 5 3 5 3 16 40 5 1 5 0 18 40 5 3 5 2 38 40 5 4 5 4

Claims: Claims for the following Contracting States : AT, BE, CH, DE, DK, FR, GB, IT, LI, LU, NL, SE A heterocyclic oxy-phenoxyacetic acid derivative of the formula: wherein R is a pyridyl or quinoxalinyl group optionally bearing thereon not more than two substituents chosen from halogen and halo(lower)alkyl; R¹ and R² are each hydrogen or lower alkyl; R³ is -NR⁴R⁵, -NHR⁶ or -OR⁷ (in which R⁴ and R⁵ are each hydrogen or lower alkyl or, when taken together with the adjacent nitrogen atom, represent a saturated nitrogen-containing 5- or 6-membered heterocyclic group optionally having one additional ring hetero atom chosen from nitrogen, oxygen and sulfur, which may bear thereon not more than two lower alkyl groups; R⁶ is lower cycloalkyl, substituted or unsubstituted aryl, or a saturated or unsaturated 5- or 6-membered heterocyclic group having at least one ring hetero atom chosen from nitrogen, oxygen and sulfur or a group of the formula: -NR⁸R⁹ (in which R⁸ and R⁹ are each hydrogen or lower alkyl or, when taken together, represent a lower alkylidene group); and R⁷ is hydrogen, lower alkyl, lower alkoxy, substituted or unsubstituted aryl(lower)alkyl, substituted or unsubstituted aryloxy(lower)alkyl, halo(lower)alkyl, hydroxy(lower)alkyl or lower alkoxy(lower)alkyl), wherein the term "lower" means a group having not more than 8 carbon atoms, or its salt. A compound as claimed in Claim 1 which is: N-methoxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; N-ethylcarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; N-hydroxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; N-piperidinocarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; or N-methoxycarbonylmethoxy-N-methyl-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide. A process for the production of a compound as claimed in Claim 1 or Claim 2 which comprises reacting a compound of the formula: wherein R and R¹ are as defined, in Claim 1, or a reactive derivative thereof, with an amine of the formula: wherein R² and R³ are as defined in Claim 1. A process for the production of a compound as claimed in Claim 1 or Claim 2 which comprises the steps of: (a) reacting a compound of the formula: wherein R and R¹ are as defined in Claim 1 with NH₂OH in the presence of a base to produce a compound of the formula: wherein R and R¹ are as defined in Claim 1: and (b) reacting the resultant compound (IV) with a compound of the formula: X-CH₂ COOR¹⁰ wherein R¹⁰ is lower alkyl and X is halogen, to produce a compound of the formula: wherein R and R¹ are as defined in Claim 1 and R¹⁰ is as defined above, optionally followed by either (c) hydrolysis of the resultant compound (I′) with an alkali to produce a compound of the formula: which is optionally followed by (d) reacting the resultant compound (I″) with wherein R⁴ and R⁵ are as defined in Claim 1 to produce a compound of the formula: or (e) reacting the resultant compound (I′) from step (b) with an alkylating agent to produce a compound of the formula: wherein R,R¹,R² and R¹⁰ are as defined above. A herbicidal composition which comprises at least one compound as claimed in Claim 1 or Claim 2, and one or more carriers or diluents. A method for controlling weeds in a field of crop plant, which comprises applying at least one compound as claimed in Claim 1 or Claim 2 to the field. A method as claimed in Claim 6 wherein the compound is applied in an amount of from about 1 to 50g, and preferably from about 2 to 30g per 10 acre. The use of a compound as claimed in Claim 1 or Claim 2 as a herbicide. Claims for the following Contracting States : GR, ES A process for the production of a herbicidal composition which comprises admixing at least one heteroyclic oxy-phenoxy acetic acid derivative of the formula: wherein R is a pyridyl or quinoxalinyl group optionally bearing thereon not more than two substituents chosen from halogen and halo(lower)alkyl; R¹ and R² are each hydrogen or lower alkyl; R³ is -NR⁴R⁵, -NHR⁶ or -OR⁷ (in which R⁴ and R⁵ are each hydrogen or lower alkyl or, when taken together with the adjacent nitrogen atom, represent a saturated nitrogen-containing 5- or 6-membered heterocyclic group optionally having one additional ring hetero atom chosen from nitrogen, oxygen and sulfur, which may bear thereon not more than two lower alkyl groups; R⁶ is lower cycloalkyl, substituted or unsubstituted aryl, or a saturated or unsaturated 5- or 6-membered heterocyclic group having at least one ring hetero atom chosen from nitrogen, oxygen and sulfur or a group of the formula: -NR⁸R⁹ (in which R⁸ and R⁹ are each hydrogen or lower alkyl or, when taken together, represent a lower alkylidene group); and R⁷ is hydrogen, lower alkyl, lower alkoxy, substituted or unsubstituted aryl(lower)alkyl, substituted or unsubstituted aryloxy(lower)alkyl, halo(lower)alkyl, hydroxy(lower) alkyl or lower alkoxy(lower)alkyl), wherein the term "lower" means a group having not more than 8 carbon atoms, or its salt, with one or more carriers or diluents A process for the production of a compound as defined in Claim 1 which comprises reacting a compound of the formula: wherein R and R¹ are as defined in Claim 1, or a reactive derivative thereof, with an amine of the formula: wherein R² and R³ are as defined in claim 1. A process for the production of a compound as defined in Claim 1 which comprises the steps of: (a) reacting a compound of the formula: wherein R and R¹ are as defined in claim 1 with NH₂OH in the presence of a base to produce a compound of the formula: wherein R and R¹ are as defined in claim 1: and (b) reacting the resultant compound (IV) with a compound of the formula: X-CH₂ COOR¹⁰ wherein R¹⁰ is lower alkyl and X is halogen, to produce a compound of the formula: wherein R and R¹ are as defined in Claim 1 and R¹⁰ is as defined above, optionally followed by either (c) hydrolysis of the resultant compound (I′) with an alkali to produce a compound of the formula: which is optionally followed by (d) reacting the resultant compound (I″) with wherein R⁴ and R⁵ are as defined in Claim 1 to produce a compound of the formula: or (e) reacting the resultant compound (I′) from step (b) with an alkylating agent to produce a compound of the formula: wherein R,R¹,R² and R¹⁰ are as defined above. A process as claimed in claim 2 or claim 3 wherein the starting materials are chosen such that the resultant compound is; N-methoxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy] propionamide; N-ethylcarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; N-hydroxycarbonylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; N-piperidinocarbamoylmethoxy-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide; or N-methoxycarbonylmethoxy-N-methyl-2-[4-(3,5-dichloro-2-pyridyloxy)phenoxy]propionamide. A method for controlling weeds in a field of crop plant, which comprises applying a herbicidally effective amount of a compound as defined in Claim 1 to the field. A method as claimed in claim 5 wherein the compound is applied in an amount of from about 1 to 50g, and preferably from about 2 to 30g per 10 acre. The use of a compound as defined in claim 1 as a herbicide.

Inventors: HAYASE YOSHIO, IDE KINYA, KAMEI KAZUO, MATSUMOTO KOHEI, TAKAHASHI TOSHIO, HAYASE, YOSHIO, IDE, KINYA, KAMEI, KAZUO, MATSUMOTO, KOHEI, TAKAHASHI, TOSHIO
Applicants: SHIONOGI & CO, SHIONOGI SEIYAKU KABUSHIKI KAISHA
Application year: 1990
Main classification: C07D213
IPC codes: C07D213, A01N43, C07D401, C07D413, C07D403, C07D405, C07D241