KR960003323B1 - NOVEL HERBICIDAL PYRIMIDIN DERIVATIVES HAVING Ñß-CARBONYLIMINO STRUCTURE, THE PROCESS FOR PREPARATION THEREOF AND THE HERBICIDES CONTAING THE SAME - Google Patents

Abstract

Novel alpha-carbonyl imino ester derivs. of 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl)oxy benzoic acid or its isomer are prepd. by reacting a cpd. of formula (III) and a cpd. of formula (IV) in the presence of solvent and metallic salt. In the formulas, R1 is C1-8 straight alkyl, C3-5 branched alkyl, cyclo alkyl, propenyl, lower alkoxy, lower alkylthio, phenyl sustd. lower alkyl, amino to be can substd. with H, halogen, one or two methyl or C1-4 alkyl, lower alkoxy, lower alkoxy alkyl, lower haloalkyl, or aryl substd. phenyl to can form acetal; R2 is methyl, C1-8 straight or branched alkoxy, propenylalkoxy, methoxy to be substd. with phenyl, furanyl, thiofuranyl or pyranyl, amino to be can substd. with C1-4 alkyl, or amine deriv. to be derived from amino acid ester or amino acid.

Description

Novel herbicidal pyrimidine derivatives having α-carbonylimino structures, preparation methods thereof, and herbicides

The present invention provides a novel herbicidal pyrimidine derivative represented by the following general formula (I), more specifically, new 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid Α-carbonyl imino ester derivatives or isomers thereof, methods for their preparation and their use for combating plants harmful to crops.

Wherein R ¹ is a straight, branched or cycloalkyl group having a saturated or unsaturated bond having 1 to 10 carbon atoms; Lower alkyl groups substituted with one or two or more groups selected from the group consisting of lower alkoxy, lower alkylthio and phenyl groups; Hydrogen atom, halogen atom, C ₁ -C ₄ alkyl group, C ₁ -C ₄ alkoxy group, amino group which may be substituted with C ₁ -C ₄ alkyl group, lower alkoxyalkyl group, lower haloalkyl group, which may form acetal A phenyl group which can be substituted by one or two or more groups selected from the group consisting of an acyl group and a phenyl group; R ² is an alkyl group of C ₁ -C ₄ ; Saturation of a straight or branched C ₁ -C ₈ which is releasable with a 5 or 6 membered aromatic ring or heterocyclic ring which may contain one or more heteroatoms in the ring, such as phenyl, furanyl, thiofuranyl and pyranyl groups Or an unsaturated alkoxy group; Or an amino group substitutable for an alkyl group of C ₁ -C ₄ ; Amine derivatives derived from esters of amino acids or amino acid amides.

In the present specification, the term "alkyl" is used to mean all saturated or unsaturated hydrocarbons unless otherwise specified, and represents straight chain alkyl or branched chain or cycloalkyl; "Lower" means containing 1 to 6 carbon atoms in the atom group. In addition, in the compound according to the present invention, the E-isomer and the Z-isomer may exist respectively or together around the amino group.

Examples of preferred "alkyl groups" in the substituent definition of general formula (I) include methyl, ethyl, vinyl, propyl, isopropyl, allyl, n-butyl, sec-butyl, t-butyl, isobutyl, pentyl, n-hexyl , Isohexyl, cyclopropyl, cyclohexyl or octyl group and most preferably methyl, ethyl, propyl, or isopropyl.

Examples of preferred "lower alkyl" are methyl, ethyl, propyl, isopropyl, butyl, or isobutyl groups.

Examples of preferred “alkoxy groups” include methoxy, ethoxy, propoxy, isopropoxy, allyloxy, n-butoxy, sec-butoxy, t-butoxy, isobutoxy, pentyloxy, n-hexyloxyl, Isohexyloxy, cyclohexyloxy or octyloxy groups and the like, most preferably methoxy, ethoxy, propoxy or isopropoxy.

Examples of preferred "lower alkoxy" are methoxy, ethoxy, propoxy, isopropoxy or allyloxy groups.

Examples of preferred "lower alkoxyalkyls" are methoxymethyl or ethoxymethyl groups, and examples of preferred "lower haloalkyls" are trifluoromethyl groups.

Examples of preferred “acyl” are acetyl or 1,1-ethylenedioxyethyl groups.

Examples of preferred "amino groups" are dimethylamino, ethylamino, isopropylamino or t-butylamino groups, and examples of preferred "amine derivatives" are methoxycarbonylmethylamino, ethoxycarbonylmethylamino, 1-methoxycarbon Nyl-2-phenylethylamino, 1,1-di (ethoxycarbonyl) methylamino, 1,2-di (methoxycarbonyl) ethylamino or 2-carbamoyl-3-methylbutan-2-yl amino group And so on.

2-phenoxy pyrimidine or (pyrimidin-2-yl) oxybenzene derivatives are well known to be useful as herbicides (Agr. Biol. Chem., Vol. 30, P.896 (1966), Japanese Patent Laid-Open 79-55729). In particular, among the compounds recently developed based on 2-phenoxypyrimidine, it has been found that derivatives of 2- (pyrimidin-2-yl) oxybenzoic acid show excellent herbicide effects (European Patent Publication). 233,406, 249,708, 287,072, 287,79, 315,889, 321,846, 330,990, 335,409, 335,409, 346,789, 363,040, 402,751, 435,170, 435,186, 457,505, 459,243, 468,690, British Patent 2,237,570, and German Patent 3,942,476).

These known compounds show a similar mechanism of action to sulfonylurea derivatives, idazolidine derivatives, and triazolepyrimidine derivatives, which are well known as conventional amino acid biosynthesis inhibitors, and have the advantage of simplicity and ease of synthesis. Attention has been drawn to herbicides that inhibit amino acid biosynthesis of new structures. In addition, since these known compounds have a basic functional mechanism of 2- (pyrimidin-2-yl) oxybenzoic acid alone, which inhibits amino acid biosynthesis, ester derivatives of these benzoic acids are hydrolyzed by appeals in plants. It is also well known to be a pro-herbicide that is converted to 2- (pyrimidin-2-yl) oxybenzoic acid to exhibit herbicidal efficacy (see Pestic. Sci., Vol. 31, P. 305 (1991)).

The benzoic acid derivatives in which the 2 and 6 positions are substituted are structural features such that the carboxyl group is perpendicular to the phenyl ring under the influence of the substituents, which causes the carboxyl group to be severely disturbed in reaction with other nucleophiles. For this reason, the esterification of the benzoic acid derivatives substituted with the 2, 6 positions is subject to many limitations, and the reaction yield is not good.

On the other hand, compounds developed based on 2- (pyrimidin-2-yl) oxybenzoic acid must be substituted for the "6" position in order to express excellent efficacy. Representative of these substituents are halogen (Cl, F, etc.), alkoxy, phenoxy and the like. However, as mentioned above, since the benzoic acid ester derivatives substituted at the 2 and 6 positions are less responsive to the hydrolysis reaction, their ester derivatives do not have effective herbicidal power.

These results can be well confirmed through the herbicidal assay and the enzyme reaction rate analysis using ALS (Acetolactate Synthase) enzyme to be shown in the following experimental example.

In view of this situation, the present inventors have found that 2- (pyrimidin-2-yl) oxybenzoic acid having a substituent at the “6” position in order to develop a herbicide having more excellent amino acid biosynthesis and less harmful to crops. At the same time, the need to find new derivatives that are not only pro-herbicide properties but also excellent herbicides by themselves is found.

The present invention provides α-carbonyl imino ester derivatives of novel 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid represented by the following general formula (I) do.

Wherein R ¹ and R ² are as described above.

These derivatives were found to be excellent herbicides in themselves, unlike the fact that known ester derivatives were Pro-herbicides as a result of measuring biosynthesis inhibition using ALS enzyme (Experimental Example 7).

Since the compound of the general formula (I) according to the present invention is characterized by comprising an imino ester of 2-chloro-6- (pyrimidin-2-yl) oxybenzoic acid, In order for the pyrimidin-2-yl) oxebenzoic acid derivatives to show strong herbicidal efficacy, substituents (especially chloro) are needed at the "6" position. In this case, however, the synthesis of imino ester derivatives may be problematic due to its structural characteristics. Thus, it is known that the imino ester derivatives of general 2- (pyrimidin-2-yl) oxybenzoic acid are free of substituents at the "6" position. For example, European Patent Publication No. 346,789 only describes simple imino ester derivatives using oximes made from acetone, cyclohexyl, cyclopentyl and the like, but there is no mention of their synthesis method and weed control efficacy. Thus, the present invention is a distinct and more advanced technology from these prior arts.

In addition, the compound (I) of the present invention not only shows superior herbicidal effect to flower weeds and broadleaf weeds or annual weeds and perennial weeds, but also exhibits no harmful to cotton, wheat and rice at the control concentrations of these weeds. Turned out to be a great herbicide.

Therefore, the α-carbonyl imino ester derivative of the general formula (I) according to the present invention shows high activity herbicidal power against harmful plants without harm to cultivated crops under field or paddy field conditions, especially in cotton and cultivated areas. It is useful for combating harmful plants.

Representative examples of α-carbonyl imino ester derivatives of 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid represented by Formula (I) according to the present invention Are listed in Table 1 below. Herein, the E-isomer and the Z-isomer may exist respectively or together around the imino group. Therefore, all such isomers are included in the scope of the present invention.

TABLE 1

As in the general formula (I) in the present invention, the '2, 6' positions of the benzoic acid are substituted, and the carboxylic acid group is steeply concealed in three dimensions. Therefore, these iminooxy ester derivatives cannot be synthesized in high yield according to conventional methods (Tetrahedron, Vol. 36, P. 2409 (1980), J. Org. Chem., Vol. 35, 1198 (1970). )Reference). Moreover, the esterification reaction of benzoic acid when stericly concealed is generally not very useful for the synthesis of the compound of the present invention because of strong acidic conditions.

In order to overcome this point, the compound (I) of the present invention utilizes a novel 2- (or 4-) mercapto pyridine ester represented by the following structural formula (III) as an important intermediate.

2- (or 4-) mercapto pyridine ester of formula (III) is 2-chloro-6-[(4,6-dimethoxypyri) represented by the following general formula (II) according to Scheme (1) Mijin-2-yl) oxy] benzoic acid can be prepared by reacting with 2, 2'-dipyridyl disulfide or 4, 4'-dipyridyl disulfide in the presence of trialkyl or triphenylphosphine and solvent (hereinafter Compounds of general formula (III) are represented by compound (IIIa) when 2-mercapto pyridine ester and compound (IIIb) when 4-mercapto pyridine ester).

Reaction Scheme (1)

The compound represented by general formula (II) can be synthesize | combined according to a well-known method (European patent publication 249,708). In the scheme (1), the solvent may be acetone, toluene, benzene, ether, ethyl acetate, CH ₂ Cl ₂ CHCl ₃ , CH ₂ ClCH ₂ Cl and the like.

The compound of formula (I) according to the present invention reacts the compound of formula (III) and the compound of formula (IV) with or without copper salt in a solvent according to Scheme (2) It can be prepared by soaking.

Reaction Scheme (2)

Wherein R ¹ and R ² are each as described above.

In the reaction scheme (2), the reaction in the presence of a copper salt is a room temperature or a low temperature reaction. Preferred solvents are halogenated hydrocarbons such as CH ₂ Cl ₂ , CHCl ₃ , CCl ₄ , CH ₂ ClCH ₂ Cl, or CH ₃ CN, CH ₃ CH. Copper (II) salts, such as CuBr ₂ and CuCl ₂ , are preferable in a high temperature reaction in which a solvent having a high boiling point, such as ₂ CN and xylene, does not use a copper salt. The α-carbonyl oxime compound of formula (IV) is easily synthesized according to a known method, and there are two main methods. First, Keto compound (V) of general formula (V) can be obtained by reacting with hydroxylamine (NH ₂ OH) according to the following Reaction Scheme (3). Second, according to the following Scheme (4) can be obtained by reacting the alkyl nitrile with acidic conditions from the compound (VI) having an acyl group.

Reaction Scheme (3)

Reaction Scheme (4)

Wherein R ¹ and R ² are each as defined above and R is lower alkyl, preferably ethyl or butyl.

Hereinafter, the present invention will be described in more detail with reference to Examples.

However, these examples are only intended to help the understanding of the present invention, but the invention is not limited thereto.

On the other hand, in the following examples, when the compound of the general formula (I) according to the present invention is obtained as both E and Z-isomers, for convenience, the compound obtained from the weakly polar hydroxyimine (IV) isomer on TLC is represented by " a ”was classified by attaching“ b ”to the compound number for the compound obtained from the highly polar hydroxyimine (IV) isomer.

[Production Example 1]

Synthesis of pyrimidin-2-yl thioester (III-a) of 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid

250 ml of toluene 31.0 g of 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid, 22.0 g of 2,2'-dipyridyl disulfides and 26.2 g of triphenyl phosphine Put in to vigorously stirred at room temperature for 3 hours. The reaction mixture is filtered and distilled under reduced pressure to remove toluene. The residue was chromatographed on silica gel to give 36.3 g (yield: 90%) of the title compound (III-a) as a white solid.

¹ H NMR (CDd ₃ , δ): 3.826 (6H, s), 5.794 (1H, s), 7.184 (1H, d), 7.3-7.4 (3H, m), 7.74 (2H, d), 8.60 (1H , d)

[Production Example 2]

Synthesis of pyrimidin-4-yl thioester (III) -b) of 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid

2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid 3.1 g 4, 4'-dipyridyl disulfide 2.2 and triphenyl phosphine 2.8 g in 20 ml of toluene Stir at room temperature for 2 hours. The reaction mixture is filtered and distilled under reduced pressure to remove toluene. The residue was chromatographed on silica gel to give 3.6 g (yield: 83%) of the title compound (III-b) as a white solid.

¹ H NMR (CDd ₃ , δ): 3.83 (6H, s), 5.81 (1H, s), 7.2-7.6 (5H, m), 8.64 (2H, d)

Example 1

[Synthesis of Compound (1) (R ₁ = CH ₃ , R ₂ = CH ₃ O)]

183 mg of the thioester compound (III-a) synthesized in Preparation Example 1 and 75 mg of 2-hydroxy imino propionic acid methyl ester were dissolved in 10 ml of xylene and refluxed for 30 minutes. Xylene was distilled off under reduced pressure, and then chromatographed on silica gel to give 43 mg (yield: 23%) of the title compound (1).

¹ H NMR (CDCl ₃ , δ): 2.15 (3H, s), 3.80 (6H, s), 3.98 (3H, s), 5.77 (1H, s), 7.20 (1H, d), 7.35 (1H, d ), 7.45 (1 H, t)

Example 2

[Synthesis of Compound (2) (R ₁ = CH ₃ , R ₂ = CH ₃ CH ₂ O)]

848 mg of the thioester compound (III-a) synthesized in Preparation Example 1 and 236 mg of 2-hydroxy imino propionic acid ethyl ester are dissolved in 5 ml of CH ₂ Cl ₂ . After adding 470 mg of CuBr ₂ while stirring the reaction solution at room temperature, the mixture was stirred for 1 hour. The reaction mixture was concentrated by filtration and chromatography on silica gel to give 486 mg (yield: 64%) of the title compound (2).

¹ H NMR (CDd ₃ , δ): 1.36 (3H, t), 2.14 (3H, s), 3.80 (6H, s), 4.35 (2H, q), 5.77 (1H, s), 7.20 (1H, d ), 7.35 (1H, d), 7.45 (1H, t)

MS (FAB): 424 (M + 1), 293

[Examples 3 to 28]

[Synthesis of Compounds (3) to (28)]

Compounds (3)-(28) can be synthesized by reacting thioester compound (III-a) or (III-b) with an appropriate hydroxyimino compound (IV) in a similar manner as in Example 2.

TABLE 2

Example 29

[Synthesis of Compound (29-a)]

404 mg of the thioester compound (III-a) synthesized in Preparation Example 1 and 195 mg of 2-hydroxyimino-2-phenylacetic acid methyl ester are dissolved in 5 ml of CH ₂ Cl ₂ . After adding 250 mg of CuBr ₂ while stirring the reaction solution at room temperature, the reaction solution is further stirred for 1 hour. The reaction mixture was chromatographed on silica gel to give 328 mg (yield: 69%) of the title compound (29-a).

¹ H NMR (CDCl ₃ , δ): 3.81 (6H, s), 3.91 (3H, s), 5.78 (1H, s), 7.21 (1H, d), 7.3-7.5 (5H, m), 7.67 (2H , d)

MS (FAB): 472 (M + 1), 293

[Examples 30 to 64]

[Synthesis of Compound (29-b) to Compound (56-b)]

The compound obtained by carrying out the method similar to Example 29 is shown in Table 3 below.

TABLE 3

Example 65

[Compound (57-a)]

252 mg of compound (56-a), 25 ml of tetrahydrofuran, 25 ml of methanol, 13 ml of water, 2 ml of con-HCl were added and stirred at room temperature for 20 hours. The solvent is distilled off under reduced pressure, extracted with ethyl acetate and washed with water. The separated organic layer is dried over magnesium sulfate and filtered. The solvent is distilled off under reduced pressure to obtain the desired compound (57-a) quantitatively.

¹ H NMR (CDCS) S ppm: 2.63 (3H, s), 3.82 (6H, s), 3.94 (3H, s), 5.79 (1H, s), 7.26-8.21 (7H, m) MS (FAB) m / e: 514 (M + 1), 293

Example 66

[Compound (57-b)]

252 mg of compound (56-b) is carried out in the same manner as in Example 65 to obtain a desired compound (57-b) in a rough manner.

¹ H NMR (CDCS) S ppm: 2.62 (3H, s), 3.74 (6H, s), 3.96 (2H, s), 5.73 (1H, s), 7.14-8.10 (7H, m) MS (FAB) m / e: 514 (M + 1), 293

Example 67

[Synthesis of Compound (58)]

404 mg of thioester compound (III-a) synthesized in Preparation Example 1 and 282 mg of 2-amino-3-phenylpropionic acid methyl ester) amide of 2-hydroxyimino propionic acid are dissolved in ₇ ml of CHCl ₂ . After adding 265 mg of CuBr ₂ while stirring the reaction solution at room temperature, the reaction solution was further stirred for 1 hour. The reaction mixture was chromatographed on silica gel to give 412 mg (yield: 74%) of compound (58).

¹ H NMR (CDCl ₃ , δ): 2.05 (3H, s), 3.13 (2H, m), 3.70 (3H, s), 3.72 (1H, d), 3.81 (6H, s), 4.86 (1H, m ), 5.79 (1H, s), 7.1-7.5 (8H, m)

MS (FAB): 557 (M + 1), 293, 154

Example 68-73

[Synthesis of Compounds (59) to (63)]

The compound obtained by carrying out the method similar to Example 67 is shown in Table 4 below.

TABLE 4

Α-carbonylimino ester derivatives of novel herbicidal 2-chloro-6-[(4,6-dimethoxy pyrimidin-2-yl) oxy] benzoic acid represented by the general formula (I) according to the present invention In order to test herbicidal efficacy, potted plants were treated with pot cultivation and treatment methods in greenhouses.

For the test, field weeds were Digitaria sanguinalis, Sataria farberi, Echinochgloa crus-galli var.caudata, Sorghum bicolor, Aeschynomene indica, Solanum migrum, Abutilon theophrasti, Calystegia japonica, Echinochgloa crus-galli var.oryzicola, Mantis grass (Aneilema Keisak), Scirpus jumcoides, Monarch chorus (Monochoria vaginalis) Cyperus difformis, sputum (Potamogeton disrinctus), peel grass (Sagittaria trifolia), oval (Eleocharis kuroguwai), cyperus serotins, and Olbi (Sagittaria pygmaea) were selected. And rice (Oryxa sativar) was selected.

When using the compound of the present invention, it is mixed with solid materials such as clay, activity, diatomaceous earth, water, alcohol, benzene, toluene, ether, ketones, esters, acids, amides, and liquid substances to form liquids, emulsions, emulsifiers, powders and granules. It may be formulated and used in any formulation such as, etc., wherein an emulsifier, a dispersing agent, a penetrating agent, a thickening agent, a stabilizer is added as necessary.

Next, although the compounding example of the herbicide which uses the compound of this invention as an active ingredient was shown, you should not limit this invention only to such an example.

[Formulation Example 1 (field conditions, 16g / ha)]

5 mg of the compound of the present invention was dissolved in 640 ml of an organic solvent (acetone), and then diluted in 640 ml of distilled water containing 0.2% of the nonionic surfactant Tween 20 to prepare a blend.

[Formulation Example 2 (field conditions, 16g / ha)]

5 mg of the compound of the present invention was dissolved in 320 ml of an organic solvent (acetone), and then diluted in 320 ml of distilled water containing 0.2% of the nonionic surfactant Tween 20 to prepare a blend.

TABLE 5

Experimental Example 1: Test for Weeding Prior to Germination and Crop Damage by Soil Treatment (Field Conditions)

After filling a rectangular plastic container (20 × 15 × 10cm) with sterilized field soil (sand loam, pH 5.5-6.0), sowing cotton with a surface area of 300cm ² and planting 8 weeds in one container And covered with 0.5 cm. After 1 day of watering, a portion (12 ml per plastic container) containing an active ingredient corresponding to the amount of treatment in the solution of Formulation Example 1 was placed on the soil surface

Spread evenly. For 30 days after the treatment, the herbicidal power against the plant cultivation and the observed weeds and the damage to the crops were evaluated according to the evaluation criteria.

TABLE 6

Experimental Example 2: Test of herbicidal power and drug weakness after germination by foliage treatment (field conditions)

After seeding the assay plants in the same manner as in Example 1 and cultivating for 10-14 days, when the plants reached the 3-4 leaf phase, a part containing the active ingredient corresponding to the amount of the treatment in Formulation Example 1 (12 ml per plastic container) Spray evenly on plant foliage. After 30 days of treatment, weeding and weed control against weeds and cultivation were observed according to evaluation criteria.

TABLE 7

Experimental Example 3: Test of herbicidal efficacy before germination by soil treatment (field conditions)

Fill the sterilized paddy soil (plow soil, pH 5.5-6.0) in each pot (30 × 15cm) and sow 10 species of rice and paddyweed in the soil with a surface area of 450cm ² and mix in soil. After one day of watering of 4 cm, a portion of the solution (12 ml per plastic container) containing the active ingredient corresponding to the treatment amount (16 g / ha) was dipped in the solution of Formulation Example 2. After 4 weeks of treatment and cultivation management and observation, herbicide effects on weeds against weeds and weeds were evaluated according to the criteria.

TABLE 8

Experimental Example 4: Control experiment of herbicidal efficacy during germination

According to known methods (European Patent Nos. 233,406, 249,708, 315,889), the compounds of Table 9 were synthesized, and the herbicidal efficacy against weeds was assayed according to the method of Experimental Example 1. As a result of the control experiment with known well-known drugs, it was confirmed that the novel derivative represented by the general formula (I) according to the present invention has excellent herbicidal effect.

TABLE 9

Experimental Example 5 Control Experiment of Herbicidal Effect During Germination

According to known methods (European Patent Nos. 223,406, 249,708 and 315,889), the compounds of Table 10 were synthesized, and the herbicidal efficacy against weeds was assayed according to the method of Experimental Example 1. As a result of the control experiment with known well-known drugs, it was confirmed that the novel derivative represented by the general formula (I) according to the present invention has excellent herbicidal effect.

TABLE 10

Experimental Example 7: biosynthesis inhibition experiment using ALS enzyme

(ALS = acetolactate synthase)

Taebaek rice cell line was harvested by suspension cul-ture under dark conditions using B-5 medium.

The callus was crushed in double buffer (20 mM KH ₂ PO ₄ , pH7.0, 0.1 mM Thiamine-Pyrophosphate, 0.5 mM Dithiothreitol, 1 μM MgCl ₂ , 10% w / v glycerol). The centrifuged solution is centrifuged for 30 minutes to take a supernatant. The ALS enzyme was precipitated in 25% -50% (NH ₄ ) ₂ SO ₄ solution, so that the precipitate was dissolved in the same buffer by centrifugation and used for enzyme analysis. The degree of biosynthesis was reacted for 30 minutes at 37 DEG C with a final volume of 1 ml, the acetolactate product was treated with an acid, and the acetoin obtained by decarboxylation was developed by the reaction of creatine with α-naphthol at 520 nm. Absorbance was measured. The analytical solution at this time includes 0.1M FAD, KH ₂ PO ₄ pH7.5 0.1mM thiamine-pyrophosphate, 1mM MgCl ₂ , 1μM FAD, 20mM pyruvic acid, an enzyme solution, and a synthetic herbicide of a predetermined concentration. The reaction is started by adding 20 ml of enzyme solution and 10 μl of 50% sulfuric acid solution is added to stop the reaction. Subsequently, the reaction solution to which sulfuric acid was added was heated at 60 ° C. for 15 minutes, and 200 μl of 0.5% creatine and 200 μl of 5% α-naphthol dissolved in 2.5N NaOH were added and developed at 37 ° C. for 30 minutes. The color reaction solution was centrifuged for 5 minutes to remove suspended solids, and the absorbance was measured at 520 nm. The I ₅₀ value can be defined as the concentration of the synthesized herbicide that inhibits ALS enzyme activity by 50% in the above method, which was calculated from the formula% activity = 100 / (1- [I] / I ₅₀ ).

Where [I] is the molarity of the synthetic herbicide.

TABLE 11

Claims (6)

(Alpha) -carbonyl imino ester derivative or isomer thereof of the novel 2-chloro-6-[(4,6-dimethoxypyrimidin-2-yl) oxy] benzoic acid represented by the following general formula (I). Wherein R ¹ is C _1-8 linear alkyl; C _3-5 branched alkyl; Cyclohexyl; Propenyl; Lower alkyl substituted with lower alkoxy, lower alkylthio or phenyl; Hydrogen, halogen. Phenyl group substituted by alkyl which may form amino, lower alkoxy, lower alkoxyalkyl, lower haloalkyl, phenyl, acetal which may be substituted by 1 or 2 methyl, C _1-4 alkyl, R ² is methyl ; C _1-8 straight or branched alkoxy; Propenyl alkoxy; Methoxy substituted with phenyl, purinyl, thiofuranyl or pyranyl; Amino substituted with C _1-4 alkyl; Amine derivatives derived from esters of amino acids or amino acid amides. A process for producing a compound of formula (I), wherein the compound of formula (III) is reacted with a compound of formula (IV) in the presence of a solvent or a metal salt. Wherein R and R ² are each as defined in claim 1. Novel 2-mercapto (or 4-mercapto) pyrimidine ester compound represented by the following structural formula (III). A compound of formula (III) as defined in claim 3, used as an intermediate for the preparation of compound of formula (I) as defined in claim 1. 2-chloro-6-[(4,5-dimethoxypyrimidin-2-yl) oxy] benic acid represented by the following general formula (II) was reacted with 2, in the presence of trialkyl or triphenylphosphine and a solvent; A process for preparing a 2 or 4-mercapto pyridine ester compound of the general formula (III) characterized by reacting with 2'-dipyridyl disulfide or 4, 4'-dipyridine disulfide. A herbicidal composition containing a herbicidally effective amount of the compound of formula (I) as defined in claim 1 together with a conventional carrier as an active ingredient.