JPS6225143B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel pyrazine derivative, and more particularly to a 2,3-dicyanopyrazine derivative, a method for producing the same, and a herbicide containing the compound as an active ingredient. According to the invention, the general formula [In the formula, A is a thienyl group, a furyl group, or a

[Formula] represents a group, and B represents a chlorine atom, a hydroxyl group, or a lower alkylamino group: Here, R ₁ represents a hydrogen atom or a lower alkoxy group, and R ₂ represents a nitro group, a trifluoromethyl group, or a carbamoyl group. , represents a cyano group or a lower alkoxy group, or R ₁ and R ₂ simultaneously represent a halogen atom. ] A 2,3-dicyanopyrazine derivative represented by the following is provided. A group of 2,3-dicyanopyrazine derivatives represented by the above general formula () are new compounds that have not been published in any literature, and are used for weeding, for example, for treating flooded soil in paddy fields, for treating foliage during the weed growing season, and for treating field soil. It has excellent herbicidal activity as an active ingredient of the agent, especially the following formula (
-3) [In the formula, A has the above meaning, and R ₃ represents a lower alkyl group. ] In paddy field flooded soil treatment, the compound shown generally tends to form a firm chemical treatment on the surface layer of the flooded paddy field.For example, it is virtually harmless to transplanted paddy rice, and is effective against annual weeds such as field weeds. It has the ability to control As described above, the 2,3-dicyanopyrazine derivative of the present invention can be used as an active ingredient in pre-emergence and/or post-emergence herbicides, and as a 2,3-dicyanopyrazine derivative of the above formula (-3), which has even better herbicidal activity. -5-
It is a compound that has high utility value as a synthetic intermediate for alkylaminopyrazine herbicides. The "lower alkoxy group" used in the above general formula () and the following description is a saturated aliphatic alkoxy group having 6 or less carbon atoms, preferably 3 or less carbon atoms, and most preferably a methoxy group. The "lower alkylamino group" represented by the general formula -NHR ₃ is a saturated aliphatic alkylamino group having 6 or less carbon atoms, preferably 4 or less carbon atoms. Further, the "halogen atom" includes fluorine, chlorine, bromine, and iodine, and among them, chlorine atom is preferred. When substituent A on the pyrazine ring is a substituted phenyl group, the substituent on the benzene nucleus is one or two halogen atoms, lower alkoxy groups, or nitro groups attached to the 3rd, 4th, and/or 5th positions. , a carbamoyl group, a cyano group or a trifluoromethyl group, provided that A does not represent a phenyl group substituted with only one halogen atom. Next, the method for producing the 2,3-dicyanopyrazine derivative of the present invention will be explained. The 2,3-dicyanopyrazine derivative (-1) of formula () when B represents a hydroxyl group is:
According to the present invention, diaminomaleonitrile of the following formula () and α-ketocarboxylic acid of the following formula () are combined by the following reaction formula: [In each of the above formulas, A has the above meaning. ] It can be produced by reacting according to the following. In addition, the compound of formula (-1) has the following formula (-1') due to tautomerism. [In the formula, A has the above meaning. ] However, in this specification, the compound is represented by the above formula (-1). The condensation reaction between the dianomaleonitrile of formula () and the α-ketocarboxylic acid of formula () can be carried out by bringing these two compounds into contact in the absence or in a solvent. The solvent is usually an inert solvent such as water; methanol,
Alcohols such as ethanol and propanol;
Ethers such as tetrahydrofuran, dioxane, and methyl cellosolve; organic acids such as formic acid and acetic acid; esters such as ethyl acetate and isopropyl acetate; nitriles such as acetonitrile and propionitrile, and the like can be used. Further, the above reaction is usually preferably carried out in the presence of a dehydration condensation catalyst, and examples of catalysts for dehydration condensation and ring closure that can be used at that time include inorganic acids such as hydrogen chloride, sulfuric acid, phosphoric acid, and nitric acid; formic acid, acetic acid, etc. or phosphorus halides such as phosphorus pentoxide, phosphorus pentachloride, phosphorus oxychloride, and phosphorus trichloride, preferably hydrogen chloride or acetic acid. The reaction temperature of the above condensation reaction is not critical and can vary widely depending on the reactants used;
Generally, it is preferable to use a temperature condition of 0°C to 200°C, particularly room temperature to 150°C. The proportions of the diaminomaleonitrile of the formula () and the α-ketocarboxylic acid of the formula () are not particularly restricted and can be varied widely as necessary. ) to the α-ketocarboxylic acid generally from 0.2 to 5, preferably from 0.7 to 2, most preferably approximately 1 (ie approximately equimolar). Under these conditions, this reaction can be completed within about 30 minutes to 5 hours, and the pyrazine derivative (-1) produced can be processed by means known per se, such as filtration, centrifugation, distillation, extraction, and chromatography. It can be separated and/or purified from the reaction mixture by means such as e.g., recrystallization, etc. Formula (-1) that can be obtained in this way
The halogenation of the 2,3-dicyano-5-hydroxypyrazine derivative can be carried out by treating the compound (-1) with a halogenating agent in the absence of a solvent or in an inert solvent. Suitable inert solvents that can be used include, for example, halogenated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride; aromatic hydrocarbons such as benzene, toluene, and xylene. Furthermore, as the halogenating agent, any of those often used to convert hydroxyl groups into halogen atoms can be used, such as phosphorus pentachloride,
Phosphorus pentahalides such as phosphorus pentabromide; phosphorus oxyhalides such as phosphorus oxychloride and phosphorus oxybromide; thionyl halides such as thionyl chloride are advantageously used. Although the amount of these halogenating agents used is not critical, it is generally advantageous to use them in an excess of at least an equivalent, preferably 1.5 to 20 equivalents, per mole of the compound of formula (-1). In particular, a halogenating agent that is liquid at room temperature, such as phosphorus oxychloride, may be used in large excess so that it also functions as a solvent. The above halogenation reaction is generally carried out under elevated temperature conditions ranging from room temperature to the reflux temperature of the reaction mixture.
Preferably, it can be carried out at a temperature of 50°C to reflux. Further, the halogenation reaction can be carried out in the presence of a tertiary amine such as pyridine, triethylamine, or N.N-dimethylaniline, if necessary, thereby promoting the reaction. Although the amount of the tertiary amine used is not critical, it can be used in an amount ranging from several percent by weight to approximately equimolar amount relative to the compound of formula (-1). Under such conditions, the halogenation reaction can usually be completed in about 1 to 5 hours. The 2,3-dicyano-5-halopyrazine derivative of formula (-2) obtained in this way can be obtained by adding a reaction mixture to the reaction mixture by means known per se, such as filtration, centrifugation, distillation, extraction, chromatography, recrystallization, etc. can be separated and/or purified from Next, formula (-2) produced as above
The compound of formula (-3) is obtained by reacting the 2,3-dicyano-5-halopyrazine derivative with an amine. This reaction can generally be carried out in an inert solvent such as ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; and hydrocarbons such as benzene, toluene and xylene. Although the reaction temperature is not critical and can vary widely depending on the type of reactants used, it is generally preferred to use relatively low temperatures of about 50°C or less, especially cooling conditions at or below room temperature. Advantageous to use. The amount of the amine to be used is also not particularly limited and can be varied over a wide range, but it can generally be used in an amount of approximately equimolar to a slight excess molar amount per mole of the compound of formula (-2). The reaction can advantageously be carried out in the presence of an acid binder, for example an inorganic or organic base such as sodium hydroxide, sodium carbonate, triethylamine.
Such an inorganic or organic base is usually advantageously used in an amount of at least 1 equivalent, preferably 1 to 2 equivalents, per mole of the compound of formula (-2). Further, by using the above-mentioned amine in large excess, the amine itself may simultaneously serve as an acid binding agent. The compound represented by formula (-3) thus obtained is separated from the reaction mixture by means known per se, such as filtration, distillation, extraction, chromatography, etc., or a combination thereof, and purified according to conventional methods. I can do it. The compound of formula () provided by the present invention has herbicidal activity and pharmacological activity, and is useful in fields such as agricultural chemicals and medicine. In particular, the compounds of the present invention have the ability to suppress the germination of weed seeds and/or kill the foliage of weeds, and can be used as active ingredients in pre-emergence herbicides and/or post-emergence herbicides in the treatment of flooded soil in paddy fields. It can be used for foliage treatment during the weed growing season, field soil treatment, etc., and can exhibit outstanding herbicidal effects. In particular, the compounds of the present invention exhibit excellent herbicidal activity in flooded paddy fields that are rich in water, and can be advantageously used as herbicides for paddy fields. This is thought to be because the compound of the present invention dissolves in water and is easily absorbed from the seeds, roots, and leaves of weeds in water, and directly acts on the germination inhibition, growth inhibition, and death of the weeds. Furthermore, the compounds of the present invention exhibit selective herbicidal activity and can effectively control noxious weeds. For example, the compound of the present invention has the ability to selectively weed out weeds, which are a typical weed of the same family Poaceae, without causing substantial damage to rice, through paddy field flooding soil treatment. Examples of weeds that can be controlled by the compound of the present invention include the following. (1) Paddy field weeds include, for example, Asteraceae (e.g., Asteraceae), Prunusaceae (e.g., Capsicum annuum, Absinaceae, Azetian azalea, Azena), Lythraceae (e.g., Lythrum, Lythrum, Lythrum), Lythraceae (e.g., Lythrum) ), Polygonaceae (e.g., water chickweed), Polygonaceae (e.g., Polygonaceae), Polygonaceae (e.g., willow knotweed), Chrysophyllaceae (e.g., Coccinaceae), Asteraceae (e.g., Asteraceae, Aquifoliaceae), Lemnaceae (e.g., Duckweed) , Hinjimo, Lemnacum), Cyperaceae (e.g., Hyderico, Firefly, Cyperus japonica, Cyperaceae), Poaceae (e.g., Poaceae, Noviaceae), Accipitridaceae (e.g., Sagittarius, Lemna), Cyperaceae (e.g., Helaophyllaceae), Adifoliaceae (e.g. Adifoliaceae), Porphyridaceae (e.g. Aomidae), etc. (2) Upland weeds include, for example, Chenopodiaceae (e.g., Coaxiaceae), Brassicaceae (e.g., shepherd's purse, Japanese radish, wild mustard), Amaranthaceae (e.g., Amaranthaceae),
Polygonaceae (e.g., Kishigigi, Hurtaceae), Rubiaceae (e.g., Caryophyllaceae), Caryophyllaceae (e.g., Caryophyllaceae, Chrysanthemum chinensis, Caryophyllaceae), Phosphoraceae (e.g., Prunus japonicus), Asteraceae (e.g., Harjiyon, Mugwort, Porphyra), Convolvulaceae (e.g. Convolvulaceae), Oxalis (e.g. Oxalis), Poaceae (e.g. Poaceae (e.g. Sparrow), Euphorbiaceae (e.g. Convolvulus), Solanaceae (e.g. Cyperaceae), Cyperaceae (e.g. : Kogomega Yatsuri) etc. When the compounds of the invention are used as herbicides, one or more combinations thereof may be used in combination with inert liquid or solid carrier materials or diluents commonly used in the herbicide field and, if necessary, It can be prepared by mixing it with additives such as surfactants and formulating it into an appropriate dosage form. As the carrier material or diluent that can be used in the herbicide of the present invention, any carrier material or diluent commonly used in the field can be used. Examples of the solid carrier material or diluent include kaolin, diatomaceous earth, talc, and bentonite. , montmorillonite, silica, clay, vermiculite, white carbon, kunilite (manufactured by Kunimine Kogyo Co., Ltd.), mica, gypsum, calcium carbonate, starch, plant powder, etc., and liquid carrier materials or diluents include For example, water, ethanol, cyclohexane, xylene, toluene, benzene, methylnaphthalene, kerosene, acetone, methyl ethyl ketone, cyclohexanone, isophorone, N/N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dioxane, ethylene glycol ethyl ether, liquefied tetrafluoroethane , ethyl acetate, butyl acetate, and the like. The herbicide of the present invention may contain a surfactant in a conventional amount depending on its dosage form, and examples of such surfactants include, for example, alkylbenzene sulfonate, lignin sulfonate, naphthalene sulfonate, formalin Condensate, dialkyl sulfosuccinate sodium salt, fatty acid salt, alkyl sulfate, higher alcohol sulfate ester, sorbitan fatty acid ester, polyalkylene glycol, polyoxyalkylene monoalkyl ether, polyoxyalkylene alkylaryl ether, polyoxyalkylene fatty acid ester, Polyoxyalkylene alkyl methyl captan ether, 4th
Ammonium salts and the like can be used alone or in combination of two or more. Therefore, the herbicide of the present invention generally contains at least 0.5% by weight of the active compound of formula (1), based on the weight of the herbicide, although it depends on its dosage form.
Preferably 1 to 99% by weight, more preferably 2 to 80% by weight
It can be included in a concentration of % by weight. Furthermore, the herbicide of the present invention can be formulated into any conventional dosage forms such as powders, granules, wettable powders, solutions, emulsions, and sprays, depending on the method of application. The formulation can be carried out by methods known per se in the art. For example, powders, granules and wettable powders can be prepared by mixing and grinding at least one active compound of formula () with at least one of the solid carrier materials or diluents mentioned above, adding an appropriate amount of surfactant; They can be mixed uniformly and formulated into a formulation. Solutions or emulsions can also be prepared by dissolving or dispersing at least one active compound of formula (1) in at least one of the above liquid carrier materials or diluents, and optionally adding a surfactant. Can be formulated into formulations. Thus, based on the weight of the herbicide, the active compound is present in concentrations of 2 to 30% by weight in the case of powders and granules and 5 to 60% in the case of wettable powders, solutions and emulsions.
It can be included in a concentration of % by weight. Furthermore, the herbicide of the present invention can contain fungicides, insecticides, nematicides, fertilizers, plant growth regulators, etc. commonly used in the agricultural field, and can also be used in combination with other herbicides. can. In addition, among the 2,3-dicyanopyrazine derivatives provided by the present invention, the 2,3-dicyano-5-alkylaminopyrazine derivative represented by formula (-3) is particularly suitable for germination when applied to paddy fields or upland fields. It has the effect of selectively whitening and killing weeds (chlorosis). Next, the method for producing the compound of the present invention will be specifically explained with reference to Examples. Example 1 2,3-dicyano-5-hydroxy-6-
Synthesis of (3,4-dichlorophenyl)pyrazine 7.56 g of diaminomaleonitrile and 15.4 g of 3,4-dichlorophenylglyoxylic acid were mixed in methanol.
After dissolving in 100ml and adding 36ml of 4N hydrochloric acid,
The mixture was warmed to ℃ and stirred for 2 hours. The reaction solution was cooled to 5° C., and the precipitated crystals were separated and recrystallized from ethanol to obtain 16.7 g of 2,3-dicyano-5-hydroxy-6-(3,4-dichlorophenyl)pyrazine. Melting point 228-230℃ (decomposition) Elemental analysis value C ₁₂ H ₄ N ₄ OCl ₂ Calculated value C49.51 H1.39 N19.25 Actual value C49.50 H1.44 N19.01 Example 2 2.3-dicyano -Synthesis of 5-chloro-6-furylpyrazine 21.2 g of 2,3-dicyano-5-hydroxy-6-furylpyrazine synthesized in the same manner as in Example 1
was dissolved in 150 g of phosphorus oxychloride, and 7.9 g of pyridine was added dropwise over about 20 minutes under ice cooling. Then 100℃
After stirring for 3.0 hours, excess phosphorus oxychloride was removed under reduced pressure and the residue was dissolved in 350 ml of toluene. After washing the toluene solution three times with 150 ml of water, the solid obtained by distilling off the toluene was recrystallized from ethanol to obtain 17.2 g of 2,3-dicyano-5-chloro-6-furylpyrazine. Melting point 118-119.5℃ Elemental analysis value C ₁₀ H ₃ N ₄ Calculated value as OCl C52.08 H1.31 N24.30 Actual value C52.31 H1.30 N24.56 Example 3 2,3-dicyano-5-n -Propylamino-
Synthesis of 6-(3-methoxyphenyl)pyrazine 2,3-dicyano-5-chloro-6-(3-methoxyphenyl) synthesized in the same manner as in Example 2
2.70 g of pyrazine was dissolved in 50 ml of acetone, cooled to 5°C, and 1.18 g of n-propylamine was added.
Stir for 15 minutes at ~10°C. After the reaction, the solvent was distilled off, 60 ml of water was added to the residue, the precipitated solid was separated, and recrystallized from ethanol to give 1.70 g of 2.3
-dicyano-5-n-propylamino-6-(3
-methoxyphenyl)pyrazine was obtained. Melting point 121-122℃ Elemental analysis value Calculated value as C ₁₆ H ₁₅ N ₅ O C65.51 H5.15 N23.88 Actual value C65.46 H5.10 N23.90 Examples 4-20 Examples 1, 2 and 3 Compounds shown in Table 1 below were synthesized by a method similar to .

【table】

【table】

[Table] Next, specific examples of herbicide formulations provided by the present invention will be further explained using the following formulation examples. In the formulation examples, "parts" are parts by weight. Formulation Example 1 (Wettable powder) 10 parts of the active compound of the present invention, 87.3 parts of talc as a carrier material, 1.35 parts of Neopellex [trade name: manufactured by Kao Atlas Co., Ltd.] as a surfactant, and Solpol 800A [trade name: Toho Mix and grind with 1.35 parts of Kagaku Kogyo Co., Ltd. to obtain a 10% hydrating powder. Formulation example 2 (emulsion) 15 parts of active compound of the invention, tetrahydrofuran
Mix and dissolve 80 parts and 5 parts of a surfactant (Solpol 800A) to obtain a 15% emulsion. Formulation example 3 (granules) 10 parts of the active compound of the present invention, 50 parts of bentonite,
35 parts of Kunilite and surfactant (Solpol)
After mixing and pulverizing 5 parts of 800A), add 10 parts of water, stir evenly, extrude through a sieve hole with a diameter of 0.7 mm, dry and cut into appropriate lengths to obtain 10% granules. Next, the results of plant tests of the herbicide according to the present invention will be shown, and the method of use of the herbicide and its effects will be clarified. Note that the numbers of active compounds correspond to the numbers of the above examples. Test Example 1 (Paddy field flooded soil treatment method) A 1/5000 are polyethylene pot was filled with paddy soil (planted soil), seeds of wild grass, broad-leaved weeds, and scallops were sown in a 2 cm layer on the surface.
I transplanted the sheet. At the same time, two 3-leaf stage paddy rice plants were planted, transplanted to a depth of 2 cm, and flooded to a depth of 3 cm. At the same time as weed germination, a predetermined amount of a wettable powder containing the active compound of the present invention was weighed out, diluted to 10 ml of water per pot, and dropped onto the water surface. Thereafter, the plants were grown in a glass room, and three weeks after the treatment, the herbicidal effect and the effect on paddy rice were investigated. The results are shown in Table 2 below. In addition, the numerical values in the table in the following test examples indicate the degree of crop damage and herbicidal effect, and are specifically as follows.

【table】

【table】

【table】

Claims (1)

[Claims] 1. General formula [In the formula, A represents a thienyl group, a furyl group, or a group of the formula [Formula], and B represents a chlorine atom, a hydroxyl group, or a lower alkylamino group: Here, R ₁ represents a hydrogen atom or a lower alkoxy group, R ₂ represents a nitro group, a trifluoromethyl group, a carbamoyl group, a cyano group or a lower alkoxy group, or R ₁ and R ₂ simultaneously represent a halogen atom. ] A 2,3-dicyanopyrazine derivative represented by the following. 2 Diaminomaleonitrile is represented by the general formula A-COCOOH () [wherein A represents a thienyl group, a furyl group, or a group of the formula [formula]: Here, R ₁ represents a hydrogen atom or a lower alkoxy group, and R ₂ represents a It represents a nitro group, a trifluoromethyl group, a carbamoyl group, a cyano group or a lower alkoxy group, or R ₁ and R ₂ simultaneously represent a halogen atom. ] A general formula characterized by reacting with an α-ketocarboxylic acid represented by [In the formula, A has the above meaning. ] A method for producing a 2,3-dicyano-5-hydroxypyrazine derivative. 3 General formula [In the formula, _A represents a thienyl group, a furyl group, _or a group of the formula or a lower alkoxy group, or R ₁ and R ₂ simultaneously represent a halogen atom. ] A general formula characterized by halogenating a 2,3-dicyano-5-hydroxypyrazine derivative represented by [In the formula, A has the above meaning, and X represents a halogen atom. ] A method for producing a 2,3-dicyano-5-halopyrazine derivative. 4 General formula [In the formula, A represents a thienyl _group , a furyl group _, or a group of the formula represents a fluoromethyl group, a carbamoyl group, a cyano group or a lower alkoxy group, or R ₁ and R ₂
and simultaneously represent a halogen atom. ] A general formula characterized by reacting a 2,3-dicyano-5-halopyrazine derivative represented by with a lower alkylamine [In the formula, A has the above meaning, and R ₃ represents a lower alkyl group. ] A method for producing a 2,3-dicyano-5-alkylaminopyrazine derivative. 5 General formula [In the formula, A represents a thienyl group, a furyl group, or a group of the formula [formula], and B represents a chlorine atom, a hydroxyl group, or a lower alkylamino group: Here, R ₁ represents a hydrogen atom, and R ₂ represents a nitro group. , a trifluoromethyl group, a cyano group or a lower alkoxy group, or R ₁ and R ₂ simultaneously represent a halogen atom. ] A herbicide containing a 2,3-dicyanopyrazine derivative as an active ingredient.