CH650253A5 - PYRIDINE AND PYRAZINE DERIVATIVES AND THEIR USE AS FUNGICIDAL ACTIVE SUBSTANCES. - Google Patents

Description

The invention relates to compounds of the general formula 60

R3

wherein - I

R12-halogen, 4-halogen or 2,4-dihalophenyl, R'-C-CH-R2

R2 3-pyridyl-l-oxide, 2-pyrazinyl-l-oxide, 2-pyrazinyl-4-oxide 65 ||

or 2-pyrazinyl-1,4-dioxide, N

R3 is hydrogen or straight-chain Ci-4-alkyl and |

R4 Ci-6-alkyl, C3-6-cycloalkyl, C3 - <> - alkenyl or C3-6-OR4

3rd

650253

wherein

R12-halogen, 4-halogen or 2,4-dihalophenyl, R2 3-pyridyl-l-oxide, 2-pyrazinyl-l-oxide, 2-pyrazinyl-4-oxide or 2-pyrazinyl-1,4 -dioxide,

R3 is hydrogen or straight-chain Ci-4-alkyl and R4 Ci-6-alkyl, C3-6-cycloalkyl, C3-6-alkenyl or C3-6-alkynyl, and acid addition salts of these compounds.

The compounds of formula I and their acid addition salts have fungicidal properties and are suitable as fungicidal active ingredients, in particular for use in agriculture and horticulture.

The invention further relates to a process for the preparation of the compounds of the formula I and their acid addition salts, compounds of the formula I and acid addition salts thereof as fungicidal active substances, fungicidal agents which contain compounds of the formula I or acid addition salts thereof as active substances, and a process for combating fungi in agriculture and horticulture using such compounds or acid addition salts.

The term "halogen" in the definition of formula I includes fluorine, chlorine, bromine and iodine, with chlorine being preferred.

The halogen atoms in the radical R1 in the meaning 2,4-dihalophenyl can be the same or different.

The terms "Ci-e-alkyl", "C3-6-alkenyl" and "C3-6-alkynyl" encompass both straight-chain and branched hydrocarbon radicals. Depending on the number of carbon atoms, alkyl is e.g. to understand the following groups: methyl, ethyl, n-propy, isopropyl, n-butyl, tert. Butyl, isoamyl and n-hexyl.

R4 with the meaning Ci-6-alkyl, C3-6-alkenyl or C3-6-alkynyl is preferably Ci-4-alkyl, C3- or Ct-alkenyl or G- or C4-alkynyl. A particularly preferred alkenyl or alkynyl group is the allyl or propargyl group.

R 'is preferably 4-chlorophenyl or 2,4-dichlorophenyl, especially the latter group.

R 'is preferably hydrogen, methyl or ethyl, especially hydrogen.

A particularly preferred compound of formula I is the 2 ', 4'-dichloro-2- (3 "-pyridyl) -acetophenone-0-methyl-oxime-1" oxide.

Other representatives of compounds of the formula I are:

2 ', 4' -dichloro-2- (3 "-pyridyl) -acetophenone-0-ethyloxime-1" oxide,

2 ', 4' -dichloro-2- (3 "-pyrazinyl) -acetophenone-0-methyloxime-1" oxide,

2 ', 4' -dichloro-2- (3 "-pyrazinyl) -acetophenone-0-methyloxime-4" oxide,

2 ', 4' -Dichlor-2- (3 "-pyrazinyl) -acetophenone-0-ethyloxime-1" -oxide and 2 ', 4'-dichloro-2- (3 "-pyrazinyl) -acetophenone-0-ethyl -oxime-4 "oxide.

The presence of the C = N double bond in the compounds of the formula I gives rise to geometric isomerism (E and Z isomers). In addition, asymmetric carbon atoms can be present, so that the compounds can exist as optical antipodes. Formula I is therefore intended to encompass all of these possible isomeric forms.

Suitable acid addition salts of the compounds of the formula I are physiologically tolerable salts with strong acids. These preferably include salts of the compounds I with inorganic acids, such as hydrochloric acid, nitric acid and phosphoric acid, and with sulfonic acids, such as 1,5-naphthalene disulfonic acid.

The process according to the invention for the preparation of the compounds of the formula I and of their salts is characterized in that a) a pyridine or pyrazine derivative of the general formula

R3

R'-C-CH-R2 'II

II

N

I.

OR4

wherein R1, R3 and R4 have the meanings given above and R2 'is 3-pyridyl or 2-pyrazinyl, N-oxy-dated, or b) a ketone of the general formula

R3

R'-C-CH-R2 111

II

O

wherein R1, R2 and R3 have the meanings given above, with an O-substituted hydroxylamine of the general formula

R4iONH2 IV

wherein R41 means C1-6-alkyl, C3-6-cycloalkyl or C3-6-alkenyl, and, if desired, convert a compound of general formula I obtained into an acid addition salt.

Process variant a) can expediently be carried out by oxidizing the starting material of the formula II using hydrogen peroxide or a peracid in the presence of an inert diluent.

If hydrogen peroxide is used as the oxidizing agent, lower alkanols such as methanol, ethanol and isopropanol are particularly suitable as diluents, and the oxidation is preferably in a temperature range between 0 ° and 60 ° C., in particular between 20 ° and 40 ° C, made.

Peracetic acid, per-benzoic acid and m-chloroperbenzoic acid are preferred as peracids, preferably in a halogenated hydrocarbon, e.g. Methylene chloride or chloroform, as a diluent. The oxidation with a peracid is preferably carried out in a temperature range between 0 ° C. and the reflux temperature of the reaction mixture, in particular between 0 ° C. and room temperature. A particularly preferred embodiment of this process consists in carrying out the oxidation with m-chloroperbenzoic acid in chloroform in a temperature range between 0 ° C. and room temperature.

According to process variant b), which leads to compounds of the formula I in which R4 is C1-6-alkyl, C3-6-cycloalkyl or C3-6-alkenyl, the reaction is conveniently carried out in an organic solvent, e.g. an alcohol, such as methanol or ethanol, a dialkylamide, such as dimethylformamide, or a tertiary amine, such as pyridine. One works preferably in a Temperaturbes

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range between the room temperature and the reflux temperature of the reaction mixture. Since the starting material of formula IV is preferably in the form of an acid addition salt, e.g. of the hydrochloride or hydrosulfate is used, a base such as sodium or potassium carbonate, triethylamine or pyridine is advantageously added to the reaction mixture.

For the preparation of acid addition salts, the compounds of formula I with the desired acids, such as e.g. Hydrochloric acid, nitric acid, phosphoric acid, or a sulfonic acid.

The compounds of the formula I and their acid addition salts thus prepared are isolated and purified by methods known per se.

The starting materials of formula II can be prepared by using an oxime of the general formula

R3

I.

R'-C-CH-R2 'V

II

N OH

wherein R1, R2 'and R3 have the meanings given above, with a compound of the general formula

R4U VI

wherein

R4 has the meaning given above and U is a leaving group, e.g. Chlorine, bromine, iodine, mesyloxy, tosyloxy or an alkyl sulfate residue, means, or a ketone of the general formula

R3

I.

R'-C-CH-R2 'VII

II

O

wherein R1, R2 'and R3 have the meanings given above, with an O-substituted hydroxylamine of the general formula

R41ONH2 IV

where R41 is Ci-6-alkyl, C3-6-cycloakyl or C3-6-alkenyl.

The reaction of the oxime of the formula V with the compound of the formula VI can be carried out by the oxime V with the compound VI, advantageously in the presence of a base, in an organic solvent and in a temperature range between 0 ° C. and the reflux temperature of the reaction mixture transferred. The solvent can be protic or non-protic. In the case of protic solvents such as alcohols, especially methanol or ethanol, the base used is preferably an alkali metal hydroxide, e.g. Sodium or potassium hydroxide, or an alkali metal alcoholate. When using non-protic solvents, such as aliphatic or alicyclic ethers, especially tetrahydrofuran or dimethoxyethane, and dialkylamides, especially dimethylformamide, the base is preferably an alkali metal hydride, e.g. Sodium hydride. In a preferred embodiment of this method, sodium hydride as the base and an aliphatic or alicyclic ether, in particular tetrahydrofuran or dimethoxyethane, or a

Dialkylamide, especially dimethylformamide, used as a solvent.

The reaction of the ketone of the formula VII with the hydroxylamine of the formula IV, which leads to compounds of the formula II in which R4 is C1-6-alkyl, C3-6-cycloalkyl or C3-6-alkenyl, is advantageously carried out analogously to that described above Process variant b).

The starting materials of the formula III can be prepared by N-oxidizing the above-mentioned ketone of the general formula VII analogously to process variant a) described above.

The compounds of the formulas IV, V, VI and VII which can be used as starting materials are either known or can be prepared by methods known per se. For example, the oximes of formula V can be obtained from the corresponding ketones of formula VII by reaction with hydroxylamine, and the ketones themselves according to the methods described in DOS 2 221546, DOS 2 800 010 and British Patent No. 2015 524, i.e. e.g. by condensation of the corresponding methylated heterocycle with a halogenated alkyl benzoate.

The compounds according to the invention, i.e. the compounds of formula I and their acid addition salts have fungicidal activity and can accordingly be used to combat fungi in agriculture and horticulture. They are particularly suitable for curbing growth or for destroying phytopathogenic fungi on parts of plants, e.g. Leaves, stems, roots, tubers, fruits or flowers, and on seeds and in the soil and are particularly effective in combating botrytis cinerea (gray rot); powdery mildew fungi such as Uncinula necator (grape mildew), Erysiphe cichoracearum (cucumber mildew), Podosphaera leucotricha (apple mildew) and Erysiphe gra-minis (barley mildew); from Venturia inaequalis (apple scab); of Helminthosporium oryzae (brown spot disease of rice); and harmful fungi of the genera Puccinia, Uromyces, Rhizoctonia, Pénicillium, Septoria and Cerco-spora.

Individual representatives of the compounds according to the invention also have a pronounced action against wood-destroying fungi, such as Coniophora puteana and Gloeophyllum trabeum.

The compounds according to the invention are notable for local and / or systemic action.

The compounds according to the invention act under greenhouse conditions even at a concentration of 10 mg to 500 mg of active substance per liter of spray mixture. In the field, concentrations of 50 g to 2000 g of active ingredient of the formula I per hectare and treatment are advantageously used.

Using formulation auxiliaries, the compounds according to the invention, that is to say the fungicidal active ingredients, can be converted into the customary formulations, such as dusts, powders, granules, solutions, emulsions, suspensions, emulsifiable concentrates, pastes and the like. The fungicidal composition according to the invention is characterized in that it contains an effective amount of at least one compound of the general formula I, as defined above, or an acid addition salt of such a compound and formulation auxiliaries. The compositions expediently contain at least one of the following formulation auxiliaries:

Solid carriers; Solvents or dispersants; Ten-side (wetting and emulsifying agents); Dispersants (without surfactant); and stabilizers.

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The following are essentially suitable as solid carriers: natural minerals, such as kaolin, clays, kieselguhr, talc, bentonite, chalk, e.g. Sludge chalk, magnesium carbonate, limestone, quartz, dolomite, attapulgite, montmo rillonite and diatomaceous earth; synthetic minerals such as finely divided silica, aluminum oxide and silicates; organic substances such as cellulose, starch, urea and synthetic resins; and fertilizers such as phosphates and nitrates, such carriers e.g. can be present as granules or powder.

The following are essentially suitable as solvents or dispersing agents: aromatics, such as benzene, toluene, xylenes and alkylnaphthalenes; chlorinated aromatics and chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chloroethylene and methylene chloride; aliphatic hydrocarbons such as cyclohexane and paraffins, e.g. Petroleum fractions; Alcohols, such as butanol and glycol, and their ethers and esters; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; and strongly polar solvents or dispersing agents, such as dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide, such solvents or dispersing agents preferably having flash points of at least 30 ° C. and boiling points of at least 50 ° C., and water. So-called liquefied gaseous extenders or carriers, which are products which are gaseous at room temperature and under normal pressure, are also suitable among the solvents or dispersants. Examples of such products are in particular aerosol propellants such as halogenated hydrocarbons, e.g. Dichlorodifluoromethane. In the case of using water as a solvent, e.g. organic solvents can also be used as auxiliary solvents.

The surfactants (wetting and emulsifying agents) can be nonionic compounds, such as condensation products of fatty acids, fatty alcohols or fat-substituted phenols with ethylene oxide; Fatty acid esters and ethers of sugars or polyhydric alcohols; the products obtained from sugars or polyhydric alcohols by condensation with ethylene oxide; Block polymers of ethylene oxide and propylene oxide; or alkyldimethylamine oxides.

The surfactants can also be anionic compounds, such as soaps; Fatty sulfate esters, e.g. Dodecyl sodium sulfate, octadecyl sodium sulfate and cetyl sodium sulfate; Alkyl sulfonates, aryl sulfonates and fatty aromatic sulfonates such as alkyl benzene sulfonates, e.g. Calcium dodecylbenzene sulfonate and butylnaphthalene sulfonates; and more complex fatty sulfonates, e.g. the amide condensation products of oleic acid and N-methyl taurine and the sodium sulfonate of dioctyl succinate.

Finally, the surfactants can be cationic compounds, such as alkyldimethylbenzylammonium chlorides, dialkyldimethylammonium chlorides, alkyltrimethylammonium chlorides and ethoxylated quaternary ammonium chlorides.

The following are essentially suitable as dispersants (without surfactant action): lignin, sodium and ammonium salts of lignin sulfonic acid, sodium salts of maleic anhydride-diisobutylene copolymers, sodium and ammonium salts of sulfonated polycondensation products of naphthalene and formaldehyde, and sulfite waste liquors.

As dispersants, which are particularly suitable as thickeners or. Anti-settling agents are suitable, e.g. Methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, alginates, caseinates and blood albumin can be used.

Examples of suitable stabilizers are acid-binding agents, e.g. Epichlorohydrin, phenylglycidyl ether and soya epoxides, antioxidants e.g. Gallic acid esters and

Butylated hydroxytoluene; UV absorbers e.g. substituted benzophenones, diphenylacrylonitrile acid esters and cimic acid esters; and deactivators e.g. Salts of ethylenediaminetetraacetic acid and polyglycols.

In addition to the active compounds of the formula I, the fungicidal compositions according to the invention can also contain other active compounds, e.g. other fungicides, insecticides and acaricides, bactericides, plant growth regulators and fertilizers. Such combination agents are suitable for broadening the spectrum of activity or for specifically influencing plant growth.

In general, the fungicidal compositions according to the invention, depending on the type, contain between 0.0001 and 95 percent by weight of the compound or compounds according to the invention as active ingredient (s). They can be in a form suitable for storage and transportation. In such forms, e.g. emulsifiable concentrates, the active ingredient concentration is normally in the higher range of the above concentration series. These forms can then be diluted with the same or different formulation adjuvants to active ingredient concentrations that are suitable for practical use, and such concentrations are normally in the lower range of the concentration series above. Emulsifiable concentrates generally contain 5 to 95 percent by weight, preferably 25 to 75 percent by weight, of the compound or compounds of the formula I. ready-to-use solutions, emulsions and suspensions, which are suitable, for example, as spray liquors. In such spray liquors e.g. Concentrations between 0.0001 and 20 percent by weight are present. In the ultra-low-volume process, spray liquors can be formulated in which the active compound concentration is preferably from 0.5 to 20 percent by weight, while the spray liquors formulated in the low-volume process and in the high-volume process preferably have an active compound concentration of 0. 02 to 1.0 or 0.002 to 0.1 percent by weight.

The fungicidal compositions according to the invention can be prepared by mixing at least one compound of the general formula I or an acid addition salt of such a compound with formulation auxiliaries.

The preparation of the agents can be carried out in a known manner, e.g. by mixing the active ingredient with solid carriers, by dissolving or suspending in suitable solvents or dispersing agents, possibly using surfactants as wetting or emulsifying agents or dispersing agents, by diluting previously prepared emulsifiable concentrates with solvents or dispersing agents, etc.

In the case of powdered agents, the active ingredient can be mixed with a solid carrier, e.g. by grinding together; or you can impregnate the solid carrier with a solution or suspension of the active ingredient and then remove the solvent or dispersion medium by evaporation, heating or by suction under reduced pressure. By adding surfactants or dispersants, such powdery compositions can be made easily wettable with water, so that they can be dissolved in aqueous suspensions, e.g. suitable as a spray, can be transferred.

The compounds according to the invention can also be mixed with a surfactant and a solid carrier to form a wettable powder which is dispersible in water, or they can be mixed with a solid pregranulated carrier to form a granular product.

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6

If desired, a compound according to the invention can be dissolved in a water-immiscible solvent, such as, for example, an alicyclic ketone, which advantageously contains dissolved emulsifiers, so that the solution has a self-emulsifying effect when added to water. Otherwise, the active ingredient can be mixed with an emulsifier and the mixture can then be diluted with water to the desired concentration. In addition, the active ingredient can be dissolved in a solvent and then mixed with an emulsifier. Such a mixture can also be diluted with water to the desired concentration. In this way, emulsifiable concentrates or ready-to-use emulsions are obtained.

The agents according to the invention can be used according to the application methods customary in crop protection or in agriculture, such as spraying, spraying, dusting, pouring or scattering. The method according to the invention for combating fungi is characterized in that the goods to be protected, e.g. Plants, parts of plants or seeds, treated with an effective amount of a compound according to the invention.

The following examples illustrate the invention.

Production of active ingredients of formula I:

example 1

A solution of 10 g of 2 ', 4'-dichloro-2- (3-pyridyl) aceto-phenon-O-methyloxime in 100 ml of chloroform is mixed with 7.2 g of m-chloroperbenzoic acid at 0 ° C. and then for 24 hours stored in the refrigerator at approx. 4 ° C. Then it is diluted with 200 ml of chloroform and extracted with 250 ml of 10% potassium carbonate solution. The organic phase is dried over anhydrous sodium sulfate and concentrated. The residue obtained is 2 ', 4' -dichloro-2- (3 "-pyridyl) -acetophenone-0-methyloxime-1" -oxide as E, Z isomer mixture in the form of a yellowish paste.

Example 2

I, 41 g of 2 ', 4' -dichloro-2- (3 "-pyridyl) -acetophenone-1" oxide are dissolved in 5 ml of ethanol, mixed with 1 g of sodium carbonate and 0.83 g of O-methylhydroxylamine hydrochloride and then heated under reflux for 3 hours. Then it is poured onto ice and extracted with ethyl acetate, and the organic phase is dried over anhydrous sodium sulfate and then concentrated. The residue consists of 2 ', 4'-dichloro-2- (3 "-pyridyl) -aceto-phenon-O-methyloxime-1" oxide.

II. Production of the starting materials:

Example 3

A solution of 13.3 g2 ', 4'-dichloro-2- (3-pyridyl) aceto-phenone in 40 ml of ethanol is mixed with 10 g of sodium carbonate and 8.3 g of O-methylhydroxylamine hydrochloride and then stirred on Reflux temperature heated. After 4 hours the reaction mixture is poured onto ice and extracted with ethyl acetate. The organic phase is washed, dried over anhydrous sodium sulfate and concentrated under reduced pressure. This gives 2 ', 4'-dichloro-2- (3-pyridyl) acetophenone-0-methyloxime as an E, Z isomer mixture in the form of a yellowish oil.

Example 4

A solution of 5 g of 2 ', 4' -dichloro-2- (3-pyridyl) aceto-phenone in 20 ml of chloroform is mixed with 3.6 g of m-chloroperbenzoic acid at 0 ° C and then in the refrigerator for 24 hours at approx 4 ° C. Then it is diluted with 100 ml of chloroform and extracted with 100 ml of 10% potassium carbonate solution. The organic phase is dried over anhydrous sodium sulfate and concentrated. This gives 2 ', 4'-dichloro-2- (3 "-pyridyl) -acetophenone-1" oxide, mp. 137-140 ° C.

Example 5

A mixture of 27.6 g of 2,4-dichlorobenzoic acid ethyl ester and 20.81 g of 3-pyridylacetic acid ethyl ester at 20-25 ° C. is mixed in portions with 10.59 g of sodium methylate. The reaction mixture is then heated to 65-70 ° C, and volatile products are blown off with dry nitrogen. After 20 hours, 40 ml of concentrated hydrochloric acid are added and the mixture is heated at the reflux temperature for 18 hours. The mixture is washed with diethyl ether and the aqueous phase is made basic by adding concentrated ammonia and extracted with methylene chloride. The organic phase is concentrated and the crude product is chromatographed on silica gel with methylene chloride / methanol (98: 2). The product, 2 ', 4'-dichloro-2- (3-pyridyl) acetophenone, can be crystallized from diethyl ether / n-pentane and melts at 55-56 ° C.

III. Formulation examples

Example 6

1. wettable powder (for active ingredients that melt or melt below 75 ° C)

Parts by weight

Active ingredient of formula I.

50

Hydrated silica

37

kaolin

5

Alkylphenol ethoxylate

4th

Sodium polynaphthalene sulfonate

4th

100

The liquid or melted active ingredient is drawn onto the silica, the other components are mixed in and the whole is finely ground in a suitable mill.

2. Spray powder (for solid active ingredients melting above 75 ° C)

Parts by weight

Active ingredient of formula I.

50

Hydrated silica

5

kaolin

42

Sodium lauryl sulfate

1

Sodium lignosulfonate

2nd

100

The components are mixed together and the whole is finely ground in a suitable mill.

Example 7

Emulsifiable concentrate (for active ingredients that are liquid at 20-25 ° C)

Parts by weight

Active ingredient of formula I 500

Castor oil ethoxylate 100

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Calcium dodecylbenzenesulfonate

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Vol. Parts

The components are mixed together until a clear solution is obtained.

Claims (10)

650253 2. Compounds according to claim 1, wherein R14 is chlorophenyl or 2,4-dichlorophenyl. 2nd PATENT CLAIMS 1. Compounds of the general formula R3 | s R'-C-CH-R2 I II N I. OR "io Mean alkynyl, and of their acid addition salts, characterized in that a pyridine or pyrazine derivative of the general formula R3 I. R'-C-CH-R2 ' II N I. OR4 II wherein R12-halogen, 4-halogen or 2,4-dihalophenyl, R2 3-pyridyl-l-oxide, 2-pyrazinyl-l-oxide, 2-pyrazinyl-4-oxide or 2-pyrazinyl-1,4 -dioxide, R3 represents hydrogen or straight-chain Ci-4-alkyl and R4 Ci-6-alkyl, C3-6-cycloalkyl, C3-6-alkenyl or C3-6-alkynyl, and acid addition salts of these compounds. 3. Compounds according to claim 1 or 2, wherein R3 is hydrogen. 4. 2 ', 4'-dichloro-2- (3 "-pyridyl) -acetophenone-0-methyl-oxime-1" oxide, as a compound according to claim 1. 5. A compound or an acid addition salt according to any one of claims 1 to 4 as a fungicidal active ingredient. 6. Fungicidal agent, characterized in that it is an effective amount of at least one compound of the general formula R3 I. R'-C-CH-R2 I II N I. OR4 wherein R ', R3 and R4 have the meanings given above and R2' is 3-pyridyl or 2-pyrazinyl, N-oxy-ls dated and, if desired, converting a compound of general formula I obtained into an acid addition salt. 7. Fungicidal composition according to claim 6, characterized in that it contains an effective amount of 2 ', 4' -dichloro-2- (3 "-pyridyl) -acetophenone-0-methyloxime-1" oxide and formulation auxiliaries. 8. Process for the preparation of compounds of the general formula R3 I. R'-C-CH-R2 I wherein R1, R2 and R3 have the meanings given above, with an O-substituted hydroxylamine of the general formula IV wherein R41 has the meaning given above, converts, 50 and, if desired, converts a compound of general formula I obtained into an acid addition salt. 9. Process for the preparation of compounds of the general formula 20 R3 I. R'-C-CH-R2 I ' II N I. OR41 25th wherein R '2-halo, 4-halo or 2,4-dihalophenyl, 30 R2 3-pyridyl-l-oxide, 2-pyrazinyl-1-oxide, 2-pyrazinyl-4-oxide or 2-pyrazinyl- 1,4-dioxide, R3 is hydrogen or straight-chain Ci-4-alkyl and R41 Ci-6-alkyl, C3-6-cycloalkyl or C3-6-alkenyl, and of their acid addition salts, characterized in that a ketone of the general formula is used R3 I. R'-C-CH-R2 II O III where 40 R12-halogen, 4-halogen or 2,4-dihalophenyl, R2 3-pyridyl-1-oxide, 2-pyrazinyl-1-oxide, 2-pyrazinyl-4-oxide or 2-pyrazinyl-1, 4 -dioxide, R3 is hydrogen or straight-chain Ci-4-alkyl and R4 Ci-6-alkyl, C3-6-cycloalkyl, C3-6-alkenyl or C3-6-alkynyl, or an acid addition salt of such a compound and formulation auxiliaries. R41ONH2 10. A method for combating fungi in agriculture and horticulture, characterized in that the material to be protected is treated with an effective amount of at least 55 min one of the compounds mentioned in claims 1 to 4. N I. OR4