JP7437783B2 - Rice blast control agent - Google Patents

Description

The present invention relates to an agent for controlling rice blast disease and a method for controlling rice blast disease.

Rice blast is an important disease of water rice. The rice blast fungus synthesizes melanin to strengthen its own cell wall and invades rice plants, but if melanin synthesis is inhibited, the strength of the cell wall decreases and it is unable to invade. For this reason, pesticides for rice blast fungi currently on the market focus on the melanin production pathway within the fungus (see Figure 1), and target specific enzymes involved in each step leading to melanin production. It was developed. For example, Bayer introduced carpropamide in 1998, Sumitomo Chemical introduced diclosimet in 2000, and Nihon Nohyaku introduced phenoxanil in 2001 as pesticides that target citalone dehydratase (SDH1), which is involved in one step of the pathway. There was a time when these drugs were put on the market and used widely, but in 2001, resistant bacteria appeared and the desired effects could no longer be obtained, so they are no longer used.

Until now, patent applications have been filed for rice blast control agents containing various compounds as active ingredients (for example, Patent Documents 1 to 4), but it has been reported that compounds having a coumarin skeleton are effective as rice blast control agents. There are no reports.

Regarding N-substituted-4-(3-amino-2-benzofuranyl)coumarin derivatives, for example, N-(2-furanylcarbonyl) derivatives are described in Non-Patent Document 1; is not mentioned at all.

Japanese Unexamined Patent Publication No. 15867/1986 Japanese Patent Application Publication No. 8-295661 Japanese Unexamined Patent Publication No. 132867/1986 International Publication No. 99/11127

Frasinyuk, M. S., et al., Chemistry of Heterocyclic Compounds (New York, NY, United States) (2009), 45(10), 1261-1269.

An object of the present invention is to provide a novel citalone dehydratase inhibitor, a novel rice blast control agent, and a novel compound useful as an active ingredient thereof.

The present inventors conducted various studies to solve the above problems, and found that coumarin derivatives with a predetermined structure also inhibit citalone dehydratase (SDH1) and/or its amino acid mutants, which are involved in the melanin production pathway. It was found that it has activity. Based on this knowledge, we further conducted various studies and found that by applying the coumarin derivatives, melanin production can be significantly suppressed and controlled against wild-type rice blast fungi and/or their drug-resistant bacteria. They discovered this and completed the present invention.

（式中、Ａ^１～Ａ^４はそれぞれ、ＣＨ又はＮを表し；Ｒは水素原子以外の置換基であり、ｎは０～４の整数であり、ｎが２以上のとき複数のＲは互いに同一であっても異なっていてもよく、隣り合う炭素原子に結合したＲは互いに結合して環を形成していてもよく；Ｘ^１及びＸ^２はそれぞれ、水素原子、Ｃ_１－１０－アルキル基、－ＣＯ－Ｒ^５、－ＣＯ－ＯＲ^５又は－ＳＯ_２－Ｒ^５であり；Ｒ^５は置換又は非置換の炭素数１～１０の炭化水素基、又は置換又は非置換のヘテロ環基である。）
で示される化合物から選ばれる少なくとも１種を含有するシタロン脱水酵素阻害剤。
（２）前記式（Ｉ）中、Ｒが表す前記置換基が、置換又は非置換のＣ_１－１０－アルキル基、置換又は非置換のＣ_１－１０－アルコキシ基、置換又は非置換のＣ_６－１０－アリールオキシ基、置換又は非置換のＣ_７－１１－アラルキルオキシ基、ハロゲン原子、又は水酸基である前記（１）に記載のシタロン脱水酵素阻害剤。
（３）前記式（Ｉ）が次式（II）：

（式中、Ｒ^１及びＲ^２のいずれか一方は、置換又は非置換のＣ_１－５－アルキル基、又は置換又は非置換のＣ_１－５－アルコキシ基であり、Ｒ^１及びＲ^２の他方は、水素原子、置換又は非置換のＣ_１－５－アルキル基、又は置換又は非置換のＣ_１－５－アルコキシ基であり；Ｒ^３及びＲ^４は、それぞれ、水素原子、水酸基、ベンジルオキシ基、Ｃ_２－６－アルカノイルオキシ基、置換又は非置換のＣ_１－５－アルキル基、又は置換又は非置換のＣ_１－５－アルコキシ基であり；Ｘ^２は前記式（Ｉ）中のＸ^２と同義である。）
である前記（１）又は（２）に記載のシタロン脱水酵素阻害剤。
（４）前記式（II）中の置換又は非置換のＣ_１－５－アルコキシ基がメトキシメトキシ基、（２－メトキシエトキシ）メトキシ基、［２－（トリメチルシリル）エトキシ］メトキシ基又はベンジルオキシメトキシ基である前記（３）に記載のシタロン脱水酵素阻害剤。
（５）少なくとも１種のアミノ酸が変異した非野生型シタロン脱水酵素に対して阻害活性を有する前記（１）～（４）のいずれかに記載のシタロン脱水酵素阻害剤。
（６）前記（１）～（５）のいずれかに記載のシタロン脱水酵素阻害剤を含有するイネいもち病防除剤。
（７）イネいもち病菌のメラニン生合成経路に関与する、ポリケタイド合成酵素及び還元酵素の少なくとも１種に対して阻害活性を有する少なくとも１種の化合物を更に含有する前記（６）に記載のイネいもち病防除剤。
（８）次式（IIａ）：

（式中、Ｒ^１ａは水素原子であり、Ｒ^２ａはメチル基、又は置換又は非置換のＣ_１－３－アルコキシ基であり、Ｒ^３ａは水素原子であり、Ｒ^４ａはメチル基、水酸基、ベンジルオキシ基、Ｃ_２－６－アルカノイルオキシ基、又は置換又は非置換のＣ_１－３－アルコキシ基であり；Ｘ^ａは－ＣＯ－又は－ＳＯ_２－であり；Ｒ^５ａは置換又は非置換の炭素数１～１０の炭化水素基、又は置換又は非置換のＣ_１－３－アルコキシ基である。）
で示される化合物（但し、Ｒ^１ａ及びＲ^３ａが水素原子であり、Ｒ^２ａ及びＲ^４ａがメチル基であり、Ｘ^ａが－ＣＯ－であり、Ｒ^５ａが非置換のイソプロピル基である化合物を除く）。
（９）前記式（IIａ）中の置換又は非置換のＣ_１－３－アルコキシ基がメトキシメトキシ基、（２－メトキシエトキシ）メトキシ基、［２－（トリメチルシリル）エトキシ］メトキシ基又はベンジルオキシメトキシ基である前記（８）に記載の化合物。
（１０）前記（６）又は（７）に記載のイネいもち病防除剤を、イネの植物体自体、その種子、それが生育している又は生育が予定される圃場、又はその生育に利用される器具に施用する工程を含む、イネいもち病の防除方法。
（１１）前記（６）又は（７）に記載のイネいもち病防除剤をイネ茎葉へ散布し、又は前記イネいもち病防除剤によるイネ経根処理、田面処理、水面処理、側条処理、土壌処理、イネ種子処理又は苗箱処理に付す工程を含む前記（１０）に記載の方法。 That is, the gist of the present invention is as follows.
(1) The following formula (I):

(In the formula, A ¹ to A ⁴ each represent CH or N; R is a substituent other than a hydrogen atom, n is an integer from 0 to 4, and when n is 2 or more, multiple R They may be the same or different, and R bonded to adjacent carbon atoms may be bonded to each other to form a ring; X ¹ and X ² are each a hydrogen atom, C _1-10 -alkyl group, -CO-R ⁵ , -CO-OR ⁵ or -SO ₂ -R ⁵ ; R ⁵ is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted heterocyclic group )
A citalone dehydrase inhibitor containing at least one compound selected from the compounds shown below.
(2) In the formula (I), the substituent represented by R is a substituted or unsubstituted C _1-10 -alkyl group, a substituted or unsubstituted C _1-10 -alkoxy group, a substituted or unsubstituted C The citalone dehydrase inhibitor according to (1) above, which is a _6-10 -aryloxy group, a substituted or unsubstituted C _7-11 -aralkyloxy group, a halogen atom, or a hydroxyl group.
(3) The above formula (I) is the following formula (II):

(In the formula, either one of R ¹ and R ² is a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group, and R ¹ and R ² are The other is a hydrogen atom, a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group; R ³ and R ⁴ are a hydrogen atom, a hydroxyl group, a benzyl group, respectively; is an oxy group, ^a C _2-6 -alkanoyloxy group, a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group; ⁾
The citalone dehydrase inhibitor according to (1) or (2) above.
(4) The substituted or unsubstituted C _1-5 -alkoxy group in formula (II) is a methoxymethoxy group, (2-methoxyethoxy)methoxy group, [2-(trimethylsilyl)ethoxy]methoxy group or benzyloxymethoxy group The citalone dehydrase inhibitor according to (3) above, which is
(5) The citalone dehydrase inhibitor according to any one of (1) to (4) above, which has an inhibitory activity against a non-wild type citalone dehydratase in which at least one amino acid is mutated.
(6) A rice blast control agent containing the citalone dehydratase inhibitor according to any one of (1) to (5) above.
(7) The rice blast according to (6) above, further comprising at least one compound having an inhibitory activity against at least one of polyketide synthase and reductase, which are involved in the melanin biosynthesis pathway of the rice blast fungus. Disease control agent.
(8) The following formula (IIa):

(In the formula, R ^1a is a hydrogen atom, R ^2a is a methyl group or a substituted or unsubstituted C _1-3 -alkoxy group, R ^3a is a hydrogen atom, R ^4a is a methyl group, a hydroxyl group, is a benzyloxy group, a C _2-6 -alkanoyloxy group, or a substituted or unsubstituted C _1-3 -alkoxy group; X ^a is -CO- or -SO ₂ -; R ^5a is substituted or unsubstituted is a hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted C _1-3 -alkoxy group.)
(However, a compound in which R ^1a and R ^3a are hydrogen atoms, R ^2a and R ^4a are methyl groups, X ^a is -CO-, and R ^5a is an unsubstituted isopropyl group) except).
(9) The substituted or unsubstituted C _1-3 -alkoxy group in formula (IIa) is a methoxymethoxy group, (2-methoxyethoxy)methoxy group, [2-(trimethylsilyl)ethoxy]methoxy group or benzyloxymethoxy group The compound according to (8) above, which is a group.
(10) The rice blast control agent described in (6) or (7) above is applied to the rice plant itself, its seeds, the field where it is growing or is planned to grow, or when used for its growth. A method for controlling rice blast disease, which includes the step of applying the rice blast to a device.
(11) Spraying the rice blast control agent described in (6) or (7) above to rice stems and leaves, or treating rice with the rice blast control agent through root treatment, field surface treatment, water surface treatment, side row treatment, and soil. The method according to (10) above, including the step of subjecting the method to treatment, rice seed treatment, or seedling box treatment.

According to the present invention, it is possible to provide a novel citalone dehydratase inhibitor, a novel rice blast control agent, and a novel compound useful as an active ingredient thereof.

FIG. 1 is a schematic diagram of the melanin production pathway of the rice blast fungus. FIG. 2 shows the evaluation results of the rice blast control effect of each compound.

The present invention will be explained in detail below.
The substituent represented by R in the formula (I) is not particularly limited, and includes, for example, a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms (for example, an alkyl group, an alkenyl group, an alkynyl group, a cyclo alkyl group, cycloalkyl-alkyl group, aralkyl group), substituted or unsubstituted C _1-10 -alkoxy group, substituted or unsubstituted C _6-10 -aryloxy group, substituted or unsubstituted C _7-11 - Aralkyloxy group, substituted or unsubstituted C _1-10 -aliphatic acyl group, substituted or unsubstituted aromatic acyl group, substituted or unsubstituted C _2-10 -alkanoyloxy group, substituted or unsubstituted aromatic group Examples include an acyloxy group, an amino group, a hydroxyl group, a carboxyl group, a cyano group, a halogen atom (eg, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), and a nitro group.

In formula (I), the C _1-10 -alkyl group represented by X ¹ or X ² and the C _1-10 -alkyl group as a substituent represented by R include, for example, a methyl group and an ethyl group. , linear or branched, such as propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, etc. Examples include C _1-10 -alkyl groups.

Examples of the substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms represented by R ⁵ in the formula (I) include a C _1-10 -alkyl group, a C _2-10 -alkenyl group, a C _2- Examples thereof include _{a 10} -alkynyl group, a C _3-10 -cycloalkyl group, a C _4-10 -cycloalkyl-alkyl group, and a C _7-10 -aralkyl group.

The substituted or unsubstituted heterocyclic group represented by R ⁵ in the formula (I) is, for example, a saturated or unsaturated monocyclic ring containing 1 to 4 heteroatoms selected from O, S, and N. Examples include 3- to 8-membered, preferably 5- to 7-membered heterocyclic groups, and the heterocycles may be condensed with each other or with a cycloalkyl ring or a benzene ring to form a di- to tricyclic heterocycle. The ring atom S or N may be oxidized to form an oxide or a dioxide. The heterocycles include saturated heterocycles, aromatic heterocycles, and partially saturated heterocycles, and in the saturated heterocycles and partially saturated heterocycles, any carbon atom is substituted with an oxo group. You can. Preferably, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, imidazolyl, pyrrolyl, pyrrolidyl, triazolyl, tetrazolyl, thienyl, furyl, thiazolyl, pyrazolyl, isothiazolyl, oxazolyl, isoxazolyl, thiadiazolyl, oxadiazolyl, quinazolyl, quinoxalinyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl. , benzimidazolyl, benzothiadiazolyl, benzoxazolyl, imidazopyridyl, benzofuryl, benzothienyl, benzothiazolyl, tetrahydroquinolyl, tetrahydroisoquinolyl, piperidyl, piperazinyl, azepanyl, diazepanyl, tetrahydrofuranyl, tetrahydropyranyl, morpholinyl, indolyl , indazolyl, isoindolyl, indolinyl, tetrahydrobenzimidazolyl, dihydrobenzimidazolidinyl, chromenyl and chromanyl groups.

The above hydrocarbon groups, alkoxy groups, aryloxy groups, aralkyloxy groups, aliphatic acyl groups, aromatic acyl groups, alkanoyloxy groups and aromatic acyloxy groups include amino groups, hydroxyl groups, carboxyl groups, cyano groups, and halogen atoms. (For example, fluorine atom, chlorine atom, bromine atom, iodine atom), nitro group, etc. may be substituted with one or more substituents.

One embodiment of the formula (I) is the following formula (II).

In the formula (II), either one of R ¹ and R ² is a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group, and R ¹ and The other of R ² is a hydrogen atom, a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group; R ³ and R ⁴ are each a hydrogen atom, is a hydroxyl group, a benzyloxy group, a C _2-6 -alkanoyloxy group, a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group ^; It has the same meaning as X ² in I).

In the formula (II), the C _1-5 -alkyl group represented by R ¹ , R ² , R ³ or R ⁴ includes methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec -butyl group, tert-butyl group, pentyl group, isopentyl group, and these C _1-5 -alkyl groups include amino group, hydroxyl group, carboxyl group, cyano group, halogen atom (for example, fluorine atom, chlorine atom , bromine atom, iodine atom), nitro group, and the like.

In the formula (II), the C _1-5 -alkoxy group represented by R ¹ , R ² , R ³ or R ⁴ includes a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, Examples include sec-butoxy group, tert-butoxy group, pentyloxy group, and isopentyloxy group, and these C _1-5 -alkoxy groups include amino group, hydroxyl group, carboxyl group, cyano group, halogen atom (e.g. atom, chlorine atom, bromine atom, iodine atom), nitro group, C _1-3 -alkoxy group (e.g. methoxy group), 2-methoxyethoxy group, benzyloxy group, tri(C _1-3 -alkyl)silyl- It may be substituted with one or more substituents selected from C _1-3 -alkoxy groups (eg, 2-(trimethylsilyl)ethoxy groups) and the like.

Examples of the C _2-6 -alkanoyloxy group represented by R ³ or R ⁴ in the formula (II) include an acetoxy group.

In the substituents of -CO-R ⁵ , -CO-OR ⁵ or -SO ₂ -R ⁵ represented by X ² in the above formula (II), a hydrocarbon group having 1 to 10 carbon atoms represented by R ⁵ Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, nonyl group. , a linear or branched C _1-10 -alkyl group such as a decyl group; a C _3-10 -cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group; a vinyl group, C _2-10 -alkenyl groups such as 1-propenyl group, allyl group, 1-butenyl group, 2-butenyl group, pentenyl group, hexenyl group; ethynyl group, 1-propynyl group, 2-propynyl (propargyl) group, 3 Examples include C _2-10 -alkynyl groups such as -butynyl, pentynyl and hexynyl groups; aralkyl groups such as benzyl and phenethyl groups; and aromatic hydrocarbon groups such as phenyl, tolyl and naphthyl groups.

The hydrocarbon group is preferably a hydrocarbon group having 2 to 10 carbon atoms, and more preferably a linear or branched C _3-10 -alkyl group or C _3-10 -cycloalkyl group.

The hydrocarbon group is, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, an isopentyloxy group, a hexyloxy group, C _1-6 -alkoxy groups such as cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group; methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, butoxycarbonyl group, isobutoxy C _1-6 -alkoxy such as carbonyl group, sec-butoxycarbonyl group, tert-butoxycarbonyl group, pentyloxycarbonyl group, isopentyloxycarbonyl group, cyclopropyloxycarbonyl group, cyclobutyloxycarbonyl group, cyclopentyloxycarbonyl group - Carbonyl group; Hydroxyl group; Aromatic hydrocarbon groups such as phenyl group, tolyl group, naphthyl group; Halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom; Nitro group; C _1-6 -acyl group, carboxyl may be substituted with a group, an aralkyloxy group, a C _1-6 -alkylamino group, or a di-C _1-6 -alkylamino group.

The compound represented by the formula (II) is a compound in which R ¹ and R ² are methyl groups, and R ³ and R ⁴ are hydrogen atoms; R ² and R ⁴ are methyl groups, and R ¹ and R ³ are Compounds where R ² and R ³ are methyl groups and R ¹ and R ⁴ are hydrogen atoms; Compounds where R ¹ and R ³ are methyl groups and R ² and R ⁴ are hydrogen atoms; A compound in which R ² and R ⁴ are [2-(trimethylsilyl)ethoxy]methoxy groups, and R ¹ and R ³ are hydrogen atoms; and R ² is a methyl group, and R ⁴ is a hydroxyl group, a methoxy group, a methoxymethoxy group, Compounds in which R ¹ and R ³ are hydrogen atoms in a (2-methoxyethoxy)methoxy group or a [2-(trimethylsilyl)ethoxy]methoxy group are preferred. Among these compounds, compounds in which X ² is -CO-R ⁵ and R ⁵ is an isopropyl group, a butyl group, a tert-butyl group, or a cyclohexyl group are more preferred.

（式中、Ｒ^１ａは水素原子であり、Ｒ^２ａはメチル基、又は置換又は非置換のＣ_１－３－アルコキシ基であり、Ｒ^３ａは水素原子であり、Ｒ^４ａはメチル基、水酸基、ベンジルオキシ基、Ｃ_２－６－アルカノイルオキシ基、又は置換又は非置換のＣ_１－３－アルコキシ基であり；Ｘ^ａは－ＣＯ－又は－ＳＯ_２－であり；Ｒ^５ａは置換又は非置換の炭素数１～１０の炭化水素基、又は置換又は非置換のＣ_１－３－アルコキシ基である。）
で示される化合物（但し、Ｒ^１ａ及びＲ^３ａが水素原子であり、Ｒ^２ａ及びＲ^４ａがメチル基であり、Ｘ^ａが－ＣＯ－であり、Ｒ^５ａが非置換のイソプロピル基である化合物を除く）は新規化合物である。 Among the compounds represented by the formula (II), the following formula (IIa):

(In the formula, R ^1a is a hydrogen atom, R ^2a is a methyl group or a substituted or unsubstituted C _1-3 -alkoxy group, R ^3a is a hydrogen atom, R ^4a is a methyl group, a hydroxyl group, is a benzyloxy group, a C _2-6 -alkanoyloxy group, or a substituted or unsubstituted C _1-3 -alkoxy group; X ^a is -CO- or -SO ₂ -; R ^5a is substituted or unsubstituted is a hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted C _1-3 -alkoxy group.)
(However, a compound in which R ^1a and R ^3a are hydrogen atoms, R ^2a and R ^4a are methyl groups, X ^a is -CO-, and R ^5a is an unsubstituted isopropyl group) ) are new compounds.

The compound represented by the formula (I) can be produced, for example, as follows.
In the following, in the formula (II), R ¹ and R ³ are hydrogen atoms, R ² is a methyl group, R ⁴ is a [2-(trimethylsilyl)ethoxy]methoxy group, and X ² is -COCH(CH ₃ ) Compound ₂ will be explained as an example, but other compounds can also be produced according to the following method.

2-cyanophenol and a base (eg, potassium carbonate) are added to a solution of coumarin compound d in a ketone organic solvent (eg, 2-butanone) and reacted under heating to obtain compound f. Next, compound 26 can be obtained by adding a base (triethylamine) and isobutyryl chloride to a solution of compound f in an anhydrous organic solvent (for example, anhydrous dichloromethane) and allowing the reaction to occur under an inert gas atmosphere.

To purify the product obtained as described above, a commonly used method such as column chromatography using silica gel as a carrier or recrystallization method using methanol, ethanol, chloroform, dimethyl sulfoxide, water, etc. All you have to do is follow. Examples of elution solvents for column chromatography include methanol, ethanol, chloroform, acetone, hexane, dichloromethane, ethyl acetate, and mixed solvents thereof.

Furthermore, among the compounds represented by the formula (I), commercially available products can be used in the present invention.

The cytalone dehydratase (SDH1) inhibitor of the present invention contains at least one compound of formula (I) as its active ingredient. The compound of formula (I) has inhibitory activity against SDH1 and/or its amino acid variant (V75M variant), which is involved in the melanin production pathway of the rice blast fungus. Rice blast drug-resistant bacteria are said to exhibit drug resistance due to the V75M mutation in SDH1. Therefore, the SDH1 inhibitor of the present invention is also effective against drug-resistant bacteria of rice blast. More specifically, when the pesticidal agent of the present invention containing the compound of formula (I) is applied to rice blast fungi or its drug-resistant bacteria, the melanin production ability of rice blast fungi is suppressed, and as a result, the rice blast fungus is inhibited. can prevent invasion of plant cells. Among the compounds of formula (I), there are also compounds that have inhibitory activity against both SDH1 and its V75 mutant, or compounds that exhibit high inhibitory activity only against the V75 mutant. Although the details of this mechanism of action are not clear, the results of docking simulations indicate that the compound of formula (I) binds to SDH1 in the same manner as carpropamide, an existing SDH1-inhibiting rice blast control agent. However, it was suggested that the binding mode may be different from that of carpropamide. This property is presumed to be based on the common structure shown by the above formula (I).

It is preferable that the pesticidal agent of the present invention is provided in an appropriate dosage form using a carrier and, if necessary, adding an appropriate adjuvant. For example, it is preferable to formulate it into an oil, emulsion, powder, wettable powder, granule, suspension, etc., and dilute it appropriately before use.

Preferably used carriers include solid powders or granules of clay, talc, diatomaceous earth, clay, calcium carbonate, silicic anhydride, bentonite, sodium sulfate, silica gel, organic acid salts, sugars, starches, resins, synthetic or natural polymers, etc. Carriers, aromatic hydrocarbons such as xylene, aliphatic hydrocarbons such as kerosene, ketones such as methyl ethyl ketone, cyclohexanone, isophorone, lactams, ethers such as anisole, alcohols such as ethanol, propanol, ethylene glycol, etc. Examples include esters such as ethyl acetate and butyl acetate, and liquid carriers such as dimethyl sulfoxide, dimethylformamide, and water.

Furthermore, in order to ensure the effectiveness of the pesticidal agent, it is desirable to appropriately select and combine auxiliary agents such as emulsifiers, dispersants, wetting agents, binders, and lubricants depending on the purpose. Examples of such adjuvants include nonionic or ionic surfactants, carboxymethylcellulose, polyvinyl acetate, polyvinyl alcohol, gums, stearates, waxes, thickeners, and the like.

In the pesticidal agent of the present invention, the compound of the formula (I) is usually about 0.01 to 10% by mass in the case of a powder, preferably about 0.1 to 5% by mass in the case of a wettable powder. is about 1 to 90% by mass, preferably about 5 to 75% by mass, about 0.01 to 40% by mass in the case of granules, preferably about 0.1 to 20% by mass, and about 1 to 20% by mass in the case of liquids. The content is about 60% by mass, preferably about 5 to 40% by mass, and in the case of a suspending agent, about 1 to 80% by mass, preferably about 5 to 50% by mass.

The rice blast control agent of the present invention can of course be used alone, but it also includes blasticidin S, kasugamycin, tricyclazole, pyroquilon, isoprothiolane, fusaride, probenazole, methoxyacrylate type, benzthiadiazole type, and cyclopropane type. , pyrimidine series, dithiocarbamate series, carbamate series, benzimidazole series, benzthiazole series, triazine series, cyanoacetamide series, imidazole series, pyrrole series, nicotinoid series, guanidine series, nitromethylene series, cyanomethylene series, isothiazole series , anilide-based, quinoline-based, organochlorine-based, sulfonamide-based, pyrethroid-based, sulfonylurea-based, urea-based, organophosphorus-based compounds and other fungicides, insecticides, herbicides, plant growth regulators, or fertilizers. They can also be used in combination or as a mixture.

In addition, the pesticidal agent of the present invention includes at least one of the compounds represented by the formula (I) and at least one inhibitor of other enzymes involved in the melanin production pathway, specifically, polyketide synthase and It may further contain at least one compound having inhibitory activity against at least one enzyme. It can be blended in an optimal ratio depending on the distribution of viable bacteria in the soil etc. to which it is applied and the plant species.

The method for controlling rice blast of the present invention uses the compound represented by the formula (I) on the rice plant itself, its seeds, the field where it is growing or planned to grow, or its growth. The method includes a step of applying the method to a device to be used. More specifically, when the outbreak of rice blast disease is expected, the compound of the formula (I) is sprayed in advance on the rice stems and leaves, as well as on the rice roots, field surface, water surface, lateral stripes, soil, and seeds. , the compound of formula (I) is applied to seedling boxes and the like. Alternatively, after the disease has occurred and spread as a result of infection with the rice blast fungus, the disease can be eliminated or suppressed by using the compound of formula (I) as described above.

The amount of the pesticidal agent of the present invention to be applied is appropriately determined taking into account the form of the preparation and the method, purpose, and timing of application, but is usually calculated in terms of the amount of the compound of formula (I), which is the active ingredient. It is preferably applied in an amount of 10 to 2,000 g per ha, more preferably in a range of 50 to 1,000 g.

This specification includes the contents described in the specification and/or drawings of Japanese Patent Application No. 2019-048574, which is the basis of the priority of this application.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

All solvents used in the synthesis were of reagent grade. Anhydrous dichloromethane (CH ₂ Cl ₂ ) was obtained from Wako Pure Chemical.

Each reaction was monitored by thin layer chromatography (TLC) using 0.25 mm precoated silica gel plates (Merck KGaA).

Silica gel 60N (spherical; neutral; 0.04-0.05 mm) manufactured by Kanto Kagaku was used for flash chromatography.

¹ H NMR was performed using a JEOL JNM-ECA-500 (500 MHz) spectrometer in CDCl 3 with tetramethylsilane (0 ppm) as an internal standard or in CDCl ₃ as a solvent and an internal standard (3.30 ppm). Measured in _CD3OD . In each abbreviation, S means singlet, d means doublet, t means triplet, q means quartet, m means multiplet, and br means broad.

¹³ C NMR was measured in CDCl ₃ or CD ₃ OD as solvent and internal standard (77.0 or 49.0 ppm, respectively) using a JEOL JNM-ECA-500 (125 MHz) spectrometer.

Example 1: Synthesis example of compound 26 Compound 26 was synthesized by the following steps 1 to 4.

Step 1: Synthesis of 4-(chloromethyl)-5-hydroxy-7-methyl-2H-chromen-2-one (compound c)

Add 5 drops of ethyl 4-chloro-3-oxobutanoate (a) (2.47 g, 15 mmol) and 5-methylbenzene-1,3-diol (b) (1.24 g, 10 mmol) in toluene (40 mL). Concentrated sulfuric acid was added and heated at 85°C overnight. After cooling to room temperature, the precipitated solid was collected by filtration. The solid was washed with water and EtOAc and dried to obtain a pale yellow solid (1.23 g). Further, the organic layer was washed with water and saturated brine, dried over MgSO ₄ , and the solvent was distilled off under reduced pressure. The residue was heated again with concentrated sulfuric acid in toluene to give a pale yellow solid (0.81 g). Finally, the organic layer was washed with water and saturated brine, dried over MgSO ₄ , and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography (CHCl ₃ :MeOH=10:1) to obtain colorless compound c (0.05 g). The overall yield of compound c was 93.1%. Regarding step 1, a) Xie, L.; Takeuchi, Y.; Cosentino, LM; McPhail, AT; Lee, K.-HJ Med. Chem, 2001, 44, 664-671. b) Zak, Reference was made to the method described in J.; Ron, D.; Riva, E.; Harding, HP; Cross, BCS; Baxendale, IR Chem. Eur. J. 2012, 18, 9901-9910.
Compound (c): ¹ H NMR (500 MHz, CD ₃ OD) δ 2.33 (s, 3H), 5.09 (d, J = 1.0 Hz, 2H), 6.46 (brs, 1H), 6.58 (brs,, 1H) , 6.68 (brs, 1H).
^13C NMR (125 MHz, CD ₃ OD) δ 21.6, 45.9, 106.1, 109.5, 112.4, 113.2, 145.4, 154.4, 156.4, 157.1, 163.1.

Step 2: Synthesis of 4-(chloromethyl)-7-methyl-5-((2-(trimethylsilyl)ethoxy)methoxy)-2H-chromen-2-one (compound d)

Diisopropylethylamine (41.8 μL) was added to a solution of coumarin compound c (44.8 mg, 0.2 mmol) and 2-(trimethylsilyl)ethoxymethyl chloride (SEMCl) (42.6 μL, 2.4 mmol) in anhydrous CH ₂ Cl ₂ (5 mL). , 2.4 mmol) and stirred at room temperature under nitrogen atmosphere for 3 hours. The mixture was diluted with water-CH ₂ Cl ₂ . The organic layer was washed with water and saturated brine, dried over MgSO ₄ , and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography (n-hexane:EtOAc=2:1) to obtain a colorless oil (compound d) (42.0 mg, 59%). For step 2, reference was made to the method described in Lipshutz, BH; Pegram, JJ Tetrahedron Lett. 1980, 21, 3343-3346.
Compound d: ¹ H NMR (500 MHz, CDCl ₃ ) δ 0.02 (s, 9H), 0.99 (t, J = 8.0 Hz, 2H), 2.41 (s, 3H), 3.81 (t, J = 8.0 Hz, 2H ), 4.93 (d, J = 1.5 Hz, 2H), 5.19 (s, 2H), 6.54 (brs, 1H), 6.84 (brs, 1H), 6.88 (brs, 1H).
¹³ C NMR (125 MHz, CDCl ₃ ) δ -1.4, 18.0, 22.0, 45.4, 67.2, 93.5, 106.3, 110.8, 111.3, 114.1, 143.8, 150.6, 154.9, 155.1, 160.5.

Step 3: Synthesis of 4-(3-aminobenzofuran-2-yl)-7-methyl-5-((2-(trimethylsilyl)ethoxy)methoxy)-2H-chromen-2-one (compound f)

2-cyanophenol (282 mg, 2.4 mmol) and K ₂ CO ₃ (652 mg, 4.7 mmol) were added to a solution of coumarin compound d (420 mg, 1.2 mmol) in 2-butanone (20 mL), and the mixture was heated under reflux overnight. . After removing the solvent under reduced pressure, the residue was diluted with water and EtOAc. The organic layer was washed with water and saturated brine, dried over MgSO ₄ , and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography (benzene:acetonitrile=10:1) to obtain a colorless oil (compound f) (251 mg, 49%).
Compound f: ¹ H NMR (500 MHz, CDCl ₃ ) δ -0.06 (s, 9H), 0.77 (t, J = 8.0 Hz, 2H), 2.42 (s, 3H), 3.49 (t, J = 8.0 Hz, 2H), 4.96 (s, 2H), 6.45 (s, 1H), 6.86 (brs, 2H), 7.27 (ddd, J = 8.0, 8.0, 2.0 Hz, 1H), 7.35 (ddd, J = 8.0, 8.0, 1.0 Hz, 1H), 7.36 (dd, J = 8.0, 2.0 Hz, 1H), 7.53 (dd, J = 8.0, 1.0 Hz, 1H).
¹³ C NMR (125 MHz, CDCl ₃ ) δ -1.5, 17.9, 22.0, 66.7, 94.2, 106.8, 111.0, 111.3, 111.5, 113.6, 118.6, 122.1, 123.8, 125.9, 126.9, 134. 1, 142.3, 144.1, 153.3, 154.9, 155.6, 160.8.

Step 4: N-(2-(7-methyl-2-oxo-5-((2-(trimethylsilyl)ethoxy)methoxy)-2H-chromen-4-yl)benzofuran-3-yl)isobutyramide (compound 26 )

Triethylamine (159 μL, 1.14 mmol) and isobutyryl chloride (72 μL, 0.68 mmol) were added to a solution of coumarin compound f (250 mg, 0.57 mmol) in anhydrous CH ₂ Cl ₂ (10 mL). After stirring overnight at room temperature under nitrogen atmosphere, the mixture was diluted with water, EtOAc. The organic layer was washed with water and saturated brine, dried over MgSO ₄ , and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography (n-hexane:EtOAc=2:1) to obtain a colorless oil (Compound 26) (263 mg, 91%). For steps 3 and 4, a) Karn, IA Kurkarni, MV Gopal, M.; Shahabuddin, MS; Sun, C.-M. Bioorg. Med. Chem. Lett. 2005, 15, 3584-3587. b ) Frasinyuk, MS; Gorelov, SV; Bondarenkoo, SP; Khilya, VP Chem. Heterocyclic Compounds, 2009, 45, 1261-1269.
Compound 26: ¹ H NMR (500 MHz, CDCl ₃ ) δ -0.06 (s, 9H), 0.72 (t, J = 8.0 Hz, 2H), 1.22 (d, J = 7.0 Hz, 6H), 2.40 (s, 3H), 2.58 (qq, J = 7.0, 7.0 Hz, 1H), 3.39 (t, J = 8.0 Hz, 2H), 4.87 (s, 2H), 6.37 (s, 1H), 6.80 (brs, 1H), 6.82 (brs, 1H), 7.29 (dd, J = 8.0, 8.0 Hz, 1H), 7.35 (ddd, J = 8.0, 8.0, 1.0 Hz, 1H), 7.43 (brd, J = 8.0 Hz, 1H), 7.59 (brd,J = 8.0 Hz, 1H).
¹³ C NMR (125 MHz, CDCl ₃ ) δ -1.6, 17.7, 19.6, 22.1, 35.6, 66.7, 93.9, 106.7, 111.0, 111.3, 111.4, 116.2, 117.1, 120.8, 123.1, 125.1, 125.5, 141.7, 144.4, 144.7, 153.5, 154.4, 155.2, 160.3, 175.8.

In the above synthesis example, at least one of the reagent used in step 1 (compound b), the reagent SEMCl used in step 2, and the reagent isobutyryl chloride used in step 4 was replaced with the corresponding reagent, and the same procedure was carried out. The reaction proceeded to synthesize compounds 1 to 25 and 27 to 48, respectively.
Compounds 49-59 were obtained from Namiki Shoji.
Compounds 60 to 64 are compounds listed in the RIKEN Natural Compound Bank.

Example 2: Evaluation of SDH1 inhibitory activity In order to evaluate the inhibitory activity of each compound of formula (I) against SDH1 in the melanin biosynthesis pathway shown in FIG. 1, the following test was conducted. As SDH1, SDH1 derived from wild-type rice blast fungus and SDH1 (V75) derived from drug-resistant rice blast fungus were used. Note that SDH1 derived from the drug-resistant rice blast fungus is the V75M type in which valine at position 75 is replaced with methionine. The preparation and inhibitory activity measurements of these enzymes are described in Reference The test was carried out using the method described in "variant found in melanin biosynthesis dehydratase inhibitor (MBI-D) resistant strains of the rice blast fungus", Biosci. Biotechnol. Biochem. 68: 615-621 (2004)). Each compound shown in the table below was added at a predetermined concentration (0.3 nM to 30 μM), the concentration of citalone as a substrate was fixed at 50 μM, and the progress of the reaction was monitored by the increase in absorption at 352 nm. The activity (%) relative to the DMSO control was determined, and the concentration of each compound that showed 50% of the activity of the control was defined as IC ₅₀ . As a comparative example, a sample solution for a comparative example in which carpropamide (CPD; obtained from Wako Pure Chemical Industries, Ltd.; an existing SDH1 inhibitor) was added instead of the compound of formula (I) was evaluated in the same manner. As a result, the 50% inhibitory concentration (IC ₅₀ ) for SDH1 (WT type) was less than 3 nM, and the IC ₅₀ for SDH1 (V75M type) was 100 nM. From the results shown in the table, it can be seen that the compound of formula (I) has inhibitory activity against SDH1. Furthermore, it can be understood that some compounds have strong inhibitory activity against amino acid mutant SDH1, which can only be weakly inhibited by the existing inhibitor CPD.

Example 3: In vivo evaluation of melanization inhibitory activity against rice blast fungus Pyricularia oryzae Kita1 strain (NBRC30736 strain) was used as the wild type rice blast fungus. P. oryzae R2-1 or P. oryzae KR5-1 was used as the drug-resistant rice blast fungus. The R2-1 strain is a carpropamide-resistant bacterium isolated in Saga Prefecture, and has been confirmed to have a mutation from GTG to ATG (V75M mutation) in the SDH1 gene (see Document X above). The KR5-1 strain was created by replacing the SDH1 gene of the Kita1 strain with a drug-resistant type (V75M).

(Method 1)
Each well of a 24-well plate was filled with 500 μL of potato dextrose broth (PDB) + 0.1% agar medium (PDB (manufactured by Difco) with 0.1% agar added). Rice blast fungus was added to each well at a concentration of 2%, then each compound of the formula (I) was added to each well at 100 μM, cultured at 25°C for 7 days, and each sample culture solution I got it. As a control culture solution, a control culture solution (DMSO) was prepared in the same manner except that DMSO was added instead of the compound of formula (I), and carpropamide was added instead of the compound of formula (I). A control culture solution (CPD) was also prepared in the same manner except that the same concentration was added.

(Method 2)
In each well of a 24-well plate, 500 μL of CYA medium (Czapek-Dox Broth (manufactured by Difco) containing 0.5% yeast extract, 0.0001% ZnSO ₄ and 0.00005% CuSO ₄ ) was added to each well of a 24-well plate. filled with. Rice blast fungus was added to each well at a concentration of 2%, then each compound of the formula (I) was added to each well at 100 μM, cultured at 25°C for 7 days, and each sample culture solution I got it. In addition, as a control culture solution, a control culture solution (-) was prepared in the same manner except that the compound of formula (I) was not added, and a control culture solution (-) was prepared in the same manner except that DMSO was added instead of the compound of formula (I). A control culture solution (DMSO) prepared in the same manner as above, and a control culture solution (CPD) prepared in the same manner except that carpropamide was added at the same concentration in place of the compound of formula (I) above were also prepared. did.

(Method 3)
Into each well of a 24-well plate, 500 μL of PDB+Metal+0.1% agar medium (PDB (manufactured by Difco) with 0.0001% _ZnSO4 , 0.00005% _CuSO4 , and 0.1% agar added) filled with. Rice blast fungus was added to each well at a concentration of 2%, then each compound of formula (I) was added to each well at a concentration of 30 μM or 100 μM, and cultured at 25°C for 4 days. A culture solution was obtained. As a control culture solution, a control culture solution (DMSO) was prepared in the same manner except that DMSO was added instead of the compound of formula (I), and carpropamide was added instead of the compound of formula (I). A control culture solution (CPD) was also prepared in the same manner except that the same concentration was added.

If the melanin biosynthesis pathway in rice blast is functioning normally, melanin will be produced during cultivation and the culture solution will turn black. On the other hand, when SDH1, which is involved in the melanin biosynthesis pathway, is inhibited, the dehydration of Cytalon does not proceed, and as a result, melanin is not produced and the culture solution does not turn black. In this case, citalone accumulates during culture. For each sample culture solution and each control culture solution, it was observed whether the culture solution turned black, and then the accumulated amount of Citalone was measured using UPLC (manufactured by Waters).

The Kita1 strain was used as the rice blast fungus to be cultured, and evaluation was performed using any of Methods 1 to 3 above. In either method, it was visually confirmed that in the DMSO control (and control culture solution (-)) in which the melanin biosynthesis pathway was functioning normally, the culture solution turned black due to the production of melanin. On the other hand, it was visually confirmed that blackening was suppressed in each sample culture solution, similar to the control culture solution (CPD). Furthermore, as shown in Tables 2 to 4, accumulation of citalone was observed in the culture solution in which blackening was suppressed. From the above results, it was demonstrated in vivo that the compound of formula (I) suppresses melanin production against wild-type rice blast fungus and exhibits SDH1 inhibitory activity.

A drug-resistant rice blast fungus (R2-1 or KR5-1) was used as the rice blast fungus to be cultured, and evaluation was performed using any of Methods 1 to 3. In either method, it was visually confirmed that in the DMSO control (and control culture solution (-)) in which the melanin biosynthesis pathway was functioning normally, the culture solution turned black due to the production of melanin. On the other hand, it was visually confirmed that blackening of each sample culture solution was suppressed compared to the control culture solution (-). Furthermore, as shown in Tables 3 and 4, accumulation of citalone was observed in the culture solution in which blackening was suppressed. From the above results, it was demonstrated in vivo that the compound of formula (I) suppresses melanin production against drug-resistant rice blast fungi and exhibits inhibitory activity against amino acid mutant SDH1.

Example 4: Evaluation of control effect on rice Rice that is susceptible to the rice blast fungus Kita1 strain at the three-leaf stage (Nipponbare) was treated with a wild-type rice blast fungus (Kita1 strain) or a drug-resistant rice blast fungus (KR5-1). 20 mL of a spore suspension (suspended in 0.02% Tween 20 at 0.3 x 10 ⁴ per unit volume mL) of S. spores was ingested by spraying using an airbrush. 10 μM of the compound of formula (I) (compound 26) or CRP was added to the spore suspension. Also, as a control, a sample to which only DMSO was added was used. After infecting for 24 hours in an environment with a relative humidity of 100%, in the dark, and at a temperature of 25°C, each potato was infected in an artificial climate chamber for 6 days at 20°C with a light period of 14 hours and a dark period of 10 hours. The plants were allowed to grow until complete lesions of the disease developed. For each cultivated rice plant, the number of lesions appearing on the second to fourth leaves was counted to evaluate the occurrence of rice blast. Evaluation of pathogenicity was performed using 14 rice strains (2 pots) for each strain. The number of lesions per rice plant was expressed as mean ± standard deviation.

As shown in Figure 2, when applied to rice, carpropamide showed a high control effect against wild-type bacteria, but showed almost no activity against drug-resistant bacteria. On the other hand, it was demonstrated that Compound 26 exhibits a high control effect not only against wild type but also against drug-resistant rice blast fungi.

All publications, patents, and patent applications cited herein are incorporated by reference in their entirety.

Claims (11)

The following formula (I):

(In the formula, A ¹ to A ⁴ each represent CH or N; R is a substituent other than a hydrogen atom, n is an integer from 0 to 4, and when n is 2 or more, multiple R They may be the same or different, and R bonded to adjacent carbon atoms may be bonded to each other to form a ring; X ¹ and X ² are each a hydrogen atom, C _1-10 -alkyl group, -CO-R ⁵ , -CO-OR ⁵ or -SO ₂ -R ⁵ ; R ⁵ is a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted heterocyclic group )
A citalone dehydrase inhibitor containing at least one compound selected from the compounds shown below. In the formula (I), the substituent represented by R is a substituted or unsubstituted C _1-10 -alkyl group, a substituted or unsubstituted C _1-10 -alkoxy group, a substituted or unsubstituted C _6-10 The citalone dehydrase inhibitor according to claim 1, which is a -aryloxy group, a substituted or unsubstituted C _7-11 -aralkyloxy group, a halogen atom, or a hydroxyl group. The above formula (I) is the following formula (II):

(In the formula, either one of R ¹ and R ² is a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group, and R ¹ and R ² are The other is a hydrogen atom, a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group; R ³ and R ⁴ are a hydrogen atom, a hydroxyl group, a benzyl group, respectively; is an oxy group, ^a C _2-6 -alkanoyloxy group, a substituted or unsubstituted C _1-5 -alkyl group, or a substituted or unsubstituted C _1-5 -alkoxy group; ⁾
The citalone dehydrase inhibitor according to claim 1 or 2. The substituted or unsubstituted C _1-5 -alkoxy group in the formula (II) is a methoxymethoxy group, (2-methoxyethoxy)methoxy group, [2-(trimethylsilyl)ethoxy]methoxy group or benzyloxymethoxy group The citalone dehydratase inhibitor according to claim 3. The citalone dehydrase inhibitor according to any one of claims 1 to 4, which has an inhibitory activity against a non-wild type citalone dehydratase in which at least one amino acid is mutated. A rice blast control agent containing the citalone dehydrase inhibitor according to any one of claims 1 to 5. The rice blast control agent according to claim 6, further comprising at least one compound having inhibitory activity against at least one of polyketide synthase and reductase, which are involved in the melanin biosynthesis pathway of the rice blast fungus. The following formula (IIa):

(In the formula, R ^1a is a hydrogen atom, R ^2a is a methyl group or a substituted or unsubstituted C _1-3 -alkoxy group, R ^3a is a hydrogen atom, R ^4a is a methyl group, a hydroxyl group, is a benzyloxy group, a C _2-6 -alkanoyloxy group, or a substituted or unsubstituted C _1-3 -alkoxy group; X ^a is -CO- or -SO ₂ -; R ^5a is substituted or unsubstituted is a hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted C _1-3 -alkoxy group.)
A compound represented by (provided that R ^1a and R ^3a are hydrogen atoms, R ^2a and R ^4a are methyl groups, X ^a is -CO-, and R ^5a is an unsubstituted isopropyl group, Compounds in which R ^1a , R ^3a and R ^4a are hydrogen atoms, R ^2a is a methyl group, X ^a is -CO-, and R ^5a is an unsubstituted tert-butyl group, R ^1a and R ^3a is a hydrogen atom, R ^2a , R ^4a and R ^5a are methyl groups, and X ^a is -CO-, R ^1a and R ^3a are hydrogen atoms, and R ^2a and R ^4a are methyl groups. , a compound in which X ^a is -CO-, R ^5a is a 3,4,5-trimethoxyphenyl group, and R ^1a and R ^3a are hydrogen atoms, and R ^2a and R ^4a are methyl groups. , excluding compounds in which X ^a is -CO- and R ^5a is an unsubstituted cyclopropyl group ). The substituted or unsubstituted C _1-3 -alkoxy group in the formula (IIa) is a methoxymethoxy group, (2-methoxyethoxy)methoxy group, [2-(trimethylsilyl)ethoxy]methoxy group or benzyloxymethoxy group A compound according to claim 8. A step of applying the rice blast control agent according to claim 6 or 7 to the rice plant itself, its seeds, the field where it is growing or is planned to grow, or the equipment used for its growth. Methods for controlling rice blast, including: The rice blast control agent according to claim 6 or 7 is sprayed on rice stems and leaves, or the rice blast control agent is used to treat rice through roots, field treatment, water surface treatment, side strip treatment, soil treatment, rice seed treatment, or 11. The method according to claim 10, comprising the step of subjecting the seedling box to treatment.

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