KR910005055B1 - 4-chloro-2-formylimino-3-methyl benzo thiazol and its process for preparation - Google Patents

Abstract

4-Chloro-2-formylimino-3-methylbenzothiazole of formula (I) is prepd. by reacting 4-cyloro-2-imino-3-methylbenzothiazole of formula (II) with N,N- dimethylformamide and a methylating agent in the presence of an acid catalyst. Pref. the acid catalyst is HAC, formic acid oxalic acid, p-toluenesulfonic acidd, HCl, H2SO4, HBr HNO3, and the methylating agent is dimethylsulfate, trimethylphosphate, iodomethane, bromomethane or chloromethane. (I) may be used as an agricultural medicine.

Description

Novel 4-chloro-2-formylimino-3-methylbenzothiazole and preparation method thereof

1 is an infrared absorption spectrum of a compound according to an embodiment of the invention.

The present invention relates to a novel 4-chloro-2-formylimino-3-methylbenzothiazole compound represented by the following structural formula (I), a preparation method thereof, and its application to agrochemical fields.

The compound (I) is useful as an intermediate in the synthesis of 4-chloro-3-methylbenzothiazol-2-one represented by the following structural formula (II), and the compound (II) is particularly resistant to rice blast and stem rot. It is widely known that it is very effective in controlling, and there are already various methods for producing the same.

For example, JP-A-2801868 discloses a diazotization reaction and a chlorination reaction using 2-amino-4-chlorobenzothiazole represented by the following structural formula (III) as the starting material, to the following structural formula (IV). A method of preparing 4-chloro-3-methylbenzothiazol-2-one of formula (II) is disclosed by synthesizing the indicated 2,4-dichlorobenzothiazole, followed by a thermal potential reaction using a catalyst. have.

In addition, JP-A-82-6953 and 82-6972 disclose the reaction of 2-chloro-N-methylaniline represented by the following structural formula (V) with chlorocarbonylsulphenyl chloride represented by the following structural formula (VI). N- (2-chlorophenyl) -N-methylcarbamoyl sulfen chloride represented by the following Structural Formula (VIII) was prepared, and cyclization was performed again to obtain 4-chloro-3- of Structural Formula (II). A method of preparing methylbenzothiazol-2-one is proposed.

However, in the case of preparing 4-chloro-3-methylbenzothiazol-2-one of formula (II) according to the conventional method as described above, the reaction process is complicated and the reaction time is long, and operation is difficult. In addition, the resulting product has a lower purity (30-80%) and lower purity (30-80%) of the final product was difficult to practical application in the industry.

Thus, in the present invention, 4-chloro-3-methylbenzothiazol-2-one of formula (II), which is useful in the field of agrochemicals, can be easily prepared in high purity and high yield. An object of the present invention is to provide 4-chloro-2-formylimino-3-methylbenzothiazole of formula (I), a method of preparing the same, and a method of using the same as a synthetic intermediate.

Hereinafter, the present invention will be described in detail.

The present invention is a 4-chloro-2-formylimino-3-methylbenzothiazole compound represented by the following structural formula (I).

The present invention also provides an acid catalyst for 2-amino-4-chlorobenzothiazole represented by the following structural formula (III) or 4-chloro-2-imino-3-methylbenzothiazole represented by the following structural formula (iii). The reaction is carried out with N, N-dimethylformamide (DMF) and a methylating agent below to prepare 4-chloro-2-formylimino-3-methylbenzothiazole of formula (I).

In addition, the present invention is the following structural formula (II) effective to control 4-chloro-2-formylmino-3-methylbenzothiazole represented by the structural formula (I) prepared as described above for rice fever and stem rot disease It is a method used as an intermediate for synthesizing 4-chloro-3-methylbenzothiazol-2-one represented by.

In this case, the compound (II) is prepared by hydrolyzing the compound (I).

Hereinafter, the present invention will be described in more detail.

In the present invention, 4-chloro-2-formylimino of the formula (I) by reacting the compound of formula (III) or formula (VII) with N, N-dimethylformamide and a methylating agent in the presence of an acid catalyst 4-Chloro-3 of Structural Formula (II) having a purity of 98% or more by only one step reaction of simply hydrolyzing the compound of Structural Formula (I) prepared in this way with high yield. The methylbenzothiazol-2-one compound can be easily produced in high yield of 90% or more.

In the present invention, an organic acid such as acetic acid, formic acid, oxalic acid p-toluenesulfonic acid, or an inorganic acid such as hydrochloric acid, sulfuric acid, bromic acid, or nitric acid may be used as the acid catalyst, and the amount of the acid catalyst is used in the compound of formula (III) or (iii). If the acid catalyst is used in an amount of 0.05 to 5.0 mole times, the acid catalyst may be used in an amount of 5.0 mole times or more, so that a large amount of side reaction products are generated. In the case of using a small amount, there are disadvantages such as a slow progress of the reaction.

In addition, suitable methylating agents for use in the present invention include dimethyl sulfate trimethyl phosphate, iodomethane, bromomethane, chloromethane and the like, the amount of which is 1.0 to 10.0 mol based on the compound of formula (III) It is preferable to use it by double.

In addition, the said reaction temperature is 0 degreeC or more, Preferably it is good to carry out at the temperature of room temperature to 150 degreeC.

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

Example 1

Preparation of 4-chloro-2-formylmino-3-methylbenzothiazole

18.47 g (0.10 mol) of 2-amino-4-chlorobenzothiazole is dissolved in 200 ml of N, N-dimethylformamide, which is 9.51 g (0.05 mol) of p-toluene sulfonic acid and 50.45 g (0.40) of dimethyl sulfate. Mole) and then heated. The solution is stirred at a temperature of 135 ° C. for 3 hours, distilled to remove N, N-dimethylformamide, the solution is cooled, neutralized with basic aqueous solution and extracted with ethyl acetate. The solvent was then removed by distillation under reduced pressure, followed by column chromatography [silica gel, solvent (N-hexane: ethyl acetate = 3: 1)] to give 21.54 g of the target compound (yield: 93.5%, purity: 98.1%). Got it.

At this time, purity was measured by gas chromatography.

Property test

1) m.p: 186 ~ 188 ℃

2) Molecular Weight: 226.68

3) Appearance: Light yellow powder

4) Elemental Analysis: C ₉ H ₇ ClN ₂ O

Theoretical (%): N; 12.36, C; 47.69, H; 3.11

Found (%): N; 12.47, C; 47.61, H; 3.49

5) ¹ H-NMR (CDCl ₃ ), δ (ppm); 4.29 (3H, S), 7.10 ~ 7.60 (3H, m), 9.07 (1H, s)

6) ¹³ C-NMR (CDCl ₃ ), δ (ppm); 36.358, 118.627, 212.454, 124.622, 129.154, 129.885, 133.102, 167.511, 171.556

7) Infrared (IR) absorption spectrum: shows the same result as in FIG.

Example 2

Preparation of 4-chloro-2-formylmino-3-methylbenzothiazole

19.80 g (0.1 mol) of 4-chloro-2-imino-3-methylbenzothiazole is dissolved in 200 ml of N, N-dimethylformamide, which is 9.51 g (0.05 mol) of p-toluenesulfonic acid and dimethyl 12.61 g (0.10 mol) of sulphate is added and then heated. The solution was stirred at a temperature of 130 ° C. for 5 hours, distilled to remove N, N-dimethylformamide, then the solution was cooled and neutralized with a basic aqueous solution, followed by the same method as in Example 1 above. To obtain 21.78 g (yield: 94.4%, purity: 98.0%) of the target compound as a light yellow powder. At this time, purity was measured by gas chromatography.

Example 3

Preparation of 4-chloro-3-methylbenzothiazol-2-one

22.67 g (0.1 mol) of 4-chloro-2-formylimino-3-methylbenzothiazole prepared in Examples 1 and 2 was dissolved in 100 ml of N, N-dimethylformamide, and p- 1.90 g (0.01 mol) of toluenesulfonic acid, 12.61 g (0.10 mol) of dimethyl sulfate and 3.60 g (0.2 mol) of distilled water are added and heated. The solution was refluxed for 5 hours, then N, N-dimethylformamide was removed by distillation and then cooled and extracted with toluene.

Thereafter, the organic layer was removed by solvent distillation under reduced pressure, and the white solid thus obtained was recrystallized with ethanol to obtain 19.73 g of the target compound as a white needle (yield: 97.41%, purity: 98.5%). At this time, purity was measured by gas chromatography.

Claims (7)

4-Chloro-2-formylimino-3-methylbenzothiazole compound represented by the following structural formula (I).

The following structural formula (I) is characterized by reacting 4-chloro-2-imino-3-methylbenzothiazole represented by the following structural formula (i) with N, N-dimethylformamide and a methylating agent in the presence of an acid catalyst. Method for producing 4-chloro-2-formylimino-3-methylbenzothiazole as indicated.

The method of claim 2, wherein the acid catalyst is selected from organic acids such as acetic acid, formic acid, oxalic acid, and p-toluenesulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, bromic acid, and nitric acid. The method according to claim 2, wherein the methylating agent is selected from dimethylsulfate, trimethylphosphate, iodomethane, bromomethane and chloromethane. The method according to claim 2, wherein the acid catalyst is used in an amount of 0.05 to 5.0 mole times with respect to 4-chloro-2-imino-3-methylbenzothiazole represented by the structural formula (i). The method according to claim 2, wherein the methylating agent is used in an amount of 1.0 to 10.0 mole times with respect to 4-chloro-2-imino-3-methylbenzothiazole represented by the structural formula (i). 4-chloro-2-formylimino-3-methylbenzothiazole represented by the following structural formula (I) is effective for the control of rice fever and stem rot, 4-chloro-3-methyl represented by the following structural formula (II) Use as an intermediate for synthesizing benzothiazol-2-one.

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