Preparation method of tebuconazole and its intermediates

Abstract

This invention discloses a method for preparing cyclopentanone and its intermediates. Specifically, this invention discloses a method for preparing a compound as shown in formula (II), which includes the following steps: Step S1: In a solvent, under the action of a base, cyclopentanone undergoes a methylation reaction with a methylating agent to prepare a crude compound as shown in formula (I); Step S2: In a solvent, under the action of a base, the crude compound as shown in formula (I) undergoes a condensation reaction with p-chlorobenzaldehyde to prepare a compound as shown in formula (II).

Description

Technical Field

[0001] This invention relates to a method for preparing tebuconazole and its intermediates. Background Technology

[0002] Metconazole, commercially known as Caramba, is a triazole fungicide developed by Kureha Chemical Co., Ltd. of Japan in the early 1990s, in collaboration with BASF (now BASF). Metconazole possesses a broad antibacterial spectrum and strong systemic activity, exerting its fungicidal effect by inhibiting the C-14 demethylase cytochrome in sterol biosynthesis. It is primarily used to control diseases in cereal crops such as dwarf rust, leaf rust, yellow rust, crown rust, powdery mildew, glume blight, and diseases caused by *Syndromea* and *Fusarium*. It can also be used as a horticultural fungicide. Since its registration as a fungicide in France in 1994, the number of countries where it is registered has steadily increased, and it is now a registered pesticide in over 40 countries worldwide. In 2006, it was registered in Japan as a fungicide for wheat and turf. Currently, metconazole is widely used in Europe, North America, and South America as a fungicide for wheat, corn, rapeseed, and soybeans. As the world's population increases, the demand for food also continues to rise, leading to a surge in demand for pesticides. The demand for tebuconazole is expected to continue to expand in the future.

[0003] In the prior art, US Patent 7166750 of Kureha Chemical Co., Ltd. of Japan and Chinese Patent CN1454200A disclose a method for preparing 2,2-dimethyl-5-(4-chlorobenzyl)cyclopentanone. This method uses dimethyl adipate as the starting material and then proceeds through a series of reactions to obtain the intermediate of tebuconazole. The preparation route is shown below:

[0004] .

[0005] This method involves methylation in two stages, with the second methylation requiring sodium hydrogen hydride, making it highly hazardous. Furthermore, the synthetic route is lengthy and lacks industrial applicability.

[0006] CN104710372 discloses a method for preparing tebuconazole, which uses cyclopentanone as a raw material and reacts with p-chlorobenzaldehyde to obtain an exocyclic double bond α,β-unsaturated ketone, which is then methylated, catalytically hydrogenated and Johnson-Corey-Chaykovsky propylene oxide-treated, and finally reacted with 1,2,4-triazole to obtain tebuconazole.

[0007]

[0008] This route is relatively short, but the second step, dimethylation, has many byproducts and low yield, requiring silica gel column chromatography purification, which is not conducive to industrial-scale production. Summary of the Invention

[0009] The technical problem this invention aims to solve is the deficiency in existing methods for preparing 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone from cyclopentanone, which results in numerous byproducts requiring column chromatography purification, making industrial-scale production difficult. This invention provides a novel method for preparing 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone from cyclopentanone, eliminating the need for column chromatography purification, simplifying post-processing, and making it suitable for industrial-scale production.

[0010] In this invention, cyclopentanone, a readily available raw material, is first subjected to a methylation reaction. The crude product obtained from the methylation reaction is then reacted with p-chlorobenzaldehyde to prepare 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone. During the methylation reaction, byproducts are formed. and byproducts During the subsequent reaction with p-chlorobenzaldehyde, it will generate It can be removed by pulping, and Since it is a liquid and does not react with p-chlorobenzaldehyde, it can be removed by filtration. Therefore, when preparing 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone using the method of this invention, the product can be purified by filtration and recrystallization during post-processing, without the need for column chromatography separation and purification. This simple operation is beneficial for industrial production.

[0011] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0012] This invention provides a method for preparing a compound as shown in formula (II), comprising the following steps:

[0013] Step S1: In a solvent, under the action of a base, cyclopentanone undergoes a methylation reaction with a methylating agent to prepare a crude compound as shown in formula (I);

[0014]

[0015] Step S2: In a solvent, under the action of a base, the crude compound shown in formula (I) is subjected to a condensation reaction with p-chlorobenzaldehyde to prepare the compound shown in formula (II).

[0016] ,

[0017] In step S1, the solvent is a cyclic ether solvent, the base is sodium tert-butoxide and / or potassium tert-butoxide, and the methylating agent is methyl bromide and / or methyl iodoform; the molar ratio of cyclopentanone to the methylating agent is 1:(2~5), and the molar ratio of the base to the cyclopentanone is (2~5):1; the reaction temperature of the methylation reaction is -20~50℃.

[0018] In step S2, the solvent is an alkylbenzene solvent.

[0019] In certain preferred embodiments of the present invention, certain features of the preparation method are defined as follows, and features not mentioned are the same as those described in any embodiment of the present invention (hereinafter referred to as "in a certain embodiment of the present invention").

[0020] In one embodiment of the present invention, in step S1, the solvent is tetrahydrofuran.

[0021] In one embodiment of the present invention, in step S1, the molar ratio of the cyclopentanone to the methylating agent is 1:(2.5~3.5), for example 1:3.

[0022] In one embodiment of the present invention, in step S1, the molar ratio of the alkali to the cyclopentanone is (2~3):1, for example, 2.5:1.

[0023] In one embodiment of the present invention, in step S1, the volume-to-mass ratio of the solvent to the cyclopentanone is 5-15 mL / g, for example 8-12 mL / g, and more specifically 10 mL / g.

[0024] In one embodiment of the present invention, in step S1, the reaction temperature of the methylation reaction is 20~30℃, for example 25℃.

[0025] In one embodiment of the present invention, in step S1, the reaction solution after the complete methylation reaction of cyclopentanone with the methylating agent is concentrated to obtain a crude compound as shown in formula (I).

[0026] In one embodiment of the present invention, in step S1, the reaction solution after methylation reaction of cyclopentanone with a methylating agent is filtered, the filtrate is mixed with a water-insoluble organic solvent, washed with saturated brine, and concentrated to obtain a crude compound as shown in formula (I); preferably, the water-insoluble organic solvent is an ester solvent, such as ethyl acetate.

[0027] In one embodiment of the present invention, in step S1, the crude compound as shown in formula (I) further comprises and / or .

[0028] In one embodiment of the present invention, in step S2, the solvent is toluene.

[0029] In one embodiment of the present invention, in step S2, the alkali is an alkali metal hydroxide, such as sodium hydroxide.

[0030] In one embodiment of the present invention, in step S2, the volume-to-mass ratio of the solvent to the p-chlorobenzaldehyde is 1.5~3 mL / g, for example 2 mL / g.

[0031] In one embodiment of the present invention, in step S2, the molar ratio of p-chlorobenzaldehyde to cyclopentanone in step S1 is 1:(1~2), for example, 1:1.4.

[0032] In one embodiment of the present invention, in step S2, the molar ratio of the alkali to the cyclopentanone in step S1 is 1:(1~2), for example, 1:1.1.

[0033] In one embodiment of the present invention, after the reaction in step S2 is completed, post-processing is performed through the following steps: filtration and recrystallization.

[0034] Preferably, in the post-processing step, after filtration, the sample is washed with ethanol and then recrystallized with ethanol.

[0035] The present invention also provides a method for preparing a compound as shown in formula (III), wherein the compound as shown in formula (III) is... It includes the following steps:

[0036] The compound shown in formula (II) was prepared by the method described in any of the above schemes.

[0037] In a solvent, under the action of a base, the compound shown in formula (II), R3S + (=O)X - The compound was prepared by an addition reaction with 1,2,4-triazole as shown below, to give the compound shown in formula (III).

[0038]

[0039] In this case, R is independently H or methyl, and R is not simultaneously H, and X is a halogen.

[0040] In one aspect of the present invention, the solvent in the addition reaction is an amide solvent, such as N,N-dimethylformamide.

[0041] In one aspect of the present invention, in the addition reaction, the base is an alkali metal alkali ...

[0042] In one aspect of the present invention, in the addition reaction, the R3S + (=O)X - (CH3)3S + (=O)I - .

[0043] In one aspect of the present invention, in the addition reaction, the R3S + (=O)X - The molar ratio of the compound to that shown in formula (II) is (1~2):1, for example 1.1:1.

[0044] In one embodiment of the present invention, in the addition reaction, the molar ratio of the 1,2,4-triazole to the compound shown in formula (II) is (1~2):1, for example 1.2:1.

[0045] In one embodiment of the present invention, in the addition reaction, the molar ratio of the base to the compound as shown in formula (II) is (2~3):1, for example 2:1.

[0046] In one aspect of the present invention, in the addition reaction, the volume-to-mass ratio of the solvent to the compound as shown in formula (II) is 1 to 3 mL / g, for example, 2 mL / g.

[0047] In one aspect of the present invention, the reaction temperature of the addition reaction is 50~70°C, for example 60°C.

[0048] The reaction time of the reduction reaction is the conventional reaction time for such reactions in the art, until one of the raw materials reacts completely or no longer reacts.

[0049] In one embodiment of the present invention, the reaction time of the addition reaction is 8 to 12 hours, for example, 10 hours.

[0050] In one embodiment of the present invention, after the addition reaction is completed, post-processing is performed through the following steps, which include: mixing the reaction solution with water, filtering, and taking the filter cake.

[0051] This invention also provides a method for preparing tebuconazole, which includes the following steps:

[0052] The compound shown in formula (III) was prepared by the method described in any of the above schemes.

[0053] In a solvent, under the action of a catalyst, the compound shown in formula (III) undergoes a reduction reaction with a hydrogen source as described below to prepare tebuconazole.

[0054] .

[0055] In one embodiment of the present invention, in the reduction reaction, the solvent is selected from one or more of alcohol solvents, ester solvents and sulfoxide solvents, preferably alcohol solvents, ester solvents and sulfoxide solvents, and the volume ratio of the alcohol solvent, ester solvent and sulfoxide solvent can be (1~3): 1: (0.01~0.6), for example 2: 1: 0.02.

[0056] In one embodiment of the present invention, the alcohol solvent is ethanol.

[0057] In one embodiment of the present invention, the ester solvent is ethyl acetate.

[0058] In one embodiment of the present invention, the sulfoxide solvent is dimethyl sulfoxide.

[0059] In one embodiment of the present invention, the catalyst in the reduction reaction is palladium, and the palladium can be added to the reaction system in the form of palladium on carbon, for example, 10 wt% palladium on carbon.

[0060] In one aspect of the present invention, in the reduction reaction, the hydrogen source is hydrogen gas. Preferably, the amount of hydrogen gas is such that the hydrogen pressure of the reaction system is controlled at 1.5~2.5 atm, for example, 2 atm.

[0061] In one embodiment of the present invention, in the reduction reaction, the molar ratio of the catalyst to the compound shown in formula (III) is 1:(10~20), for example 1:17.

[0062] In one embodiment of the present invention, in the reduction reaction, the volume-to-mass ratio of the solvent to the compound as shown in formula (III) is 5 to 15 mL / g, for example, 10 mL / g.

[0063] In one aspect of the present invention, the reaction temperature of the reduction reaction is 0~50℃, for example 20~30℃, and more specifically 25℃.

[0064] The reaction time of the reduction reaction is the conventional reaction time for such reactions in the art, until one of the raw materials reacts completely or no longer reacts.

[0065] In one embodiment of the present invention, the reaction time of the reduction reaction is 6 to 10 hours, for example, 8 hours.

[0066] In one embodiment of the present invention, after the reduction reaction is completed, post-processing is performed through the following steps, which include: filtration, concentration, and recrystallization. The solvent for recrystallization may be selected from one or more of ethyl acetate, dichloromethane, and n-hexane, for example, ethyl acetate.

[0067] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0068] The reagents and raw materials used in this invention are all commercially available.

[0069] The significant advantages of this invention are as follows: In the preparation method of 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone using cyclopentanone as a raw material, column chromatography purification is unnecessary, post-processing is simple, and it is suitable for industrial-scale production. Furthermore, the preparation route for 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone provided by this invention significantly shortens the steps, eliminating the need for column chromatography purification at each step, simplifying post-processing, and facilitating operation, which is beneficial for industrial production. Detailed Implementation

[0070] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0071]

[0072] Example 1: Preparation of 2,2-dimethylcyclopentanone (I)

[0073] In a 250 mL reaction flask, tetrahydrofuran (100 mL), cyclopentanone (10 g, 118.9 mmol, 1.0 eq), sodium tert-butoxide (28.6 g, 297.2 mmol, 2.5 eq), and methyl bromide (48.9 g, 356.6 mmol, 3 eq) were added sequentially, and the mixture was stirred at 25 °C for 12 hours. Thin-layer chromatography with silica gel plate monitoring showed the reaction was complete. The mixture was filtered, the filtrate was concentrated, and the residue was diluted with ethyl acetate, washed successively with saturated brine, and dried over anhydrous sodium sulfate. The filtrate was filtered again and concentrated to obtain 2,2-dimethylcyclopentanone (10.8 g), a pale yellow oil, which was directly added to the next reaction. Gas chromatography was used to detect the formation of... and .

[0074] Example 2: 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone(II)

[0075] In a 100 mL reaction flask, toluene (25 mL), dimethylcyclopentanone (10.8 g), p-chlorobenzaldehyde (12.3 g, 87.4 mmol, 1.0 eq), and sodium hydroxide (4.2 g, 104.8 mmol, 1.2 eq) were added sequentially, and the mixture was stirred at room temperature for 3 hours. The reaction was monitored for completion using a silica gel plate for thin-layer chromatography. The mixture was filtered, and the solid was washed with ethanol to obtain a white solid. The solid was recrystallized from ethanol, filtered, and dried to give 14.7 g of 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone, with a two-step yield of 52%. LCMS: m / z 235.3, [M+H + HPLC: 98%.

[0076] 1 H-NMR (400MHz, CDCl3) δ 7.47-7.33 (m, 5H), 2.85-2.83 (m, 2H), 1.86-1.83 (m, 2H), 1.13 (s, 6H).

[0077] Example 3: 1-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-chlorobenzyl)-2,2-dimethylcyclopentanol(III)

[0078] Under nitrogen protection, in a 25 ml reaction flask, 10 ml of DMF, 1,2,4-triazole (1.8 g, 25.6 mmol, 1.2 eq), potassium tert-butoxide (4.8 g, 42.6 mmol, 2.0 eq), and trimethyl sulfoxide (5.2 g, 23.4 mmol, 1.1 eq) were added and stirred for 30 minutes. The condensation product, cyclopentanone(II) (5.0 g, 21.3 mmol, 1.0 eq), was then added, and the reaction was carried out at 60 °C for 10 h. The mixture was then cooled to room temperature, and the system was poured into water. A solid precipitated. After stirring for 1 hour, the mixture was filtered to obtain 4.2 g of a white solid, with a yield of 62%. LCMS: m / z 318.2, [M+H + ].

[0079] 1H-NMR (400MHz, CDC13) δ 8.11 (s, 1H), 7.83 (s, 1H), 7.21 (d, J=8.2Hz, 2H), 7.04 (d, J=8.2Hz, 2H), 5.58 (d, J=2.7Hz, 1H), 4.33 (d, J=14.0Hz, 1H), 4.20 (d, J=14.0Hz, 1H), 3.18 (s, 1H), 2.66-2.62 (m, 2H), 1.77-1.73 (m, 2H), 1.12 (s, 3H), 0.90 (s, 3H).

[0080] Example 4: Imidacloprid (IV)

[0081] 1-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-chlorobenzyl)-2,2-dimethylcyclopentanol (3 g, 9.4 mmol), a mixed solvent of ethanol / ethyl acetate / DMSO (30 mL, v / v ratio 2:1:0.02), 10% palladium on carbon (0.6 g, 0.56 mmol), and DMSO (0.5 mL) were added to a 50 mL hydrogen reactor. Hydrogen gas was introduced to 2 atm, and the reaction was carried out at 25 °C for 8 hours. The mixture was carefully filtered, the solvent was concentrated and evaporated, and the crude product was recrystallized from ethyl acetate to obtain 2.8 g of tebuconazole technical grade, yield 93%. LCMS: m / z 320.2, [M+H + ].

[0082] Recrystallization can also be performed using dichloromethane, n-hexane, or a variety of solvents including ethyl acetate, dichloromethane, and n-hexane.

[0083] 1 H-NMR(400MHz, CDCl3) δ 8.15(s, 1H), 7.98(s, 1H), 7.22 (d, J=8.2Hz,2H), 7.05 (d, J=8.2Hz, 2H), 4.30-4.14 (m, 2H), 3.64 (s, 1H), 2.52–2.44 (m,1H), 2.36–2.29 (m, 2H), 1.83–1.63 (m, 2H), 1.50–1.38 (m, 1H), 1.36–1.27 (m,1H), 1.02 (s, 3H), 0.68 (s, 3H).

[0084] Comparative Example 1: 5-(4-chlorobenzyl)-2,2-dimethylcyclopentanone (II) was prepared according to the method of patent CN104710372.

[0085] Under nitrogen protection, 2-(4-chlorobenzyl)cyclopentanone (1 g, 4.84 mmol, 1.0 eq), potassium tert-butoxide (2.2 g, 19.4 mmol, 4.0 eq), and THF (50 mL) were added to a dry 100 mL two-necked flask. After stirring at 25 °C for 0.5 hours, iodomethane (1.5 mL, 24.3 mmol, 5.0 eq) was added dropwise. After the addition was complete, the reaction was carried out at 25 °C for 12 hours. The HPLC control showed that the starting material reacted completely, the product was formed, and a considerable amount of byproducts were also formed. The reaction was stopped, water and ethyl acetate were added for separation, the organic layer was washed with water, dried, and concentrated to obtain the crude product. Recrystallization using organic solvents such as ethanol, ethyl acetate, and acetonitrile could not effectively improve the purity. Purification by silica gel column chromatography yielded 0.73 g of product, with a yield of 64%. LCMS: m / z 235.3, [M+H + ].

Claims

1. A method for preparing a compound as shown in formula (II), comprising the following steps: Step S1: In a solvent, under the action of a base, cyclopentanone undergoes a methylation reaction with a methylating agent to prepare a crude compound as shown in formula (I); ； Step S2: In a solvent, under the action of a base, the crude compound shown in formula (I) is subjected to a condensation reaction with p-chlorobenzaldehyde to prepare the compound shown in formula (II). ， In step S1, the solvent is tetrahydrofuran, the base is sodium tert-butoxide and / or potassium tert-butoxide, and the methylating agent is methyl bromide and / or methyl iodoform; the molar ratio of cyclopentanone to the methylating agent is 1:(2~5), and the molar ratio of the base to the cyclopentanone is (2~5):1; the reaction temperature of the methylation reaction is 20-30℃. In step S2, the solvent is toluene, the base is an alkali metal hydroxide, and the molar ratio of p-chlorobenzaldehyde to cyclopentanone in step S1 is 1:(1~2); the molar ratio of the base to cyclopentanone in step S1 is 1:(1~2). The raw materials for step S1 are the solvent, alkali, cyclopentanone and methylating agent.

2. The method for preparing the compound as shown in formula (II) according to claim 1, characterized in that, It meets one or more of the following conditions: (1) In step S1, the molar ratio of cyclopentanone to the methylating agent is 1: (2.5~3.5); (2) In step S1, the molar ratio of the alkali to the cyclopentanone is (2~3):1; (3) In step S1, the volume-to-mass ratio of the solvent to the cyclopentanone is 5-15 mL / g; (4) In step S1, the reaction solution after the methylation reaction of cyclopentanone and methylating agent is completed is concentrated to obtain the crude compound shown in formula (I). (5) In step S1, the crude compound as shown in formula (I) further comprises and / or ; (6) In step S2, the volume-to-mass ratio of the solvent to the p-chlorobenzaldehyde is 1.5~3 mL / g; (7) After the reaction in step S2 is completed, the following post-processing steps are performed: filtration and recrystallization.

3. The method for preparing the compound as shown in formula (II) according to claim 2, characterized in that, It meets one or more of the following conditions: (1) In step S1, the volume-to-mass ratio of the solvent to the cyclopentanone is 8-12 mL / g; (2) In step S1, the reaction solution after methylation reaction of cyclopentanone and methylating agent is filtered, the filtrate is mixed with water-insoluble organic solvent, washed with saturated brine, and concentrated to obtain crude compound as shown in formula (I). (3) In step S2, the volume-to-mass ratio of the solvent to the p-chlorobenzaldehyde is 2 mL / g; (4) In step S2, the molar ratio of p-chlorobenzaldehyde to cyclopentanone in step S1 is 1:1.

4. (5) In step S2, the molar ratio of the alkali to the cyclopentanone in step S1 is 1:1.1; (6) In the post-processing step after step S2, after filtration, the material is washed with ethanol and then recrystallized with ethanol.

4. A method for preparing a compound as shown in formula (III), wherein the compound as shown in formula (III) is... Its characteristics are, It includes the following steps: The compound shown in formula (II) is prepared by the method for preparing the compound as described in any one of claims 1 to 3; In a solvent, under the action of a base, the compound shown in formula (II), R3S + (=O)X - The compound was prepared by an addition reaction with 1,2,4-triazole as shown below, to give the compound shown in formula (III). ； Wherein, R is independently H or methyl, and R is not simultaneously H, and X is a halogen; In the addition reaction, the solvent is an amide solvent and the base is an alkali metal alkali ...

5. The method for preparing the compound as shown in formula (III) according to claim 4, characterized in that, It meets one or more of the following conditions: (1) In the addition reaction, the R3S + (=O)X - (CH3)3S + (=O)I - ; (2) In the addition reaction, the R3S + (=O)X - The molar ratio of the compound to that shown in formula (II) is (1~2):1; (3) In the addition reaction, the molar ratio of the base to the compound shown in formula (II) is (2~3):1; (4) In the addition reaction, the volume-to-mass ratio of the solvent to the compound shown in formula (II) is 1~3 mL / g; (5) The reaction time of the addition reaction is 8-12 hours; (6) After the addition reaction is completed, the following steps are performed for post-processing, which include: mixing the reaction solution with water, filtering, and taking the filter cake.

6. The method for preparing the compound as shown in formula (III) according to claim 5, characterized in that, It meets one or more of the following conditions: (1) In the addition reaction, the solvent is N,N-dimethylformamide; (2) In the addition reaction, the base is potassium tert-butoxide; (3) In the addition reaction, the R3S + (=O)X - The molar ratio of the compound to that shown in formula (II) is 1.1 : 1; (4) In the addition reaction, the molar ratio of the 1,2,4-triazole to the compound shown in formula (II) is 1.2:1; (5) In the addition reaction, the molar ratio of the base to the compound shown in formula (II) is 2:1; (6) In the addition reaction, the volume-to-mass ratio of the solvent to the compound shown in formula (II) is 2 mL / g; (7) The reaction temperature of the addition reaction is 60°C; (8) The reaction time of the addition reaction is 10h.

7. A method for preparing tebuconazole, characterized in that, It includes the following steps, The compound shown in formula (III) is prepared by the method for preparing the compound as described in any one of claims 1 to 6; In a solvent, under the action of a catalyst, the compound shown in formula (III) undergoes a reduction reaction with a hydrogen source as shown below to prepare tebuconazole. ； In the reduction reaction, the solvent is selected from one or more of alcohol solvents, ester solvents, and sulfoxide solvents; the reaction temperature of the reduction reaction is 0~50℃.

8. The method for preparing tebuconazole as described in claim 7, characterized in that, It meets one or more of the following conditions: (1) In the reduction reaction, the catalyst is palladium; (2) In the reduction reaction, the hydrogen source is hydrogen gas; (3) In the reduction reaction, the molar ratio of the catalyst to the compound shown in formula (III) is 1: (10~20); (4) In the reduction reaction, the volume-to-mass ratio of the solvent to the compound shown in formula (III) is 5-15 mL / g; (5) The reaction time of the reduction reaction is 6~10 h; (6) After the reduction reaction is completed, the following steps are performed for post-processing, including: filtration, concentration and recrystallization.

9. The method for preparing tebuconazole as described in claim 8, characterized in that, It meets one or more of the following conditions: (1) In the reduction reaction, the solvent is an alcohol solvent, an ester solvent, or a sulfoxide solvent; (2) The alcohol solvent is ethanol; (3) The ester solvent is ethyl acetate; (4) The sulfoxide solvent is dimethyl sulfoxide; (5) In the reduction reaction, the catalyst is palladium, and the palladium is added to the reaction system in the form of palladium on carbon; (6) In the reduction reaction, the hydrogen source is hydrogen gas, and the amount of hydrogen gas is such that the hydrogen pressure of the reaction system is controlled at 1.5~2.5 atm; (7) In the reduction reaction, the molar ratio of the catalyst to the compound shown in formula (III) is 1:17; (8) In the reduction reaction, the volume-to-mass ratio of the solvent to the compound shown in formula (III) is 10 mL / g; (9) The reaction time for the reduction reaction is 8 h; (10) After the reduction reaction is completed, the following steps are performed for post-processing, which include: filtration, concentration and recrystallization, wherein the solvent for recrystallization is selected from one or more of ethyl acetate, dichloromethane and n-hexane; (11) The reaction temperature of the reduction reaction is 20~30℃.

10. The method for preparing tebuconazole as described in claim 9, characterized in that, It meets one or more of the following conditions: (1) In the reduction reaction, the solvent is an alcohol solvent, an ester solvent and a sulfoxide solvent, and the volume ratio of the alcohol solvent, the ester solvent and the sulfoxide solvent is (1~3): 1: (0.01~0.6); (2) In the reduction reaction, the catalyst is palladium, and the palladium is added to the reaction system in the form of palladium on carbon, and the palladium on carbon is 10 wt% palladium on carbon; (3) In the reduction reaction, the hydrogen source is hydrogen gas, and the amount of hydrogen gas is such that the hydrogen pressure of the reaction system is controlled at 2 atm. (4) After the reduction reaction is completed, the following steps are performed for post-processing, including: filtration, concentration and recrystallization, wherein the solvent for recrystallization is ethyl acetate.

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