(19)
(11)EP 2 835 376 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
02.05.2018 Bulletin 2018/18

(21)Application number: 13773160.0

(22)Date of filing:  02.04.2013
(51)International Patent Classification (IPC): 
C07H 17/08(2006.01)
C07H 1/00(2006.01)
(86)International application number:
PCT/CN2013/073604
(87)International publication number:
WO 2013/149577 (10.10.2013 Gazette  2013/41)

(54)

NEW SYNTHESIS PROCESS OF ANTIPARASITIC DRUG SELAMECTIN

NEUES SYNTHESEVERFAHREN FÜR ANTIPARASITÄREN WIRKSTOFF SELAMECTIN

NOUVEAU PROCÉDÉ DE SYNTHÈSE DU MÉDICAMENT ANTIPARASITAIRE SÉLAMECTINE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 03.04.2012 CN 201210102405

(43)Date of publication of application:
11.02.2015 Bulletin 2015/07

(73)Proprietor: Zhejiang Hisun Pharmaceutical Co., Ltd.
Taizhou, Zhejiang 318000 (CN)

(72)Inventors:
  • YIN, Mingxing
    Taizhou Zhejiang 318000 (CN)
  • WU, Jianchao
    Taizhou Zhejiang 318000 (CN)
  • CHAI, Jian
    Taizhou Zhejiang 318000 (CN)

(74)Representative: Kador & Partner 
Corneliusstraße 15
80469 München
80469 München (DE)


(56)References cited: : 
WO-A1-99/07721
CN-A- 1 266 437
US-A- 5 981 500
WO-A1-2010/065852
CN-A- 1 724 553
  
  • Lu Shixiang: "The Synthesis of Selamectin and (R)-4-cyano-3-hydroxybutyric Acid Ethyl Ester - Master's thesis - Dissertation", , 1 January 2009 (2009-01-01), XP055220374, Retrieved from the Internet: URL:http://www.dissertationtopic.net/doc/5 94191 [retrieved on 2015-10-13]
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

Field of the invention



[0001] The present invention relates to synthesis process of antiparasitic drug, in particular, to new synthesis process of selamectin.

Background of the invention



[0002] Selamectin, has a chemical name of (5Z,25S)-25-cyclohexyl-4'-O-de(2,6-dideoxy-3-O-methyl-α-L-arabino-hexopyranosy l)-5-demethoxy-25-de(1-methylpropyl)-22,23-dihydro-5-(hydroxyimino)avermectin Ala (herein "a" indicates natural avermectin, in which the 25-substituent is (s)-sec-butyl, "A" indicates avermectin wherein the 5-substutient is methoxy, number "1" indicates avermectin wherein the double bond is at 22-23 position), and has a chemical formula of



[0003] Selamectin is produced by fermentation of new gene-recombined strain of Streptomyces avermitilis, and is a new compound belonging to avermectins. Such new generation antiparasitic drug is developed by Pfizer Inc., America, and is produced by structural modification of doramectin via chemical synthesis.

[0004] Selamectin has antiparasitic activity on both endoparasite (threadworm) and ectoparasite (arthropod insects). Having the same effect as other avermectins, selamectin causes rapid, lethal, and non-paralytic neuromuscular paralysis of insects by interfering the glutamic acid-controlling chloride ion channel of the insect. After being applied onto the skin of a cat or a dog, the drug is absorbed into blood, and a part of the drug enters into digestive tract and blood by oral when the animal grooms its hair. The pharmacokinetics results show that selamectin exhibits permanent absorption in blood plasma after topical external application. The experimental data show that selamectin accumulates on skin (in particular sebaceous gland), ensuring a permanent concentration of drug that is sufficient to kill parasitic on the hair. The skin scrapings collected 30 days after the application of the drug can still kill eggs and larva of flea. Therefore, in comparison to conventional similar drugs, selamectin can overcome the disadvantages of poor efficiency, easy recurrence, inconvenient, and poor resistance of pets, and can kill endoparasite and ectoparasite such as flea, heartworm, tick, Itch mite, and ear mite that afflict pet and their owners rapidly, efficiently, conveniently, and completely, and has high safety. Good effect can be obtained by either oral administration or injection.

[0005] The synthesis processes of selamectin are reported in the following references: US5981500, EP677054, WO94015944, and CN94101917, wherein selamectin is prepared from doramectin by hydrogenation, desugaring, oxidation and oximation. In the first step of hydrogenation, the compound of formula (II) is prepared by using Wilkinson's catalyst, and toluene as the solvent. The second step, desugaring, is carried out in isopropanol, using sulfuric acid. The third step, oxidation, is carried out in anhydrous ethyl ether, in the presence of active manganese dioxide. The fourth step, oximation, is carried out in anhydrous pyridine, using hydroxylamine hydrochloride. Finally, selamectin is obtained via purification by using silica gel column chromatography. Such process is the basic patented process for the preparation of selamectin, which has the disadvantages of long reaction route, low overall yield, and inconvenient industrial operation.
US6906184, EP1003764, WO99007721, CN98808106, etc. prepare selamectin via three-step chemical synthesis, using doramectin as the starting material. Firstly, the double bond at the C-22,23 position is converted into single bond by addition reaction, via hydrogenation. The second step is oxidation, only the hydroxyl group at C-5 position is oxidized to ketone. The third step is oximation and desugaring, i.e. the ketone at C-5 position is oximated, while a sugar molecule is desugared, to obtain selamectin. Such process is the improved process of the basic patented process, developed by Pfizer Inc., wherein the reaction that obtains 5-oxime from the intermediate of oxidation product and hydroxylamine hydrochloride, and the hydrolysis step generating monosaccharide derivatives are carried out simultaneously, as a single concurrent reaction, which simplify the operation process significantly, and can reduce the processing and separation process, and thus improve the overall yield and quality of selamectin. However, active manganese dioxide is employed as the oxidant in the second step, with significant amount, which is difficult for after-treatment, and thus the industrial production will bring significant environmental problems. Isopropanol/water system is employed in the third step, i.e. oximation and desugaring, it has long reaction time and is unsuitable for improving the efficiency of industrial production. WO 2010/065852 discloses the oxidation of 4"-, 4'- or 13-hydroxy group of avermectins using suitable oxidation conditions including but not limited to, oxalyl chloride/dimethyl sulfoxide.
Research On the Synthesis Process of Selamectin and Ethyl (R)-4-cyano-3-hydroxybutyrate (Shixiang Lv, Master's Thesis of Northeast Agricultural University, 2009) also uses doramectin as the starting material, wherein selamectin is synthesized via a three-step synthesis. The first step involves the preparation of the compound of formula (II) via catalytic hydrogenation, wherein the reaction condition is optimized, to obtain a yield of 95.8%. In the second step, i.e. oxidation, the intermediate II is prepared by oxidant A addition and oxidant A priming, respectively, and the yield is 93.4%. In the third step, i.e. oximation and desugaring, crude selamectin is obtained, and the optimized reaction conditions, i.e. triethylamine and 45°C, are determined by using triethylamine method and disodium hydrogen phosphate method, changing the reaction concentration, and carrying out reaction at room temperature, and then a yield of 75.5% is obtained. Finally, it is crystallized twice with solvent A, to obtain selamectin (purity >98.5%), and the overall yield is 55%. Such process is a successful improvement developed on the basis of the above mentioned two processes, and has the advantages of short reaction route and mild reaction conditions, and the overall yield is 55%. However, in the second step, i.e. oxidation, the oxidant after-treatment may generate a large amount of heavy metal wastewater, which may restrict the industrial production.

[0006] The present invention makes inventive development on the basis of the prior arts, overcomes the disadvantages of the above mentioned processes, and provides a novel synthesis scheme for selamectin, with easy-handled oxidant, short process period, high efficiency, and reduced pollution.

Description of the invention



[0007] One object of the present invention is to provide novel key intermediates of selamectin (the compound of formula (III) and the compound of formula (IV)) and the preparation method thereof; another object of the present invention is to provide a novel process for the preparation of selamectin according to the above mentioned intermediates.

[0008] In one aspect of the present invention, there provides novel intermediates that can be used in the synthesis of selamectin:





[0009] In another aspect of the present invention, there provides a method for the preparation of the compound of formula (III). The method includes the preparation of the compound of formula (III) from the compound of formula (II) via oxidation:



[0010] Preferably, dimethyl sulfoxide is used as the oxidant in the oxidation, which is carried out under the synergistic effect of dimethyl sulfoxide and an activator under basic condition. Wherein the activator is preferably selected from phenoxy phosphorodichloridate, oxalyl chloride, trifluoroacetic anhydride, acetic anhydride, and sulfur trioxide-pyridine complex, and the base is selected from triethylamine and N,N-diisopropylethylamine.

[0011] Also preferably, Dess-Martin reagent is used as the oxidant of the oxidation.

[0012] Preferably, the solvent in the oxidation is methylene dichloride, trichloromethane, toluene, acetone, and tetrahydrofuran.

[0013] Preferably, the reaction temperature is -78°C to 30°C.

[0014] Referring to Patent US6906184, the compound of formula (II) in the above mentioned oxidation is obtained by converting the double-bond at C-22,23 position into single bond, via addition of the double bond, under the effect of Wilkinson catalyst:



[0015] In another aspect of the present invention, there provides a method for the preparation of the compound of formula (IV), including the conversion of the compound of formula (III) and a nucleophilie into the compound of formula (IV) under acidic condition:



[0016] Preferably, the nucleophilic used in the reaction is water.

[0017] The reaction is carried out under acidic condition, wherein such acidic condition is preferably formed by acidic silica gel, C1-C8 monobasic acids, C2-C8 dibasic acids, or C4-C8 tribasic acids.

[0018] In the reaction, the compound of formula (III) preferably undergoes nucleophilic addition with the nucleophilie such as water under acidic condition, forming the addition product, a ketone-water compound, i.e. the compound of formula (IV). Such compound is thermodynamically unstable, and tends to be converted back into the former ketone by dehydration. Such addition is a reversible reaction, and the reaction equilibrium significantly tends to the reactant. During the separation process, the compound of formula (IV) tends to be converted back into the compound of formula (III) by dehydration, and thus is difficult to separate out. Also, the compound of formula (III) has equivalent effects with the compound of formula (IV), and thus there is no need to carry out purification.

[0019] In a further aspect of the present invention, there provides a method for the preparation of selamectin, including steps of forming selamectin from the compound of formula (III) or mixtures of the compound of formula (III) and (IV), via oximation and desugaring reaction:



[0020] Or



[0021] Preferably, the reaction is carried out in a homogeneous system formed by a C1-C3 alcohol and dioxane and water or a homogeneous system formed by a C1-C3 alcohol and water.
Preferably, the temperature of the reaction is 0-60°C.

[0022] A preferred synthesis scheme of selamectin is as follows, wherein dimethyl sulfoxide is used as the oxidant in scheme 1, and Dess-Martin reagent is used as the oxidant in scheme 2.



[0023] In the first step of the above mentioned reaction, doramectin is preferably dissolved using toluene, as the solvent. The reaction is carried out at a pressure of 0-10 kg and a temperature of 20-60°C, under the effect of Wilkinson catalyst, rhodium tris(triphenylphosphine) chloride (I), and reaches its end point after 1-48 h. The compound of formula (II) is separated by filtration and removing of the solvent.

[0024] In the second step, methylene dichloride is preferably used as the solvent, although other organic solvents such as methenyl trichloride, toluene, acetone, tetrahydrofuran, etc., can also be used. Dimethyl sulfoxide is added with stirring, and is cooled to about 0°C while stirring, and then triethylamine is added dropwise, the mixed solution is cooled to -35°C to 25°C after the addition of triethylamine is complete, and then phenoxy phosphorodichloridate is added dropwise, the temperature is maintained after the addition is complete. The reaction reaches its end point after about 0.5-4 h, and is quenched by adding aqueous solution of NaHCO3. The obtained reactant is subject to layered extraction, the organic phase is collected and then concentrated and dried to obtain the compound of formula (III), in the form of yellowish substance. The compound of formula (III) can be converted into the compound of formula (IV), in the presence of a nucleophilic reagent under acidic condition. However, the interconversion between the compound of formula (III) and the compound of formula (IV) will not influence the third step and the quality of the final product.

[0025] In the third step, hydroxylamine hydrochloride is reacted with the compound of formula (III) or the compound of formula (IV) or mixtures thereof, in 0-60°C water bath, for 1-48 h, to reach the end point, preferably under the effects of a mixed solvent of methanol/dioxane/water. Thereafter, methylene dichloride and water are added into the reaction liquid for extraction, the organic phase is collected and concentrated and dried, to obtain crude selamectin.

[0026] In comparison to prior arts, the present invention has the following advantages.

[0027] The present invention is a novel process developed on the basis of the processes described in prior art references, and overcomes the disadvantages of prior art processes and provides a novel method for the preparation of selamectin.

[0028] According to the present invention, selamectin is prepared via three-step chemical synthesis, using doramectin as the starting material. The first step, i.e. hydrogenation, involves the conversion of the double bond at the C-22, 23 position into single bond by addition reaction, under the effects of Wilkinson catalyst, with reference to US6906184. In the second step, i.e. oxidation, of the present invention, hydroxyl group at C-5 position is oxidized to ketone by using dimethyl sulfoxide, Dess-Martine reagent, etc., as the oxidant, while the hydroxyl group in C-4' sugar is oxidized to carbonyl, to obtain a novel intermediate for the preparation of selamectin. The oxidants are easy to after-treatment and have low pollution. The oximation and desugaring process in the third step, involves the oximation of the ketone at C-5 position, while C-4' desugars a sugar molecule, to obtain selamectin. In the present invention, the reaction period is significantly shortened by changing the types of the solvents. The processes according to the present invention is obviously superior to the hydrogenation, oxidation, oximation, and desugaring processes that described in the prior art references, rendering the overall yield of the present process is significantly improved, the present process period is shortened, the efficiency is significantly improved, and the pollution is reduced accordingly.

Examples



[0029] The following examples are provided for the purpose of describing all aspects of the present invention completely, in order to illustrate the specific embodiments of the present invention, but are not limiting.

Example 1


Hydrogenation reaction



[0030] 3L toluene was weighted into a clean and pressure-tested 5L hydrogenation tank, the feed valve was opened and 300g doramectin and 9g rhodium tris(triphenylphosphine) chloride (I) were added into the tank with stirring. The feed inlet was closed and the air in the tank was purged with nitrogen for 3 times.

[0031] The hydrogen valve was opened, in order to keep the pressure in the tank to 3 kg. The temperature was raised until the inner temperature of the tank was 50°C, and this temperature was kept for 1-6 h. The hydrogen pressure in the tank was removed after the hydrogenation was completed. It was purged with nitrogen for 3 times, and then emptying. And then, the bottom valve was opened, and the materials in the tank were transferred into a flask. The solvent was removed by filtration, and a compound of formula (II) was separated (288g, HPLC: 95.2%).

Example 2


Oxidation reaction



[0032] 100g compound of the above formula (II) was weighted and dissolved into 1 L methylene dichloride. 188 g Dess-Martin reagent was added with vigorous stirring. The reaction was held at room temperature for 2 h, until reached the end point. The product was filtered with the assistance of diatomaceous earth, in order to remove insoluble solid residue. 500 mL aqueous solution of NaHCO3/Na2S2O3 (1:1) was added into the filtrate for washing. The aqueous phase was again washed with 200 mL methylene dichloride for one time. The organic phases were combined and washed with water for one time, and then dried with anhydrous magnesium sulfate for 30 min. The solid was filtered off, and the filtrate was concentrated to obtain light yellowish compound of formula (III) (96g, HPLC: 89%).

[0033] The 1H NMR and 13C NMR data of the compound of formula (III) are determined as follows:
1H NMR (400 MHz, d-CDCl3) δ: 0. 81 (d, J=1.51 Hz, 3H), 0.87 (t, J=1.79, 3.69, 5.45 Hz, 1H), 1.19 (d, J=1.28, 1.63, 1.79, 2.57 Hz, 4H), 1.21 (m, J=1.51, 1.63, 1.79 Hz, 2H), 1.28 (m, J=1.79, 3.89, 4.43 Hz, 7H), 1.39 (t, J=1.99, 5.45 Hz, 1H), 1.51 (m, J=0.81, 1.21, 1.63, 3. 07 Hz, 10H), 1.63 (m, J=1.21, 1.28, 1.51, 2.31, 3.69, 4.81 Hz, 4H), 1.79 (m, J=0.87, 1.19, 1.21, 1. 28, 5.45Hz, 3H), 1.90 (t, 3H), 1.99 (m, J=1.39, 5.45 Hz, 1H), 2.14 (m, J=2.57, 4.19, 5.53 Hz, 1H), 2.31 (m, J=1.63, 3.69, 4.81, 5.02 Hz, 3H), 2.57 (m, J=1.19, 2.14, 3.96, 4.19, 5.53, 5. 76 Hz, 2H), 3.07 (d, J=1.51 Hz, 1H), 3.34 (t, J=3.69, 3.89 Hz, 1H), 3.44 (s, 3H), 3.51 (s, 3H), 3.58 (m, J=6.59 Hz, 1H), 3.69 (m, J=0.87, 1.63, 2.31, 3. 34 Hz, 2H), 3.86 (s, 1H), 3.89 (m, J=1.28, 3.34 Hz, 1H), 3.96 (s, J=2.57 Hz, 1H), 4.19 (m, J=2.14, 2.57 Hz, 1H), 4.43 (m, J=1.28 Hz, 1H), 4.74 (m, 2H), 4.81 (m, J=1.63 Hz, 1H), 5.02 (d, J=2.31 Hz, 1H), 5.45 (m, J=0.87, 1.39, 1.79, 1.99 Hz, 1H), 5.53 (d, J=2.14, 2.57 Hz, 1H), 5.76 (m, J=2.57, 5.95Hz, 2H), 5.95 (m, J=5.76 Hz, 1H), 6.59 (t, J=3.58 Hz, 1H); 13C NMR (400 MHz, d-CDCl3) δ: 13.91, 15.17, 15.43, 17.42, 18.36, 20.09, 24.73, 26.58, 27.00, 28.06, 30.66, 31.29, 34.14, 34.61, 35.67, 36.96, 38.57, 39.43, 39.85, 41.11, 46.62, 56.44, 58.32, 67.02, 67.10, 69.30, 69.85, 70.78, 78.05, 78.62, 79.19, 80.82, 81.16, 81.83, 81.92, 94.87, 97.51, 98.03, 118.41, 121.87, 124.70, 134.98, 136.82, 137.98, 138.99, 172.28, 192. 09, 205.92.

Example 3


Oxidation reaction



[0034] 100g compound of the above formula (II) was weighted and dissolved into 1 L methylene dichloride. 48.5 mL dimethyl sulfoxide was added with vigorous stirring. The solution was cooled to a temperature of -60°C with stirring, and then 62.6 mL trifluoroacetic anhydride, which had been diluted by methylene dichloride, was added dropwise. After addition, it was stirred for 30 min, and then 123 mL triethylamine was added into the reaction liquor dropwise. The reaction was held at -60°C for 2 h, until reached the end point. The reaction liquid was washed twice with 200 mL water. The organic phase was dried with anhydrous magnesium sulfate for 30 min. The solid was filtered off, and the filtrate was concentrated to obtain light yellowish compound of formula (III) (93g, HPLC: 85%).

Example 4


Oxidation reaction



[0035] 100g compound of the above formula (II) was weighted and dissolved into 1 L toluene. 46 mL dimethyl sulfoxide was added with vigorous stirring. The solution was cooled to a temperature of -65°C with stirring, and then 45.3 mL oxalyl chloride, which had been diluted by toluene, was added dropwise. After addition, it was stirred for 30 min at -65°C, and then the inner temperature was controlled and 120 mL triethylamine was added into the reaction liquor dropwise under such temperature. The reaction was held for 1 h, until reached the end point. The reaction liquid was washed with 5% sodium hydrogen carbonate for one time. The product was layered and the organic phase was washed with water again for one time and dried with anhydrous sodium sulfate for 1 h. The solid was filtered off, and the filtrate was concentrated to obtain light yellowish compound of formula (III) (95.2g, HPLC: 55.3%).

Example 5


Oxidation reaction



[0036] 100g compound of the above formula (II) was added into a clean 2 L four-neck flask and dissolved with 1.0 L methylene dichloride. 45 mL dimethyl sulfoxide was added into the four-neck flask with continuous stirring. The solution was cooled to a temperature of about 0°C with stirring, and then 86 mL triethylamine was added dropwis. After addition, the mixed solution was cooled to -35°C, and then 47 mL phhenoxy phosphorodichloridate solution, which has been diluted with 200 mL methylene dichloride, was added. After addition, the reaction was held at -30°C for 2 h, until reached the end point. And then 400 mL 5% aqueous solution of sodium hydrogen carbonate was weighted into the flask. It was stirred at room temperature for 30 min. The product was layered and the upper organic phase was collected. The aqueous phase was back-extracted with 300 mL methylene dichloride for one time.

[0037] The organic phases were combined and then washed with 400 mL water for one time, and dried with 100 g anhydrous sodium sulfate. The anhydrous sodium sulfate was filtered off, and the solvent was concentrated to dry at 45°C, to obtain light yellowish compound of formula (III) (95g, HPLC: 93%).

Example 6


Oxidation reaction



[0038] lOg compound of the formula (II) and 5.8 mL N,N-diisopropyl ethylamine were added into the mixed solvent of 20 mL anhydrous dimethyl sulfoxide and 80 mL anhydrous methylene dichloride. It was cooled to 0°C, and 5.3 g sulfur trioxide-pyridine complex was added with vigorous stirring. The reaction solution was raised to room temperature, and the stirring was continued until reached the end point. 50 mL saturated aqueous solution of sodium hydrogen carbonate and 20 mL methylene dichloride were added into the reaction liquid. It was held until layered, and the aqueous phase was back-extracted with 80 mL methylene dichloride. The methylene dichloride phases were combined, and were washed with 50 mL saturated aqueous solution of sodium hydrogen carbonate for one time and 50 mL saturated saline for one time, respectively, and then was dried over anhydrous magnesium sulfate for 30 min. It was filtered at reduced pressure, and concentrated, to obtain light yellowish compound of formula (III) (9.1g, HPLC: 85%).

Example 7


Oximation and desugaring reaction



[0039] 252 g the compound of formula (III) was dissolved into 1.8 L methanol and 1.8 L dioxane. Aqueous solution of 300 g hydroxylamine hydrochloride in 500 mL purified water was added with stirring. The inner temperature of the reaction liquid was raised to 40°C for 4 h, until reached the end point. 1 L water and 2 L methylene dichloride were added into the reaction liquid, in order to quench the reaction. It was layered and extracted. The aqueous phase was back-extracted with 400 mL methyleme dichloride. The organic phases were combined and washed with 400 mL water for one time. The organic phases were collected and dried over 100g anhydrous sodium sulfate, and then filtered under reduced pressure. The filtrate was concentrated to dry, to obtain crude selamectin (201g, HPLC: 81.2%).

Example 8


Oximation and desugaring reaction



[0040] 100g the compound of formula (III) was dissolved into 800 mL isopropanol. 100 g hydroxylamine hydrochloride in 200 mL water was added with stirring. The inner temperature of the reaction liquid was raised to 60°C for 2.5 h, until reached the end point. 1 L water and 400 mL methylene dichloride were added into the reaction liquid to quench the reaction. It was layered and extracted. The aqueous phase was back-extracted with 500 mL methyleme dichloride. The organic phases were combined and washed with 500 mL water for one time. The organic phases were collected and dried over 100g anhydrous sodium sulfate, and then filtered. The filtrate was concentrated to dry, to obtain crude selamectin (80g, HPLC: 65.2%).

Example 9


Oximation and desugaring reaction



[0041] 50g the compound of formula (III) was dissolved into 400 mL methanol and 400 mL dioxane, and the inner temperature was cooled to 10°C. 50 g hydroxylamine hydrochloride in 50 mL purified water was added with stirring. The inner temperature of the reaction liquid was controlled to 10°C±2°C for 168h, until reached the end point. 400 mL water and 1000 mL methylene dichloride were added into the reaction liquid to quench the reaction. It was layered and extracted. The aqueous phase was back-extracted with 200 mL methyleme dichloride for one time. The organic phases were combined and washed with 200 mL water for one time. The organic phases were collected and dried over 50g anhydrous sodium sulfate, and then filtered under reduced pressure. The filtrate was concentrated to dry, to obtain crude selamectin (46.8g, HPLC: 80.9%).

Example 10


Preparation of the compound of formula (IV) from the compound of formula (III)



[0042] 0.5 g the compound of formula (III) was weighted in a single-neck flask, and 4 mL acetonitrile and 1 mL water were added into the flask. Also, 0.25 g acidic silica gel was added into the flask at room temperature. It was stirred at room temperature for 3 h, and filtered to remove residues. The filtrate was collected and concentrated to obtain about 0.46g product, in the form of white solid. It is determined by HPLC that the content of the compound of formula (IV) is 16%, and that of the compound of formula (III) is 83.2%. The MS data of the compound of formula (IV) is as follows: MS (m/z): 936 [M+Na].

Example 11


Preparation of the compound of formula (IV) from the compound of formula (III)



[0043] 0.15 g the compound of formula (III) was weighted in a single-neck flask, and 2 mL acetonitrile and 1 mL water were added into the flask. Then a drop of 10% acetic acid was added into the flask at room temperature. It was stirred at room temperature for 2 h, and filtered to remove residues. The filtrate was collected and concentrated to obtain about 0.13g product, in the form of white solid. It is determined by HPLC that the content of the compound of formula (IV) is 12.3%, and that of the compound of formula (III) is 87.1%.

Example 12


Oximation and desugaring reaction



[0044] 0.2 g of the mixture of the compound of formula (III) and the compound of formula (IV), obtained from example 10, was dissolved into 2 mL methanol and 2 mL dioxane. 0.2 mL purified water and 0.2 g hydroxylamine hydrochloride were added with stirring. The inner temperature of the reaction liquid was raised to 40°C for 4h, until reached the end point. 5 mL water and 5 mL methylene dichloride were added into the reaction liquid to quench the reaction. It was layered and extracted. The aqueous phase was back-extracted with 5 mL methyleme dichloride for one time. The organic phases were combined and washed with 5 mL water for one time. The organic phases were collected and dried over 1 g anhydrous sodium sulfate, and then filtered under reduced pressure. The filtrate was concentrated to dry, to obtain crude selamectin (0.19g, HPLC: 78.6%).

Example 13


Preparation of the compound of formula (III) from the compound of formula (IV)



[0045] The aqueous acetonitrile solution of the compound of formula (IV) (HPLC content of 98.5%), prepared by reversed phase C18 silica gel, was converted into the compound of formula (III) by being concentrated at 40°C under reduced pressure.


Claims

1. A compound represented by the following formula (III)


 
2. A method for preparation of the compound of formula (III) according to claim 1, characterized in that the compound of formula (III) is prepared from the compound of formula (II) by oxidation reaction:

wherein,
an oxidant used in the oxidation reaction is Dess-Martin reagent or dimethyl sulfoxide and when using dimethyl sulfoxide the oxidation reaction is carried out under basic condition, in the presence of an activator.
 
3. The method according to claim 2, characterized in that the activator is selected from phenoxy phosphorodichloridate, oxalyl chloride, trifluoroacetic anhydride, acetic anhydride, and sulfur trioxide-pyridine complex, and the base is selected from triethylamine and N,N-diisopropylethylamine.
 
4. The method according to any one of claims 2-3, characterized in that a solvent used in the oxidation reaction is selected from dichloromethane, trichloromethane, toluene, acetone, and tetrahydrofuran, and a temperature for the oxidation reaction is -78°C to 30°C.
 
5. A mixture of a compound of formula (III) and a compound represented by the following formula (IV):


 
6. A method for preparation of the mixture of the compound of formula (III) and the compound of formula (IV) according to claim 5, characterized in that the compound of formula (III) is converted into the compound of formula (IV) with a nucleophilic reagent under acidic condition:


 
7. The method according to claim 6, characterized in that the nucleophilic reagent is selected from water, and the acidic condition is formed by acidic silica gel, C1-C8 monobasic acids, C2-C8 dibasic acids, or C4-C8 tribasic acids.
 
8. A method for preparation of selamectin, characterized in that the method comprises steps wherein a compound of Formula (III) or a mixture of a compound of formula (III) and a compound of formula (IV) is converted to selamectin by oximation and desugaring reaction:

or


 
9. The method according to claim 8, characterized in that a solvent used in the reaction is selected from a homogeneous system formed by a C1-C3 alcohol and dioxane and water or a homogeneous system formed by a C1-C3 alcohol and water, and a reaction temperature is 0-60°C.
 
10. The method according to any one of claims 8-9, characterized in that the compound of formula (III) is prepared by the method according to any one of claims 2-4.
 
11. The method according to any one of claims 8-9, characterized in that the mixture of the compound of Formula (III) and the compound of formula (IV) is prepared by the method according to any one of claims 6-7.
 
12. Use of a compound of formula (III) according to claim 1 and/or a mixture of a compound of formula (III) and a compound of formula (IV) in the preparation of selamectin.
 


Ansprüche

1. Verbindung, repräsentiert durch die folgende Formel (III)


 
2. Verfahren zum Herstellen von der Verbindung mit der Formel (III) nach Anspruch 1, dadurch gekennzeichnet, dass die Verbindung mit der Formel (III) mittels einer Oxidationsreaktion aus der Verbindung mit der Formel (II) hergestellt wird:

wobei
ein Oxidationsmittel, das in der Oxidationsreaktion verwendet wird, ein Dess-Martin-Reagenz oder Dimethylsulfoxid ist, und wenn Dimethylsulfoxid verwendet wird, die Oxidationsreaktion unter einer basischen Bedingung in Gegenwart von einem Aktivator durchgeführt wird.
 
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass der Aktivator aus Phenoxyphosphordichloridat, Oxalylchlorid, Trifluoressigsäureanhydrid, Essigsäureanhydrid und Schwefeltrioxid-Pyridin-Komplex und die Base aus Triethylamin und N,N-Diisopropylethylamin ausgewählt ist.
 
4. Verfahren nach einem der Ansprüche 2-3, dadurch gekennzeichnet, dass ein Lösungsmittel, das in der Oxidationsreaktion verwendet wird, aus Dichlormethan, Trichlormethan, Toluol, Aceton und Tetrahydrofuran ausgewählt ist und eine Temperatur für die Oxidationsreaktion -78 °C bis 30 °C beträgt.
 
5. Mischung aus einer Verbindung mit der Formel (III) und einer Verbindung, repräsentiert durch die folgende Formel (IV):


 
6. Verfahren zum Herstellen von der Mischung aus der Verbindung mit der Formel (III) und der Verbindung mit der Formel (IV) nach Anspruch 5, dadurch gekennzeichnet, dass die Verbindung mit der Formel (III) mit einem nukleophilen Reagenz unter sauren Bedingungen in die Verbindung mit der Formel (IV) konvertiert wird:


 
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass das nukleophile Reagenz aus Wasser ausgewählt ist und die saure Bedingung durch saures Silicagel, C1-C8 monobasische Säuren, C2-C8 dibasische Säuren oder C4-C8 tribasische Säuren gebildet wird.
 
8. Verfahren zum Herstellen von Selamectin, dadurch gekennzeichnet, dass das Verfahren Schritte umfasst, wobei eine Verbindung mit der Formel (III) oder eine Mischung aus einer Verbindung mit der Formel (III) und einer Verbindung mit der Formel (IV) durch Oximierung und Entzuckerungsreaktion zu Selamectin konvertiert werden:


 
9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass ein Lösungsmittel, das in der Reaktion verwendet wird, aus einem homogenen System, welches durch einen C1-C3 Alkohol und Dioxan und Wasser gebildet wird, oder einem homogenen System ausgewählt ist, welches durch einen C1-C3 Alkohol und Wasser gebildet wird, und eine Reaktionstemperaturen 0-60 °C beträgt.
 
10. Verfahren nach einem der Ansprüche 8-9, dadurch gekennzeichnet, dass die Verbindung mit der Formel (III) durch das Verfahren nach einem der Ansprüche 2-4 hergestellt wird.
 
11. Verfahren nach einem der Ansprüche 8-9, dadurch gekennzeichnet, dass die Mischung aus der Verbindung mit der Formel (III) und der Verbindung mit der Formel (IV) durch das Verfahren nach einem der Ansprüche 6-7 hergestellt wird.
 
12. Verwendung von einer Verbindung mit der Formel (III) nach Anspruch 1 und/oder einer Mischung aus einer Verbindung mit der Formel (III) und einer Verbindung mit der Formel (IV) bei der Herstellung von Selamectin.
 


Revendications

1. Composé représenté par la formule (III) suivante :


 
2. Procédé pour la préparation du composé de formule (III) selon la revendication 1, caractérisé en ce que le composé de formule (III) est préparé à partir du composé de formule (II) par une réaction d'oxydation :

dans lequel un oxydant utilisé dans la réaction d'oxydation est un réactif de Dess-Martin ou le diméthylsulfoxyde et, lors de l'utilisation de diméthylsulfoxyde, la réaction d'oxydation est mise en oeuvre dans des conditions basiques, en présence d'un activateur.
 
3. Procédé selon la revendication 2, caractérisé en ce que l'activateur est choisi parmi le phénoxyphosphorodichlorurate, le chlorure d'oxalyle, l'anhydride trifluoroacétique, l'anhydride acétique, et un complexe de trioxyde de soufre et de pyridine, et la base est choisie parmi la triéthylamine et la N,N-diisopropyléthylamine.
 
4. Procédé selon l'une quelconque des revendications 2 et 3, caractérisé en ce qu'un solvant utilisé dans la réaction d'oxydation est choisi parmi le dichlorométhane, le trichlorométhane, le toluène, l'acétone, et le tétrahydrofurane, et la température pour la réaction d'oxydation va de -78°C à 30°C.
 
5. Mélange d'un composé de formule (III) et d'un composé représenté par la formule (IV) suivante :


 
6. Procédé pour la préparation d'un mélange du composé de formule (III) et du composé de formule (IV) selon la revendication 5, caractérisé en ce que le composé de formule (III) est converti en le composé de formule (IV) avec un réactif nucléophile dans des conditions acides :


 
7. Procédé selon la revendication 6, caractérisé en ce que le réactif nucléophile est l'eau, et la condition acide est formée par du gel de silice acide, des acides monobasiques en C1 à C8, des acides dibasiques en C2 à C8, ou des acides tribasiques en C4 à C8.
 
8. Procédé pour la préparation de sélamectine, caractérisé en ce que le procédé comprend des étapes dans lesquelles un composé de formule (III) ou un mélange d'un composé de formule (III) et d'un composé de formule (IV) est converti en sélamectine par une réaction d'oximation et de désucrage :

ou


 
9. Procédé selon la revendication 8, caractérisé en ce qu'un solvant utilisé dans la réaction est choisi parmi un système homogène formé par un alcool en C1 à C3 et du dioxane et de l'eau, et un système homogène formé par un alcool en C1 à C3 et de l'eau, et la température réactionnelle est de 0 à 60°C.
 
10. Procédé selon l'une quelconque des revendications 8 et 9, caractérisé en ce que le composé de formule (III) est préparé par le procédé selon l'une quelconque des revendications 2 à 4.
 
11. Procédé selon l'une quelconque des revendications 8 et 9, caractérisé en ce que le composé de formule (III) et le composé de formule (IV) sont préparés par le procédé selon l'une quelconque des revendications 6 et 7.
 
12. Utilisation d'un composé de formule (III) selon la revendication 1 et/ou d'un mélange d'un composé de formule (III) et d'un composé de formule (IV) dans la préparation de sélamectine.
 






Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description




Non-patent literature cited in the description