Intermediate and crystalline form of JAK inhibitor, and preparation method

Abstract

The present application discloses an intermediate of a JAK inhibitor Ilunocitinib represented by formula (I) and a preparation method therefor, a method for preparing the JAK inhibitor Ilunocitinib, and a crystalline form of the JAK inhibitor. The method for preparing Ilunocitinib by using the intermediate uses cheap and easily available starting materials for synthesis, does not use a precious catalyst, does not involve the introduction and removal of a protective group, has short process steps, mild reaction conditions, a high yield, and low costs, and is safe and environmentally friendly, thereby being suitable for industrial large-scale production.

Description

Intermediates, crystal forms and preparation methods of JAK inhibitors Technical Field

[0001] This application belongs to the field of pharmaceutical chemical synthesis technology, specifically involving intermediates, crystal forms, and preparation methods of JAK inhibitors. Background Technology

[0002] Ilunocitinib has the following structure and its chemical name is 2-{3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]-1-(cyclopropylsulfonyl)azacyclobutane-3-yl}acetonitrile:

[0003] Iruxitinib is a non-selective JAK (Janus Kinase) inhibitor developed by animal health giant Elanco Animal Health. It was approved for marketing in the United States by the U.S. Food and Drug Administration (FDA) on September 19, 2024, under the brand name Zenrelia. TM This product is a safe, effective, and convenient once-daily oral JAK inhibitor for controlling itching associated with atopic dermatitis and for controlling atopic dermatitis (AD) in dogs at least 12 months of age. In one study, Zenrelia was shown to be as effective as existing JAK inhibitors on the market. TM It achieved clinical relief of itching in 77% of dogs. The product has also received initial approval from the Brazilian Ministry of Agriculture, Livestock and Food Supply, with a planned market launch in the fourth quarter of 2024. Furthermore, market approval is underway in nine other markets, including Canada, Europe, the UK, and Japan.

[0004] Existing reports on the synthesis methods of iruxitinib are mainly found in: US8158616B2, WO2020219524, WO2022087515, etc., and these methods generally involve the intermediate shown in the figure below:

[0005] Where R is

[0006] US Patent 8158616B2 discloses a method for preparing iruxitinib from 4-chloro-7H-pyrrolo[2,3-d]pyrimidine as a starting material. This method has a long route, low overall yield, and involves multiple steps of preparative chromatographic purification, generating significant amounts of waste, making it unsuitable for commercial scale-up production. Furthermore, the introduction of the pyrazole ring requires an expensive palladium catalyst, and the synthetic route involves the introduction and removal of multiple protecting groups, resulting in poor atom economy. The specific route is shown below:

[0007] R 1 for R 2 for

[0008] Patent applications WO2020219524 and WO2022087515 also disclose a method for preparing iruxitinib using 4-chloro-7H-pyrrolo[2,3-d]pyrimidine as a starting material. This method has a moderate route length and a relatively high overall yield, making it feasible for scale-up production. However, the introduction of the pyrazole ring requires the use of an expensive palladium catalyst, and the synthetic route also involves the introduction and removal of protecting groups, resulting in poor atom economy. The specific route is shown below:

[0009] R 3 It is tert-butyloxycarbonyl.

[0010] In summary, current methods for synthesizing iruxitinib generally require expensive reagents, involve the introduction and removal of protecting groups, have cumbersome post-processing, poor atom economy, and low overall yield, which are not conducive to commercial production. Therefore, better methods are needed to meet the production requirements of iruxitinib. Summary of the Invention

[0011] To address the problems existing in the prior art, this application proposes a key intermediate for preparing the JAK inhibitor iruxitinib and its preparation method, as well as a method for preparing the JAK inhibitor iruxitinib using the intermediate, and a crystal form of the JAK inhibitor. The method for preparing iruxitinib in this application uses inexpensive and readily available raw materials, does not use expensive catalysts, does not involve the introduction and removal of protecting groups, has short process steps, mild reaction conditions, high yield, low cost, is safe and environmentally friendly, and is suitable for large-scale industrial production.

[0012] This application provides, in one aspect, a compound of formula I or a pharmaceutically acceptable salt thereof:

[0013] In some embodiments, a pharmaceutically acceptable salt of the compound of formula I is a compound of formula Ia;

[0014] Where HY is acid, and n is any value from 0 to 4 (e.g., n is 1, 2, 3 or 4).

[0015] In some embodiments, HY is selected from hydrochloric acid, hydrobromic acid, nitric acid, phosphoric acid, metaphosphoric acid, sulfuric acid, sulfurous acid, perchloric acid, tetrafluoroboric acid, hexafluorophosphate, acetic acid, citric acid, malic acid, tartaric acid, maleic acid, oxalic acid, succinic acid, adipic acid, and linolenic acid. In some specific embodiments, n is 1, and HY is hydrochloric acid.

[0016] Another aspect of this application provides a method for preparing the above-mentioned compound of formula I or a pharmaceutically acceptable salt thereof, comprising reacting the compound of formula II with a hydrazine compound to obtain the compound of formula I or a pharmaceutically acceptable salt thereof:

[0017] In some embodiments, the hydrazine compound is hydrazine or hydrated hydrazine, preferably hydrated hydrazine.

[0018] In some embodiments, the molar ratio of the compound of formula II to the hydrazine compound in the preparation method is 1:1 to 1:10, preferably 1:1 to 1:5, 1:1 to 1:3, more preferably 1:1 to 1:2.5, 1:1 to 1:2.2, or 1:1 to 1:1.5.

[0019] In some specific embodiments, the molar ratio of the compound of formula II to hydrazine hydrate is 1:1 to 1:3; preferably 1:1 to 1:2.5, 1:1 to 1:1.5, and more preferably 1:1 to 1:2.2, 1:1.2.

[0020] In some embodiments, the mass ratio of the compound of formula II to the hydrazine compound (e.g., hydrazine hydrate) in the preparation method is 1:1 to 10:1, preferably 1:1 to 5:1, for example 1.5:1 to 3.5:1.

[0021] In some embodiments, the reaction is carried out in the presence of solvent A.

[0022] In some specific embodiments, solvent A is selected from one or more of tetrahydrofuran, methyltetrahydrofuran, acetonitrile, dichloromethane, 1,2-dichloroethane, acetone, ethyl acetate, isopropyl acetate, butyl acetate, toluene, N,N-dimethylformamide, methyl tert-butyl ether, chloroform, and water; preferably, solvent A is acetonitrile or dichloromethane.

[0023] In some specific embodiments, the mass ratio of the compound of formula II to the solvent A is 1:1 to 1:20, 1:1.5 to 1:5, 1:1.5 to 1:4, or 1:5 to 1:20.

[0024] In some embodiments, the reaction is carried out without the use of a base or in the presence of a base.

[0025] In some specific embodiments, the reaction is carried out in the presence of a base, which is selected from potassium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, triethylamine, DIPEA, DBU, and tetramethylguanidine; preferably, the base is DBU.

[0026] In some specific embodiments, the reaction is carried out under alkaline conditions, and the molar ratio of the compound of formula II to the base is 1.0:0 to 1.0:1.0, preferably 1.0:0.1 to 1.0:0.5, and more preferably 1.0:0.1.

[0027] In some embodiments, the reaction temperature is 0-100°C, preferably 10-80°C or 10-40°C.

[0028] In some embodiments, the reaction time is 1-20 hours, for example 2-10 hours, 3-9 hours, or 4-8 hours.

[0029] In some embodiments, the preparation method of the compound of formula I or a pharmaceutically acceptable salt thereof further includes: post-reaction extraction, washing, drying, and concentration.

[0030] In some embodiments, the preparation method of the compound of formula I or a pharmaceutically acceptable salt thereof is as follows:

[0031] 20.0 g of compound II and 4.81 g of 80% hydrazine hydrate were added sequentially to 50 mL of acetonitrile. 1.52 g of DBU was then added and the mixture was stirred at 20-30 °C for 6 h. The reaction solution was poured into dichloromethane, water was added, and the mixture was stirred and allowed to stand before separation. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated to obtain compound I.

[0032] This application also provides a method for preparing iruxitinib from a compound of formula I or a pharmaceutically acceptable salt thereof, comprising reacting a compound of formula I or a salt thereof with a compound of formula IIIa (e.g., formula IIIa-1) or a compound of formula IIIb to obtain iruxitinib:

[0033] in,

[0034] X - It counteracts anions;

[0035] R1, R2, R3, and R4 are each independently selected from C1 to C4 alkyl groups (e.g., C1 to C3 alkyl, C1 to C2 alkyl, methyl, ethyl, propyl, or butyl).

[0036] In some embodiments, the method for preparing iruxitinib comprises reacting a compound of formula I or a pharmaceutically acceptable salt thereof with a compound of formula IIIa-1 to obtain iruxitinib:

[0037] Among them, X - It counteracts anions.

[0038] In some embodiments, the method for preparing iruxitinib includes:

[0039] In some implementations, X - Selected from Cl - ,Br - I - BF 4- PF 6- AsF 6- 、SbF 6- and ClO 4- X - Cl is preferred - .

[0040] In some embodiments, the compound of formula IIIa is:

[0041] In some embodiments, the compound of formula IIIb is:

[0042] In some embodiments, the molar ratio of the compound of formula IIIa (e.g., formula IIIa-1, formula IIIa-2) or formula IIIb (e.g., formula IIIb-1) to the compound of formula I is 1.0:1.0 to 1.0:3.0, preferably 1.0:1.0 to 1.0:1.5, more preferably 1.0:1.0 to 1.0:1.4, for example 1.0:1.0, 1.0:1.3.

[0043] In some embodiments, the reaction is carried out in the presence of solvent B.

[0044] In some embodiments, the solvent B is selected from one or more of tetrahydrofuran, methyltetrahydrofuran, methanol, ethanol, isopropanol, acetonitrile, dichloromethane, 1,2-dichloroethane, acetone, ethyl acetate, isopropyl acetate, butyl acetate, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, chloroform, and water, wherein the solvent B is preferably ethanol.

[0045] In some embodiments, the weight ratio of solvent B to the compound of formula IIIa (e.g., formula IIIa-1, formula IIIa-2) or formula IIIb (e.g., formula IIIb-1) is 3.0:1.0 to 20.0:1.0, 4.0:1.0 to 20.0:1.0, preferably 3.0:1.0 to 8.0:1.0, 4.0:1.0 to 8.0:1.0, more preferably 3.0:1.0 to 6.0:1.0, 3.0:1.0 to 5.5:1.0, 5.0:1.0.

[0046] In some embodiments, the reaction temperature is 10–80°C, preferably 10–30°C;

[0047] In some embodiments, the reaction time is 5-20 hours, for example 10-20 hours or 15-20 hours.

[0048] In some specific embodiments, the preparation method of the ibruxitinib is as follows:

[0049] 20.0 g of compound I (1.3 eq) was dissolved in ethanol, 18.69 g of compound III was added, and the mixture was stirred at room temperature for 16 h. Then, n-heptane was added, and the mixture was stirred at room temperature for another 1 h. The mixture was filtered and dried to obtain iruxitinib.

[0050] In some embodiments, the method for preparing iruxitinib further includes: a method for preparing a compound of formula I or a salt thereof.

[0051] In some embodiments, the method for preparing iruxitinib further includes: reacting the compound of formula IV in an organic solvent C with a Vilsmeier reagent formed by a chlorinating agent and an amide reagent to obtain a compound of formula IIIa (e.g., formula IIIa-1) or formula IIIb.

[0052] In some embodiments, the method for preparing iruxitinib includes:

[0053] Step 1: Compound IV is reacted with Vilsmeier's reagent, formed by a chlorinating agent and an amide reagent, in organic solvent C to give compound IIIa;

[0054] Step 2: The compound of formula IIIa reacts with the compound of formula I in solvent B to obtain iruxitinib;

[0055] In some embodiments, the method for preparing iruxitinib further includes:

[0056] Compound IV reacts with Vilsmeier's reagent, formed by a chlorinating agent and DMF, in organic solvent C to give compound IIIa-1;

[0057] In some embodiments, the method for preparing iruxitinib includes:

[0058] Step 1: Compound IV is reacted with Vilsmeier's reagent, formed by chlorinating agent and DMF, in organic solvent C to give compound IIIa-1;

[0059] Step 2: The compound of formula IIIa-1 is reacted with the compound of formula I in solvent B to obtain iruxitinib;

[0060] In some embodiments, the method for preparing iruxitinib further includes:

[0061] Compound IV reacts with Vilsmeier's reagent, formed by a chlorinating agent and an amide reagent, in organic solvent C to give compound IIIb.

[0062] In some embodiments, the method for preparing iruxitinib includes:

[0063] Step 1: Compound IV is reacted with Vilsmeier's reagent, formed by a chlorinating agent and an amide reagent, in organic solvent C to give compound IIIb;

[0064] Step 2: The compound of formula IIIb reacts with the compound of formula I in solvent B to obtain iruxitinib;

[0065] In some embodiments, the organic solvent C is selected from one or more of dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, acetonitrile, ethyl acetate, tetrahydrofuran, methyltetrahydrofuran, and DMF, preferably acetonitrile or methyltetrahydrofuran.

[0066] In some embodiments, the chlorinating agent is selected from one or more of phosphorus oxychloride, phosphorus pentachloride, thionyl chloride, thiocyanate, oxalyl chloride, and triphosgene, preferably oxalyl chloride.

[0067] In some embodiments, the amide reagent is selected from one or more of N,N-dimethylformamide, N,N-diethylformamide, N,N-dipropylformamide, and N,N-dibutylformamide, preferably N,N-dimethylformamide or N,N-diethylformamide.

[0068] In some embodiments, the molar ratio of the compound of formula IV to the chlorinating agent is 1:1.0 to 1:3.0; preferably 1:1.2 to 1:3.0, 1:1.2 to 1:2.0, more preferably 1:1.5 to 1:2.6, for example 1:1.5.

[0069] In some implementations, the reaction time for step 1 is 1-10 hours, for example, 2-3 hours.

[0070] In some embodiments, the molar ratio of the compound of formula IV to the amide reagent is 1:1.0 to 15.0; preferably, or more preferably, the molar ratio of the compound of formula IV to the amide reagent is 1:3.0 to 1:15.0, or 1:10.0 to 1:15.0; more preferably, the molar ratio of the compound of formula IV to the amide reagent is 1:3 to 1:13, 1:3.5, 1:12.9, or 1:12.5.

[0071] In some embodiments, the reaction temperature of step 1 is 0–120°C; preferably, the reaction temperature of step 1 is 60–100°C.

[0072] In some specific embodiments, the preparation method of the ibruxitinib is as follows:

[0073] Step 1: Cool a solution of 20.97 g oxalyl chloride in 65 mL acetonitrile to 0–5 °C, add 70.81 g DMF dropwise, and then bring the temperature back to room temperature. Add 10.0 g of compound IV to the above reaction system, heat to 85–90 °C, and stir for 2 h. Add tetrahydrofuran, filter, and dry to obtain compound III.

[0074] Step 2: Dissolve 20.0 g of compound I (1.3 eq) in ethanol, add 18.69 g of compound III, stir at room temperature for 16 h, add n-heptane, continue stirring at room temperature for 1 h, filter, and dry to obtain ibruxitinib.

[0075] In another aspect, this application provides a crystal form of iruxitinib, whose X-ray powder diffraction pattern (measured using Cu Kα radiation) has three, four, or five characteristic peaks at 2θ angles of 4.0±0.2°, 7.8±0.2°, 11.6±0.2°, 15.5±0.2°, and 19.4±0.2°.

[0076] In some embodiments, the X-ray powder diffraction pattern of the crystal form has characteristic peaks at 2θ angles of 4.0±0.2°, 7.8±0.2°, and 11.6±0.2°. In some embodiments, the X-ray powder diffraction pattern of the crystal form has characteristic peaks at 2θ angles of 4.0±0.2°, 7.8±0.2°, 11.6±0.2°, 15.3±0.2°, 15.5±0.2°, and 19.4±0.2°. In some embodiments, the X-ray powder diffraction pattern of the crystal form has characteristic peaks at 2θ angles of 4.0±0.2°, 7.8±0.2°, 11.6±0.2°, 15.3±0.2°, 15.5±0.2°, 19.2±0.2°, and 19.4±0.2°.

[0077] In some embodiments, the X-ray powder diffraction pattern of the crystal form also has characteristic peaks at one or more of the following 2θ angles: 15.3±0.2°, 19.2±0.2°, 21.3±0.2°, 23.1±0.2°, and 23.2±0.2°.

[0078] In some embodiments, the X-ray powder diffraction pattern of the crystal form is essentially as shown in Figure 3.

[0079] In some embodiments, the peak positions and relative intensities of the X-ray powder diffraction patterns of the crystal form are shown in Table 1:

[0080] Table 1: XRPD data for crystal forms

[0081] In some embodiments, the TGA pattern of the crystal form is basically as shown in Figure 4.

[0082] In some embodiments, the DSC spectrum of the crystal form has an endothermic peak at 217.54±2℃.

[0083] In some embodiments, the DSC spectrum of the crystal form is essentially as shown in Figure 5.

[0084] This application also provides a pharmaceutical composition comprising the crystal form of iruxitinib and pharmaceutically acceptable excipients.

[0085] In some embodiments, the crystalline form of iruxitinib or a pharmaceutical composition thereof may be administered to a subject in need at a therapeutically effective amount, for example by any route known in the art, including oral, parenteral, subcutaneous, intramuscular, intraperitoneal, or intranasal administration. The therapeutically effective amount may be determined by a person skilled in the art based on the subject's health status, weight, age, sex, disease severity, etc.

[0086] The beneficial effects achieved by this application are:

[0087] 1. The iruxitinib key intermediate compound I provided in this application can be obtained by a one-step reaction from the inexpensive and readily available compound II. The reaction is mild, the process is simple, the yield can be as high as 95% or more, and the product purity can reach 99% or more (no purification is required and it can be used directly for subsequent reactions).

[0088] 2. The synthetic route for preparing iruxitinib using the key intermediate compound of formula I provided in this application is short, with only two reaction steps starting from compound II, and the process is simple to operate;

[0089] 3. The iruxitinib preparation process provided in this application has the following advantages compared with the prior art: the synthetic route is short, the reaction conditions are mild, there is less waste, the atom economy is high, the process is simple, the yield is high, the total yield of the two-step reaction can reach more than 75%, especially more than 80%, and the product quality is excellent (the purity of iruxitinib can reach more than 99%). It avoids the use of expensive metal reagents and the introduction of unnecessary protecting groups in the prior art, and is suitable for industrial scale-up production, achieving unexpected technical effects.

[0090] In summary, the iruxitinib preparation process provided in this application is based on green chemistry principles, adopts a convergent route, has good safety, produces less waste, has high atom economy, avoids the use of expensive metal reagents and the introduction of unnecessary protecting groups in existing technologies, has a simple process, high yield, excellent quality, and significantly lower cost than existing technologies, thus having extremely high social and economic value. Attached Figure Description

[0091] Figure 1 shows the compound of formula I in Example 3 of this application. 1 H-NMR spectrum.

[0092] Figure 2 shows the ibruxitinib crystals in Example 7 of this application. 1 H-NMR spectrum.

[0093] Figure 3 shows the XRD pattern of crystal form A of ibruxitinib in this application.

[0094] Figure 4 shows the TGA spectrum of crystal form A of ibruxitinib in this application.

[0095] Figure 5 shows the DSC spectrum of crystal form A of ibruxitinib in this application.

[0096] Figure 6 shows the XRD patterns of ibruxitinib crystal form A of this application after being stored at 25℃ / RH60% for 3 months and 6 months.

[0097] Figure 7 shows the XRD patterns of ibruxitinib crystal form A of this application after 3 months and 6 months of accelerated stability under 40℃ / RH75%. Detailed Implementation

[0098] The present application will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described are only some of the preferred embodiments for implementing the present application, and not all of the embodiments. They are not intended to limit the present application. Any equivalent substitutions made in the art based on the disclosure of the present application shall fall within the protection scope of the present application.

[0099] Nuclear magnetic resonance (NMR) 1 H-NMR shift (δ) is given in parts per million (ppm); nuclear magnetic resonance (NMR) 1 H-NMR measurements were performed using a Bruker AVANCE-400 NMR spectrometer. The solvent was deuterated dimethyl sulfoxide (DMSO-d6), and the internal standard was tetramethylsilane (TMS). Chemical shifts were expressed as 10⁻⁶ ppm. -6 (ppm) is given as the unit.

[0100] The term "room temperature" as used in this application refers to a temperature of 10–25°C.

[0101] In this application, the terms “comprising,” “including,” and “containing,” and their equivalents, shall be understood in an open, non-exclusive sense, meaning “including but not limited to,” implying that in addition to the listed elements, components, and steps, other unspecified elements, components, and steps may also be included.

[0102] The term “independently” means that when a plurality of substituents are selected from many possible groups, the groups corresponding to these substituents may be the same or different.

[0103] Unless otherwise stated, all figures used herein to represent amounts of components, measurements, or reaction conditions should be understood to be modified by the term "about" in all cases. When used with percentages, the term "about" may mean, for example, ±1%, preferably ±0.5%, more preferably ±0.1%.

[0104] Unless the context clearly indicates otherwise, singular terms in this article cover the plural referents, and vice versa.

[0105] In this application, unless otherwise stated, percentages are weight percentages.

[0106] In this application, the drugs or reagents involved may be derived from commercial sources.

[0107] XRD: X-ray powder diffraction

[0108] The X-ray powder diffraction (XRD) measurements described in this application were performed using a Malvern-Panaco Empyrean X-ray powder diffractometer, and the specific parameters are shown in the table below:

[0109] Table 1

[0110] In this article, "the X-ray powder diffraction pattern is basically the same as that in Figure 3" means that the X-ray powder diffraction pattern is basically the same as that in Figure 3. The term "basically the same" in X-ray powder diffraction pattern means that the representative peak positions and intensity variations are taken into account.

[0111] TGA: Thermogravimetric Analysis

[0112] The thermogravimetric analysis (TGA) described in this application was performed using a METTLER TOLEDO TGA-2 instrument with a heating rate of 10℃ / min and a temperature range of 30-300℃. The nitrogen purging rate during the test was 20mL / min.

[0113] The error of TGA can be within approximately ±0.5% of mass. In this article, "the TGA spectrum is basically as shown in Figure 4" means that the TGA spectrum is basically the same as Figure 4. The term "basically the same" for the TGA spectrum means that this error variation is taken into account.

[0114] DSC: Differential Scanning Calorimetry

[0115] The differential scanning calorimetry (DSC) measurement described in this application was performed using a METTLER TOLEDO DSC-1, with a heating rate of 10℃ / min and a temperature range of 25-250℃. The nitrogen purging rate during the test was 60mL / min.

[0116] In this article, "the DSC spectrum is basically the same as that in Figure 5" means that the DSC spectrum is basically the same as that in Figure 5. The term "basically the same" in DSC spectrum means that the representative characteristic peak positions will be taken into account.

[0117] Abbreviations used in this article:

[0118] In this article, crystal form II is crystal form II prepared according to the method disclosed in WO2020219524A1.

[0119] Example

[0120] The technical solution of this application will be further described in detail below through embodiments, but the scope of protection of this application is not limited to these embodiments.

[0121] Example 1: Preparation of Compound I

[0122] 100 g (0.50 mol) of compound II and 37.5 g (0.6 mol, 1.2 eq) of 80% hydrazine hydrate were added sequentially to 250 mL of acetonitrile. 7.61 g (0.05 mol, 0.1 eq) of DBU was added with stirring, and the mixture was stirred at 20-30 °C for 6 h. The reaction mixture was poured into 500 mL of dichloromethane, and 250 mL of water was added. The mixture was stirred, allowed to stand, and separated. The aqueous phase was extracted twice with dichloromethane (100 mL × 2). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure at 35-40 °C to obtain 112.84 g of compound I, with a yield of 98.0%. No further purification was required; it was directly used in the next reaction.

[0123] Example 2: Preparation of Compound I

[0124] 100 g (0.50 mol) of compound II and 37.5 g (0.6 mol, 1.2 eq) of 80% hydrazine hydrate were added sequentially to 250 mL of acetonitrile and stirred at 20–30 °C for 6 h. The reaction mixture was poured into 500 mL of dichloromethane, 250 mL of water was added, the mixture was stirred, allowed to stand, and separated. The aqueous phase was extracted twice with dichloromethane (100 mL × 2). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure at 35–40 °C to obtain 104.78 g of compound I, with a yield of 91.0%. No further purification was required, and the compound was used directly in the next reaction.

[0125] Example 3: Preparation of Compound I

[0126] 100.0 g (0.50 mol) of compound II and 63.1 g (1.0 mol, 2.0 eq) of 80% hydrazine hydrate were sequentially added to 300 mL of dichloromethane and stirred at 30–40 °C for 4 h. The reaction mixture was poured into 200 mL of dichloromethane, 200 mL of water was added, the mixture was stirred, allowed to stand, and separated. The aqueous phase was extracted twice more with dichloromethane (200 mL × 2). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure at 35–40 °C to obtain 110.2 g of compound I, with a yield of 94.8% and a purity of 99.25%. No further purification was required; it was directly used in the next reaction. LCMS C8H 14 N4O2S(M+H) + Calculated value: m / z = 231.08; Measured value: 231.1.

[0127] Example 4: Preparation of Compound IIIa-2

[0128] 20.97 g of oxalyl chloride (165.22 mmol, 2.2 eq) was added to 65 mL of acetonitrile, stirred, and cooled to 0–5 °C in an ice bath. Then, 70.81 g of DMF (968.79 mmol, 12.9 eq) was added dropwise, with the temperature controlled below 10 °C during the addition. The ice bath was removed, and the reaction mixture was gradually brought to room temperature. 10.0 g of compound IV (75.1 mmol) was added to the mixture, and the mixture was stirred for 5–10 min. The temperature was then raised to 85–90 °C and stirred for 2 h. After the reaction was complete, the mixture was cooled to room temperature, and 100 mL of tetrahydrofuran was added. The mixture was stirred for 2 h, then cooled to 0–5 °C and stirred for another 2 h. The mixture was filtered, washed with a mixed solvent of 100 mL THF and 100 mL MTBE, and dried under vacuum to constant weight to give 19.45 g of compound III, in 92.6% yield.

[0129] Example 5: Preparation of Compound IIIb-1

[0130] 238.3 g of oxaloyl chloride (1877.6 mmol, 2.5 eq) was added to 600 mL of methyltetrahydrofuran, stirred, and cooled to 0–5 °C in an ice bath. Then, 265.9 g of N,N-diethylformamide (2628.6 mmol, 3.5 eq) was added dropwise, with the temperature controlled below 10 °C during the addition. The ice bath was removed, and the reaction mixture was gradually brought to room temperature. 100.0 g of compound IV (751.0 mmol) was added to the mixture, and the mixture was stirred for 5–10 min. The temperature was then raised to 80–90 °C and stirred for 2 h. After the reaction was complete, the mixture was cooled to room temperature, and 600 mL of n-heptane was added. The mixture was stirred for 2 h, then cooled to 0–5 °C and stirred for another 2 h. The mixture was filtered, washed with 200 mL of n-heptane, and dried under vacuum to constant weight to give 265.1 g of compound III, in 94.8% yield. LCMS free base (M+H) + Calculated value: m / z = 300.22; Measured value: 300.2.

[0131] Example 6: Preparation of Iruxitinib

[0132] 20.0 g of compound I (86.85 mmol, 1.3 eq) was dissolved in 100 g of ethanol, and 18.69 g of compound IIIa-2 (66.8 mmol, 1.0 eq) was added. The mixture was stirred at room temperature for 16 h. After the reaction was complete, n-heptane was added, and the mixture was stirred at room temperature for another 1 h. The mixture was filtered, the filter cake was washed with n-heptane, and dried under reduced pressure to give 21.77 g of ibruxitinib, with a yield of 85% and a purity of over 99.5%.

[0133] Example 7: Preparation of iruxitinib crystal form

[0134] 20.0 g of compound I (86.8 mmol, 1.0 eq) was dissolved in 100 g of ethanol, and 32.33 g of compound IIIb-1 (86.8 mmol, 1.0 eq) was added. The mixture was stirred at 20–30 °C for 20 h. After the reaction was complete, n-heptane was added, and the mixture was stirred at room temperature for another 1 h. The mixture was filtered, and the filter cake was washed with n-heptane and dried under reduced pressure to obtain 27.9 g of ibruxitinib crystals, designated as crystal form A, with a yield of 84% and a purity of 99.43%. LCMS C 17 H 17 N4O2S(M+H) + Calculated value: m / z = 384.12; Measured value: 384.2. The X-ray powder diffraction pattern, TGA pattern, and DSC pattern of the crystal are shown in Figures 3, 4, and 5, respectively.

[0135] Example 8: Preparation of the hydrochloride salt of compound I

[0136] 2.0 g of compound I (8.68 mmol) was dissolved in 10 mL of ethyl acetate and the mixture was kept at 0–5 °C. 50 mL of a 4 mol / L ethyl hydrochloride solution was added. The mixture was stirred at 0–5 °C for 4 h. After the reaction was complete, the mixture was filtered, the filter cake was washed with ethyl acetate, and dried under reduced pressure to obtain 2.1 g of compound I hydrochloride, with a yield of 91%.

[0137] Example 9: Preparation of Iruxitinib

[0138] 20.0 g of compound I hydrochloride (75.0 mmol, 1.0 eq) was dissolved in 100 g of ethanol, and 27.9 g of compound IIIb-1 (75.0 mmol, 1.0 eq) was added. The mixture was stirred at 20–30 °C for 20 h. After the reaction was complete, n-heptane was added, and the mixture was stirred at room temperature for another 1 h. The mixture was filtered, and the filter cake was washed with n-heptane. The filter cake was dispersed in 100 mL of ethyl acetate, and 100 mL of saturated sodium carbonate solution was added. The mixture was stirred until dissolved, allowed to stand, and separated. The aqueous phase was extracted once with 100 mL of ethyl acetate. The organic phases were combined and concentrated under reduced pressure at 45 °C and ≤-0.08 MPa. 200 mL of anhydrous ethanol was added to disperse the mixture, and the mixture was filtered. The filter cake was washed with anhydrous ethanol and dried under reduced pressure to obtain 27.6 g of ibruxitinib, with a yield of 83%. LCMS C 17 H 17 N7O2S(M+H) + Calculated value: m / z = 384.12; Measured value: 384.2.

[0139] Example 1: Stability Study of Iruxitinib Crystal Form A

[0140] To investigate the storage stability of iruxitinib crystal form A prepared in Example 7 of this application, the sample was placed under accelerated stability conditions of 25℃ / RH60% and 40℃ / RH75% for 3 months and 6 months respectively to examine its crystal form stability. The results are shown in Table 1 below, and the XRD patterns are shown in Figures 6 and 7 respectively.

[0141] Table 1. Stability test of exemplary iruxitinib crystal form A in this application.

[0142] As can be seen from Table 1 and Figures 6 and 7, the crystal form of ibruxitinib A did not change under the investigated conditions, indicating good stability and ensuring stable and controllable quality during drug formulation and storage.

[0143] Example 2: Hygroscopicity test of ibruxitinib crystal form A and WO2020219524A1 crystal form II

[0144] The hygroscopicity of iruxitinib crystal form A and crystal form II prepared in Example 7 was investigated by DVS experiment, and the results are shown in Table 3 below:

[0145] Table 2. Hygroscopicity test of exemplary iruxitinib crystal forms A and II of this application.

[0146] Experimental results show that, under 98% relative humidity conditions, crystal form A exhibits hygroscopic properties comparable to crystal form II, which is beneficial for the preparation and storage of pharmaceutical formulations.

[0147] Example 3: Solubility study of ibruxitinib crystal form A and WO2020219524A1 crystal form II

[0148] In accordance with the current guidelines for solubility testing in the Chinese Pharmacopoeia, an experiment was designed to test the solubility of crystal form A and crystal form II in different solvent media.

[0149] Table 3. Solubility experiments of exemplary iruxitinib crystal forms A and II in this application.

[0150] The experimental results show that crystal form A and crystal form II have comparable solubility characteristics, meeting the solubility requirements of the active pharmaceutical ingredient and the formulation.

[0151] Example 4: Pharmacokinetic studies of ibruxitinib crystal form A and WO2020219524A1 crystal form II

[0152] Animal experiments were conducted using ibruxitinib crystal forms A and II, respectively. The test drug was accurately weighed and mixed with 0.5% methylcellulose solution to prepare a 0.5 mg / mL suspension for oral administration. Rats (n=2, half male and half female) were given a single oral dose of 1 mg / kg of the test drug. Whole blood was collected before administration and at 0.083, 0.25, 0.5, 1, 2, 4, 8, and 24 hours after administration. Plasma was obtained after centrifugation. The concentration of the drug in rat plasma samples was quantitatively determined using LC-MS / MS, and pharmacokinetic parameters were calculated using a non-compartmental model with WinNonlin software.

[0153] The results showed that crystal form A exhibited pharmacokinetic properties consistent with pharmaceutical expectations, including AUC and C. max wait.

[0154] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. For purposes of description and disclosure, all patents, patent applications, and other publications are expressly incorporated herein by reference. These publications are provided solely because their publications predate the filing date of this application. All statements regarding the dates of these documents or representations of their contents are based on information available to the applicant and do not constitute any acknowledgment of the accuracy of the dates or contents of these documents. Furthermore, in any country, any reference to these publications herein does not constitute an endorsement that such publications are part of the general knowledge in the art.

[0155] Those skilled in the art will recognize that the scope of this application is not limited to the various specific implementations and embodiments described above, but rather that various modifications, substitutions, or recombinations can be made without departing from the spirit of this application, all of which fall within the protection scope of this application.

Claims

1. A compound of formula I or a pharmaceutically acceptable salt thereof:

2. The compound according to claim 1 or a pharmaceutically acceptable salt thereof, wherein, The pharmaceutically acceptable salt is a compound represented by formula Ia; Where HY is acid, and n is any value from 0 to 4.

3. The compound according to claim 2 or a pharmaceutically acceptable salt thereof, wherein, The HY is selected from one of the following: hydrochloric acid, hydrobromic acid, nitric acid, phosphoric acid, metaphosphoric acid, sulfuric acid, sulfurous acid, perchloric acid, tetrafluoroboric acid, hexafluorophosphoric acid, acetic acid, citric acid, malic acid, tartaric acid, maleic acid, oxalic acid, succinic acid, adipic acid, and linolenic acid.

4. A method for preparing a compound of formula I or a pharmaceutically acceptable salt thereof according to any one of claims 1-3, comprising reacting a compound of formula II with a hydrazine compound to obtain the compound of formula I or a pharmaceutically acceptable salt thereof:

5. The method according to claim 4, wherein, The hydrazine compound is hydrazine or hydrated hydrazine.

6. The method according to claim 4 or 5, wherein, The molar ratio of the compound of formula II to the hydrazine compound is 1:1 to 1:10, 1:1 to 1:5, 1:1 to 1:3, 1:1 to 1:2.5, 1:1 to 1:2.2 or 1:1 to 1:1.

5.

7. The method according to any one of claims 4-6, wherein, The reaction is carried out in the presence of solvent A, which is selected from one or more of tetrahydrofuran, methyltetrahydrofuran, acetonitrile, dichloromethane, 1,2-dichloroethane, acetone, ethyl acetate, isopropyl acetate, butyl acetate, toluene, N,N-dimethylformamide, methyl tert-butyl ether, chloroform, and water; and / or The mass ratio of the compound of formula II to solvent A is 1:1 to 1:20, 1:1.5 to 1:5, or 1:5 to 1:20; and / or The reaction temperature is 0-100℃; and / or The reaction time is 1-20 hours.

8. The method according to claim 4, wherein, The reaction is carried out without the use of a base or under alkaline conditions; Preferably, the reaction is carried out in the presence of a base, wherein the base is selected from potassium carbonate, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, triethylamine, DIPEA, DBU and tetramethylguanidine; Preferably, the molar ratio of the compound of formula II to the base is 1.0:0 to 1.0:1.0, or 1.0:0.1 to 1.0:0.5, or 1.0:0.

1.

9. A method for preparing iruxitinib, comprising reacting a compound of formula I or a pharmaceutically acceptable salt thereof according to any one of claims 1-3 with a compound of formula IIIa or a compound of formula IIIb to obtain iruxitinib; in, X - It counteracts anions, with X being the preferred choice. - Selected from Cl - ,Br - I - BF 4- PF 6- AsF 6- 、SbF 6- and ClO 4- ; R1, R2, R3, and R4 are each independently selected from C1 to C4 alkyl groups.

10. The method according to claim 9, wherein, The compound of formula IIIa is or The compound of formula IIIb is 11. The method according to claim 9 or 10, wherein, The molar ratio of the compound of formula IIIa or IIIb to the compound of formula I is 1.0:1.0 to 1.0:3.0, 1.0:1.0 to 1.0:1.5, or 1.0:1.0 to 1.0:1.4; and / or The reaction is carried out in the presence of solvent B, which is selected from one or more of tetrahydrofuran, methyltetrahydrofuran, methanol, ethanol, isopropanol, acetonitrile, dichloromethane, 1,2-dichloroethane, acetone, ethyl acetate, isopropyl acetate, butyl acetate, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, chloroform, and water; and / or The weight ratio of solvent B to the compound of formula III is 3.0:1.0 to 20.0:1.0, 4.0:1.0 to 20.0:1.0, 3.0:1.0 to 8.0:1.0, or 4.0:1.0 to 8.0:1.0; and / or The reaction temperature is 10–80°C; and / or The reaction time is 5 to 20 hours.

12. A crystal form of iruxitinib, wherein, The X-ray powder diffraction pattern of the crystal form has 3, 4 or 5 characteristic peaks at 2θ angles of 4.0±0.2°, 7.8±0.2°, 11.6±0.2°, 15.5±0.2° and 19.4±0.2°.

13. The crystal form according to claim 12, wherein, The X-ray powder diffraction pattern of the crystal form has characteristic peaks at 2θ angles of 4.0±0.2°, 7.8±0.2°, 11.6±0.2°, 15.3±0.2°, 15.5±0.2° and 19.4±0.2°; The X-ray powder diffraction pattern of the crystal form also has characteristic peaks at one or more of the following 2θ angles: 19.2±0.2°, 21.3±0.2°, 23.1±0.2°, and 23.2±0.2°. Preferably, the X-ray powder diffraction pattern of the crystal form is basically as shown in Figure 3.

14. The crystal form according to claim 12 or 13, wherein, The TGA spectrum of the crystal form is basically shown in Figure 4; The DSC spectrum of the crystal form shows an endothermic peak at 217.54±2℃; or The DSC spectrum of the crystal form is basically shown in Figure 5.

15. A pharmaceutical composition comprising the crystal form of iruxitinib as described in any one of claims 12-14 and pharmaceutically acceptable excipients.

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