WO2024012568A1

WO2024012568A1 - A key intermediate for preparing glucopyranosyl derivatives and preparation method thereof

Info

Publication number: WO2024012568A1
Application number: PCT/CN2023/107451
Authority: WO
Inventors: Sai RUAN; Fei Peng; Weihui YUAN; Zheng Li; Zongyuan ZHANG; Wuyong WU; Junxu LIAO; Zheng Gu
Original assignee: Sunshine Lake Pharma Co., Ltd.
Priority date: 2022-07-15
Filing date: 2023-07-14
Publication date: 2024-01-18
Also published as: CN117430571A

Abstract

The invention relates to a key intermediate for preparing glucopyranosyl derivatives and preparation method thereof, the glucopyranosyl derivatives are sodium-dependent glucose transporter (SGLT) inhibitors. Specifically, the key intermediate has stable properties, less impurities, and high optical purity (diastereoselectivity); the reagents used in the preparation method are cheap, the reaction conditions are mild, and there is no need to use silica gel column chromatography for purification and the post-treatment is simple, the purification is easy, the equipment requirements are low, the production cost is low, and the process is safer and more controllable, and suitable for industrial production.

Description

A KEY INTERMEDIATE FOR PREPARING GLUCOPYRANOSYL DERIVATIVES AND PREPARATION METHOD THEREOF

FIELD OF THE INVENTION

The invention belongs to the field of medicinal chemistry, and specifically relates to a key intermediate for preparing glucopyranosyl derivatives and preparation method thereof. The glucopyranosyl derivatives are sodium-dependent glucose transporter (SGLT) inhibitors.

BACKGROUND OF THE INVENTION

It has been found by research that glucose transporter proteins are a class of carrier proteins embedded in the cell membrane for transporting glucose. Glucose must be relied on glucose transporter protein to cross lipid bilayer structure of cell membranes. Glucose transporter proteins are divided into two categories. The first category is sodium-dependent glucose transporters (SGLTs) , and the other category is glucose transporters (GLUTs) . Two major family members of SGLTs are SGLT-1 and SGLT-2. SGLT-1 is mainly distributed in small intestine, kidney, heart and windpipe, predominantly expressed in the brush border of the small intestine and the S3 segment of the renal proximal tubule, and a few expressed in heart and windpipe, and transports glucose and galactose with a sodium to glucose ratio of 2: 1. While SGLT-2 is mainly distributed in kidney, predominantly expressed in the S1 and S2 segments of the renal proximal tubule, and transports glucose with a sodium to glucose ratio of 1: 1. In biological bodies, glucose is transported by SGLTs through active transport against a concentration gradient with simultaneous energy consumption. While glucose is transported by GLUTs through facilitated diffusion along a concentration gradient without energy consumption in the transport process. Research indicates that normally plasma glucose is filtered in the kidney glomeruli in which 90%of glucose in the early S1 and S2 segments of the renal tubule is actively transported to epithelial cells by SGLT-2 and 10%of glucose in the distal S3 segment of the renal tubule is actively transported to epithelial cells by SGLT-1, and then transported to peripheral capillary network by GLUT of epithelial basement membrane, accomplishing reabsorption of glucose by renal tubules. Hence, SGLTs is the first stage in regulation of glucose metabolism in cells, and an ideal target for treating diabetes effectively. It has been found by research that the patients with SGLT-2 impairment would excrete large amounts of urine glucose. This provides the factual basis of treating diabetes by reducing glucose uptake through inhibiting SGLT-2 activity. Therefore, inhibiting activity of SGLTs transport protein could block reabsorption of glucose in renal tubules and increase excretion of glucose in urine to normalize the plasma glucose concentration and further control the diabetes and diabetic complications. Inhibiting SGLTs would not influence the normal anti-regulatory mechanism of glucose, which may cause the risk of hypoglycemia. Meanwhile, lowering blood glucose through an increase of renal glucose excretion could promote weight loss in obese patients. It has also been found by research that the mechanism of action of SGLTs inhibitors is independent of pancreatic β cell dysfunction or the degree of insulin resistance. Therefore, the efficacy of SGLTs inhibitors will not decrease with the severe insulin resistance or β-cell failure. SGLTs inhibitors could be used alone or in combination with other hypoglycemic agents. Therefore, SGLTs inhibitors are ideal and novel hypoglycemic agents.

In addition, it has also been found by research that SGLTs inhibitors can be used for treating diabetes-related complications. Such as retinopathy, neuropathy, kidney disease, insulin resistance caused by glucose metabolic disorder, hyperinsulinemia, hyperlipidemia, obesity, and so on. Meanwhile, SGLTs inhibitors can also be used in combination with current treatment regimens, such as sulphonamides, thiazolidinedione, metformin, and insulin, etc, which can reduce the dose without impacting on the effectiveness of the medicine, and thereby avoid or reduce side effects, and improve patient compliance.

After hard research, the applicant had developed a glucopyranosyl derivative as a sodium-dependent glucose transporter (SGLT) inhibitor, and disclosed that the compound of formula (I) has good SGLTs inhibition activity in WO2015043511A1 and WO2016173425A1. The said compound is currently in clinical phase III, and is a very promising new type of diabetes treatment drug.

Subsequently, the applicant disclosed a preparation method of the compound of formula (I) in WO2020143653A1, wherein, the following reaction for preparing the intermediate is disclosed in the synthetic route: the compound of formula (X) and the Grignard reagent obtained by Grignard exchange of iodomethyl pivalate and isopropylmagnesium chloride lithium chloride undergo an addition reaction to obtain the compound of formula (IX) (refer to step 4 of Example 1 of the specification for details) .

Step a:

The applicant also disclosed a preparation method of the compound of formula (I) in WO2022007838A1, wherein, the following reaction for preparing the intermediate is disclosed in the synthetic route: the compound of formula (IXb) and the Grignard reagent obtained by Grignard exchange of iodomethyl pivalate and isopropylmagnesium chloride lithium chloride undergo an addition reaction to obtain the compound of formula (VIIIb) (refer to step 4 of Example 1 of the specification for details) .

Step b:

As can be seen from the above reactions for preparing the intermediates, the compound of formula (IXb) (the compound of formula (IXb) is identical to the compound of formula (II-a) of the present invention) and its analogous such as the compound of formula (X) can be used as starting compounds to prepare other intermediates, so as to finally obtain the compound of formula (I) . However, both step a and step b require Grignard reaction, while the Grignard reagent is expensive, the reaction conditions are harsh, the requirements for equipment are high, and the synthesis cost is high, as a result it is not suitable for industrial production.

SUMMARY

In view of the problems in the preparation of intermediates in the synthetic route of the compound of formula (I) in the prior arts, the present invention provides a key intermediate suitable for industrial production and a preparation method thereof after a large number of optimizations and explorations of the intermediates in the synthetic route of the compound of formula (I) . On one hand, the key intermediate has stable properties, less impurities, and high optical purity (diastereoselectivity) ; on the other hand, the reagents used in the preparation method are cheap, the reaction conditions are mild, and there is no need to use silica gel column chromatography for purification and the post-treatment is simple, the purification is easy, the equipment requirements are low, the production cost is low, and the process is safer and more controllable and simple.

The intermediate of the present invention has the structure of formula (I-a) , and it is an important intermediate for synthesizing the compound of formula (I) . Specifically, the present invention relates to a preparation method of the compound of formula (I-a) , the compound of formula (I-a) and crystal form A thereof.

On one hand, the present invention relates to a method for preparing the compound of formula (I-a) , comprising the following steps: the compound of formula (II-a) undergoes an addition reaction with trimethylsilylacetylene in a solvent in the presence of LiHMDS to obtain the compound of formula (I-a) ,

In some embodiments, the addition reaction is carried out in the presence of an additive, wherein the additive is 2, 4, 6-collidine, piperidine, triethylenediamine, pyrrole, tetramethylethylenediamine, tetramethyltartaramide, hexamethylphosphoric triamide, (-) -sparteine, triethylamine, propylenediamine, ethylenediamine, dimethylamine, N, N-diisopropylethylamine, 1, 8-diazabicyclo [5.4.0] undec-7-ene, 4-dimethylaminopyridine, N, N-dimethylpropenylurea, N-methylpyrrolidone or pyridine; preferably, the additive is tetramethylethylenediamine or (-) -sparteine; more preferably, the additive is tetramethylethylenediamine.

In some other embodiments, the amount of the additive is 0.2-1.2 times equivalent of the compound of formula (II-a) ; preferably, the amount of the additive is 0.5-1.0 times equivalent of the compound of formula (II-a) ; more preferably, the amount of the additive is 0.2 times, 0.5 times or 1.0 time equivalent of the compound of formula (II-a) .

In some embodiments, the amount of trimethylsilylacetylene is 1.0-2.0 times equivalent of the compound of formula (II-a) ; preferably, the amount of trimethylsilylacetylene is 1.2-1.5 times equivalent of the compound of formula (II-a) ; more preferably, the amount of trimethylsilylacetylene is 1.2 times or 1.5 times equivalent of the compound of formula (II-a) .

In some other embodiments, the amount of LiHMDS is 1.0-2.0 times equivalent of the compound of formula (II-a) ; preferably, the amount of LiHMDS is 1.2-1.5 times equivalent of the compound of formula (II-a) ; more preferably, the amount of LiHMDS is 1.2 times or 1.5 times equivalent of the compound of formula (II-a) .

In some embodiments, the solvent is tetrahydrofuran, dichloromethane, toluene, ether, 2-methyl-tetrahydrofuran, n-hexane, cyclohexane or n-heptane; preferably, the solvent is tetrahydrofuran.

In some other embodiments, in the reaction of the compound of formula (II-a) with trimethylsilylacetylene, the reaction temperature is-40℃～-80℃; preferably, the reaction temperature is-50℃～-80℃; preferably, the reaction temperature is-60℃～-80℃; more preferably, the reaction temperature is-78℃.

As described in the present invention, the method for preparing the compound of formula (I-a) is to introduce a new chiral center through an asymmetric addition reaction of trimethylsilylacetylene to the ketone group on the compound of formula (II-a) , and the compound of formula (I-a) can be obtained with high purity and high dr value through the selections and optimizations of the additives. In addition, the type and amount of the additives have different effects on the reaction. When the additive is tetramethylethylenediamine, and the amount of tetramethylethylenediamine is 0.5 times equivalent of the compound of formula (II-a) , the reactants react completely, and the product is obtained with high purity and high dr value; when the additive is (-) -Sparteine, and the amount of (-) -Sparteine is 1.0 time equivalent of the compound of formula (II-a) , the reactants react completely, and the product is obtained with high purity and high dr value.

The compound of formula (I-a) obtained by the method for preparing the compound of formula (I-a) of the present invention has high purity and high dr value, and then recrystallization can further improve the purity and dr value of the compound of formula (I-a) , wherein, the dr value can be>99: 1 after recrystallization.

The present invention also relates to tert-butyl-4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piper azine-1-carboxylate, i.e., the compound of formula (I-a) , and its crystal form. The crystal form provided by the present invention can be identified and compared with other crystals by means of characteristic X-ray single crystal diffraction pattern, X-ray powder diffraction (XRPD) pattern, differential scanning calorimetry (DSC) diagram and thermogravimetric (TGA) analysis diagram.

On one hand, the present invention provides a compound of formula (I-a) ,

On the other hand, the present invention relates to the crystal form A of the compound of formula (I-a) ,

In some embodiments, the differential scanning calorimetry of the crystal form A of the compound of formula (I-a) includes a maximum endothermic peak at 93.12℃±3℃.

In some embodiments, the crystal form A of the compound of formula (I-a) has a differential scanning calorimetry diagram substantially as shown in FIG. 1.

In some embodiments, the crystal form A of the compound of formula (I-a) has the following unit cell parameters:

Unit cell dimensions: α=90°, β=97.3928°, γ=90°;

Space group: P2₁;

Unit cell volume: and

The number of asymmetric units Z in the unit cell: 2.

In some embodiments, the X-ray powder diffraction pattern of the crystal form A of the compound of formula (I-a) has diffraction peaks at the following 2θ angles: 5.92°±0.2°, 8.62°±0.2°, 11.32°±0.2°, 12.97°±0.2°, 17.76°±0.2°, and 19.86°±0.2°.

In other embodiments, the X-ray powder diffraction pattern of the crystal form A of the compound of formula (I-a) has diffraction peaks at the following 2θ angles: 5.72°±0.2°, 5.92°±0.2°, 8.62°±0.2°, 11.32°±0.2°, 12.97°±0.2°, 13.35°±0.2°, 14.91°±0.2°, 15.29°±0.2°, 15.57°±0.2°, 16.51°±0.2°, 17.02°±0.2°, 17.76°±0.2°, 19.40°±0.2°, 19.86°±0.2°, 20.26°±0.2°, 22.52°±0.2°, and 23.82°±0.2°.

In other embodiments, the X-ray powder diffraction pattern of the crystal form A of the compound of formula (I-a) has diffraction peaks at the following 2θ angles: 5.72°±0.2°, 5.92°± 0.2°, 8.62°±0.2°, 11.32°±0.2°, 11.82°±0.2°, 12.38°±0.2°, 12.97°±0.2°, 13.35°±0.2°, 14.91°±0.2°, 15.29°±0.2°, 15.57°±0.2°, 16.51°±0.2°, 17.02°±0.2°, 17.33°±0.2°, 17.76°±0.2°, 19.40°±0.2°, 19.86°±0.2°, 20.26°±0.2°, 20.93°±0.2°, 21.59°±0.2°, 22.22°±0.2°, 22.52°±0.2°, 23.85°±0.2°, 25.21°±0.2°, 25.75°±0.2°, 26.40°±0.2°, 26.93°±0.2°, 29.84°±0.2°, 30.32°±0.2°, 32.57°±0.2°, 37.05°±0.2°, and 38.44°±0.2°.

In still other embodiments, the crystal form A of the compound of formula (I-a) has an X-ray powder diffraction pattern substantially as shown in FIG. 4.

In some embodiments, when the crystal form A of the compound of formula (I-a) is heated to 150.09℃, the weight loss is 0.1199%, and the weight loss ratio has an error tolerance of±0.1%.

In some embodiments, the crystal form A of the compound of formula (I-a) has a thermogravimetric analysis diagram substantially as shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a key intermediate of a glucopyranosyl derivative as a sodium-dependent glucose transporter (SGLT) inhibitor and preparation method thereof. Skilled in the art can learn from this article to properly improve the process parameters. Of particular note is that all similar substitutions and modifications to the skilled person is obvious, and they are deemed to be included in the present invention.

DEFINITIONS AND GENERAL TERMINOLOGY

Unless otherwise stated, terms used in the specification and claims have the following definitions.

Reference will now be made in detail to certain embodiments of the invention, examples of which are illustrated in the accompanying structures and formulas. The invention is intended to cover all alternatives, modifications, and equivalents which may be included within the scope of the present invention as defined by the claims. One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. The present invention is in no way limited to the methods and materials described herein. In the event that one or more of the incorporated literature, patents, and similar materials differs from or contradicts this application, including but not limited to defined terms, term usage, described techniques, or the like, this application controls.

It is further appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, can also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, can also be provided separately or in any suitable subcombination.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one skilled in the art to which this invention belongs. All patents and publications referred to herein are incorporated by reference in their entirety.

As used herein, the following definitions shall apply unless otherwise indicated. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, and the Handbook of Chemistry and Physics, 75th Ed. 1994. Additionally, general principles of organic chemistry are described in “Organic Chemistry” , Thomas Sorrell, University Science Books, Sausalito: 1999, and "March's Advanced Organic Chemistry” by Michael B. Smith and Jerry March, John Wiley&Sons, New York: 2007, the entire contents of which are hereby incorporated by reference.

The grammatical articles “a” , “an” and “the” , as used herein, are intended to include “at least one” or “one or more” unless otherwise indicated herein or clearly contradicted by the context. Thus, the articles are used herein to refer to one or more than one (i.e. at least one) of the grammatical objects of the article. By way of example, “a component” means one or more components, and thus, possibly, more than one component is contemplated and may be employed or used in an implementation of the described embodiments.

The term "equivalent" or "eq. " used in the present invention is the equivalent amount of other raw materials required based on the basic raw material used in each step (1 equivalent) according to the equivalent relationship of the chemical reaction.

The term "dr" or "dr value" used in the present invention refers to the ratio of the content of one diastereomer to another diastereomer, and the higher the dr value, the higher the diastereoselectivity. For example, tert-butyl-4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piperazine-1-carboxylate, i.e., the compound of formula (I-a) of the present invention is diastereomer A, tert-butyl-4- ( (2R, 3S, 4S, 5R) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piperazine-1-carboxylate is diastereomer B. Then dr=diastereomer A/diastereomer B.

The term “comprise” or “include” is an open expression, it means comprising the contents disclosed herein, but don’t exclude other contents.

The term "room temperature" refers to 10℃～40℃, in some embodiments, "room temperature" refers to 10℃～30℃; in other embodiments, "room temperature" refers to 20℃～30℃; in still other embodiments, "room temperature" refers to 20℃, 22.5℃, 25℃, 27.5℃, etc.

In the context of the present invention, all numbers disclosed herein are approximations. The value of each number may vary by 1%, 2%, 5%, 7%, 8%or 10%. When a number with an N value is made public, any number within N+/-1%, N+/-2%, N+/-3%, N+/-5%,N+/-7%, N+/-8%, or N+/-10%will be opened clearly, wherein "+/-" means plus or minus. Whenever a lower limit, DL, and an upper limit, DU, of a numerical range are disclosed, any value within that disclosed range is expressly disclosed.

After the reaction proceeds to a certain extent in the present invention, such as the raw material is consumed more than 70%, more than 80%, more than 90%, more than 95%, or completely by monitoring, the reaction mixture is worked up, such as cooled, collected, drawn, filtered, separated, purified or a combination thereof. The reaction can be monitored by conventional method such as thin-layer chromatography (TLC) , high performance liquid chromatography (HPLC) , gas chromatography (GC) , and the like. The reaction mixture can be worked up by conventional method, for example, the crude product can be collected by concentrating the reaction mixture through vacuum evaporation or conventional distillation and is used directly in the next operation; or the crude product can be obtained by filtration of the reaction mixture and is used directly in the next operation; or the crude product can be got by pouring the supernatant liquid of the reaction mixture after standing a while and is used directly in the next operation; or choose an appropriate organic solvent or its combinations for extraction, distillation, crystallization, column chromatography, rinsing, slurrying and other purification steps.

The solvent used for the reaction of the invention is not particularly restricted, any solvent is contained in the invention so long as it can dissolve the raw materials to a certain extent and doesn't inhibit the reaction. Additionally, many similar modifications in the art, equivalent replacements, or solvent, solvent composition and the solvent composition with different proportions which are equivalent to those described in the invention, all are deemed to be included in the present invention. The present invention gives the preferred solvent for each reaction step.

The amount of water in the solvent is not particularly restricted, that is, the amount of water in the solvent does not affect the reaction in the present invention. Any solvent containing a certain amount of water that can be used in the reaction disclosed herein to a certain extent is deemed to be included in the present invention. The amount of water in the solvent is approximately less than 0.05%, less than 0.1%, less than 0.2%, less than 0.5%, less than 5%, less than 10%, less than 25%, less than 30%, or 0%. In some embodiments, the amount of water in the solvent is within a certain range, which is more conducive to the reaction; for example, in the step of using ethanol as the reaction solvent, using absolute ethanol is more favorable to the reaction. In some embodiments, the amount of water in the solvent exceeds a certain range, which may affect the progress of the reaction (for example, affect the yield of the reaction) , but does not affect the occurrence of the reaction.

Crystal form can be identified by a variety of technical means, such as X-ray powder diffraction (XRPD) , infrared absorption spectroscopy (IR) , melting point method, differential scanning calorimetry (DSC) , thermogravimetric analysis (TGA) , Nuclear magnetic resonance, Raman spectroscopy, X-ray single crystal diffraction, dissolution calorimetry, scanning electron microscopy (SEM) , quantitative analysis, solubility and dissolution rate.

X-ray powder diffraction (XRPD) can detect changes in crystal form, crystallinity, crystal state and other information, which is a common means for identifying crystal form. The peak position of the XRPD pattern primarily depends on the structure of the crystal form and is relatively insensitive to the experimental details, and its relative peak height depends on many factors associated with sample preparation and instrument geometry. Thus, in some embodiments, the crystal formcrystal form of the present invention is characterized by an XRPD pattern having certain peak positions, which is substantially as shown in the XRPD pattern provided in the drawings of the present invention at the same time, the 2θof the XRPD pattern can be measured with an experimental error. The measurement of 2θof the XRPD pattern may be slightly different between the different instruments and the different samples. Therefore, the value of 2θcannot be regarded as absolute. According to the condition of the instrument used in this test, the diffraction peak has an error tolerance of±0.2°.

Differential Scanning Calorimetry (DSC) is a technique of measuring the energy difference between a sample and an inert reference (commonly usedα-Al₂O₃) with temperature by continuously heating or cooling under program control The endothermic peak height of the DSC diagram depends on many factors associated with sample preparation and instrument geometry, while the peak position is relatively insensitive to experimental details. Thus, in some embodiments, the crystal form of the present invention is characterized by an DCS diagram having certain peak positions, which is substantially as shown in the DCS diagram provided in the drawings of the present invention at the same time, the DCS diagram can be measured with an experimental error. The peak position and peak value of DCS diagram may be slightly different between the different instruments and the different samples. Therefore, the peak position or the peak value of the DSC endothermic peak cannot be regarded as absolute. According to the condition of the instrument used in this test, the endothermic peak has an error tolerance of±3℃.

Thermogravimetric analysis (TGA) is a technique for measuring the quality of a substance with temperature under the control of a program. It is suitable for examining the process of the solvent loss or the samples sublimation and decomposition. It can be presumed that the crystal contains crystal water or crystallization solvent. The quality variety of the TGA diagram shown depend on a number of factors, contains the sample preparation and the instrument. The quality variety of the TGA test may be slightly different between the different instruments and between the different samples. According to the condition of the instrument used in this test, there is a±0.1%error tolerance for the mass change.

In the context of the present invention, the 2θvalues in the X-ray powder diffraction pattern are in degrees (°) .

The term "substantially as shown in the figure" refers to at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%, or at least 99%of the peaks are shown in the X-ray powder diffraction pattern or DSC diagram or Raman spectra pattern or infrared spectra pattern.

The "peak" refers to a feature that a person skilled in the art can recognize without belonging to background noise when referring to a spectrum or/and data that appears in the figure.

The present invention relates to the crystal form of said tert-butyl-4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piper azine-1-carboxylate, that is compound of formula (I-a) , which exists in a substantially pure crystal form.

"Substantially pure" means that a crystal form is substantially free of another or more crystal forms, that means the purity of the crystal form is at least 80%, or at least 85%, or at least 90%, or at least 93%, or at least 95%, or at least 99%, or at least 99%, or at least 99.5%, or at least 99.6%, or at least 99.7%, or at least 99.8%, or at least 99.9%, or a crystal form containing other crystal form. The percentage of the other crystals in the total volume or total weight of the crystal forms is less than 20%, or less than 10%, or less than 5%, or less than 3%, or less than 1%, or less than 0.5%, or less than 0.1%, or less than 0.01%.

"Substantially free" means that the percentage of one or more other crystal forms in the total volume or total weight of the crystal forms is less than 20%, or less than 10%, or less than 5%,or less than 4%, or less than 3%, or less than 2%, or less than 1%, or less than 0.5%, or less than 0.1%, or less than 0.01%.

"Relative strength" (or "relative peak height" ) in the XRPD diagram means the ratio of the intensity of the other peaks to the intensity of the first strong peak when the intensity of the first strong peak in all the diffraction peaks of the X-ray powder diffraction pattern is 100%.

General Synthesis and Detection Methods

In the present invention, if the chemical name of the compound doesn’t match the corresponding structure, the compound is characterized by the corresponding structure.

Persons skilled in the art will recognize that the chemical reactions described herein can be used to suitably prepare many compounds similar to those described in this invention. Those skilled in the art can also realize the present invention by modifying methods, such as by appropriately protecting groups, by using other known reagents in addition to those described in the present invention, or by making some conventional modifications to the reaction conditions. These conventional preparation methods modifications should also be regarded as belonging to the scope of the present invention. Alternatively, the reaction or known reaction condition disclosed herein are also recognized to be suitable for the preparation of other compounds similar to the compound described herein.

Generally, the method described herein can prepare the compound of formula (I-a) of the present invention. The following examples are presented to further exemplify the invention.

The structures of the compounds are identified by nuclear magnetic resonance (¹H-NMR, ¹³C-NMR) . ¹H-NMR and ¹³C-NMR chemical shifts (δ) are recorded as ppm (10-6) . ¹H-NMR and ¹³C-NMR are measured with Bruker Ultrashield-400 nuclear magnetic resonance spectrometer and Bruker Avance III HD 600 nuclear magnetic resonance spectrometer, and the measurement solvent is deuterated chloroform (CDCl₃) , deuterated methanol (CD₃OD) or deuterated DMSO (DMSO-d₆) , with TMS (0 ppm) or deuterated chloroform (7.26 ppm) as the reference standard. When peak multiplicities are reported, the following abbreviations are used: s (singlet) , d (doublet) , t (triplet) , m (multiplet) , br (broadened) , dd (doublet of doublets) , dt (doublet of triplets) , ddd (doublet of doublet of doublets) , ddt (doublet of doublet of triplets) , td (triplet of doublets) , brs (broadened singlet) . Coupling constants J, when given, are reported in Hertz (Hz) .

MS spectra were determined on Agilen-6120 Quadrupole LC/MS mass spectrometer;

The thin-layer silica gel used was Yantai Huanghai HSGF254 silica gel plate.

The staring materials of the present invention were known or purchased from Shanghai Accela Company, Energy Company, J&K, Chengdu Aiertai Company, Alfa Company and the like, or they could be prepared by the conventional synthesis methods in the prior art.

Unless otherwise stated, the reactions disclosed herein were carried out in a nitrogen atmosphere.

The term “nitrogen atmosphere” refers to such an atmosphere that a reaction flask was equipped with a balloon or a stainless steel autoclave filled with about 1 L nitrogen.

The term “hydrogen atmosphere” refers to such an atmosphere that a reaction flask was equipped with a balloon or a stainless steel autoclave filled with about 1 L hydrogen.

Unless otherwise stated, the solution used in the examples disclosed herein was an aqueous solution.

Unless otherwise stated, the reaction temperature was room temperature.

The reaction process in the examples was monitored by thin layer chromatography (TLC) . The solvent system for development of a TLC plate comprised dichloromethane and methanol, dichloromethane and ethyl acetate, petroleum ether and ethyl acetate. The volume ratio of the solvents in the solvent system was adjusted according to the polarity of the compounds.

HPLC refers to High Performance Liquid Chromatography.

HPLC was determined on Agilent 1200DAD high pressure liquid chromatography spectrometer (Zorbax Eclipse Plus C18 150×4.6 mm chromatographic column) .

The test condition of HPLC: the run time was 30 minutes (min) ; the column temperature was 35℃; the detection was carried out at the wavelength of 210 nm and 254 nm using PDA detector;

The mobile phase was H₂O (A) and acetonitrile (B) ; and the flow rate was 1.0 mL/min.

The following abbreviations are used throughout the specification:

DESCRIPTION OF THE DRAWINGS

Figure 1 is the differential scanning calorimetry (DSC) diagram of the crystal form A of the compound of formula (I-a) of the present invention.

Figure 2 is the thermal gravimetric analysis (TGA) diagram of the crystal form A of the compound of formula (I-a) of the present invention.

Figure 3 is the unit cell diagram of the crystal form A of the compound of formula (I-a) of the present invention.

Figure 4 is the X-ray powder diffraction (XRPD) pattern of the crystal form A of the compound of formula (I-a) of the present invention.

SCHEME

The compound of formula (I) can be obtained according to the above synthesis scheme. Wherein, the reduction and cyclization reactions in the last step may refer to the method described in the prior arts (as referred to in the present invention) , and the compound of formual (I) may be obtained through the method provided herein. In the synthetic scheme, the compound of formula (I) is prepared with high yield and high purity by using the compound of formula (II-a) or (I-a) as the starting material, and the reaction conditions of each step are mild and the operation is simple, which is suitable for industrial production. Among them, the compound of formula (I-a) is an important intermediate, which can be used to prepare the compound of formula (I) with high yield and high purity. Methods for preparing the compound of in formula (I) using the compound of formula (I-a) include, but are not limited to, those described in embodiments of the present invention.

EXAMPLES

The invention will now be further described by way of example without limiting the invention to the scope of the invention.

The X-ray powder diffraction analysis method used in the present invention was an Empyrean diffractometer, and an X-ray powder diffraction pattern was obtained using Cu-Kαradiation (45 KV, 40 mA) . The powdery sample was prepared as a thin layer on a monocrystalline silicon sample rack and placed on a rotating sample stage, analyzed at a rate of 0.0167°steps in the range of 3°-40°or 3°-60°. Data Collector software was used to collect data, HighScore Plus software was used to process data, Data Viewer software was used to read data.

The differential scanning calorimetry (DSC) analysis method used in the present invention is a differential scanning calorimeter using a TA Q2000 module with a thermal analysis controller. Data were collected and analyzed using TA Instruments Thermal Solutions software. Approximately 1-5 mg of the sample was accurately weighed into a specially crafted aluminum crucible with a lid and analyzed from room temperature to about 300℃ using a linear heating device at 10℃/min. During use, the DSC chamber was purged with dry nitrogen.

The thermal gravimetric analysis (TGA) method used in the present invention is: using a TA Q500 module with a thermal analysis controller to carry out the thermogravimetric analysis. Data were collected and analyzed using TA Instruments Thermal Solutions software. Approximately 10-30 mg of the sample was put into a platinum crucible and analyzed from room temperature to about 300℃ using a linear heating device at 10℃/min. During use, the TGA chamber was purged with dry nitrogen.

The examples of the present invention disclose the method for preparing optically pure tert-butyl-4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piperazine-1-carboxylate, i.e., the compound of formula (I-a) . Skilled in the art can learn from this article to properly improve the process parameters to implement the preparation method. Of particular note is that all similar substitutions and modifications to the skilled person is obvious, and they are deemed to be included in the present invention. Related person can clearly realize and apply the techniques disclosed herein by making some changes, appropriate alterations or combinations to the methods without departing from spirit, principles and scope of the present disclosure.

In order to further understand the invention, it is detailed below through examples.

Examples

Example 1 Synthesis of tert-butyl 4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piperazine-1-carboxylate (the compound of formula (I-a) )

Step 1 Synthesis of (3R, 4S, 5R, 6R) -3, 4, 5-tribenzyloxy-6- (benzyloxymethyl) tetrahydropyran-2-one

A solution of sodium bicarbonate (46.6 g, 555 mmol) in water (450 mL) was added to a solution of 2, 3, 4, 6-tetra-O-benzyl-D-glucopyranose (50.0 g, 92.5 mmol) in dichloromethane (450 mL) , and the mixture was cooled to 0℃. Potassium bromide (6.6 g, 55 mmol) and TEMPO (2.19 g, 13.9 mmol) were added, and the mixture was stirred for 2 min. Then NaClO solution (120 g, 270 mmol, available chlorine 4.0 mass%) was added, and the resulting mixture was stirred for 1 h. The solution was separated, washed with water (50 mL) and saturated brine (50 mL) , dried over anhydrous sodium sulfate, then filtered, and concentrated under vacuum to obtain the title compound as yellow oil (48.6 g, 90.2 mmol, yield: 97.6%) .

Step 2 Synthesis of tert-butyl 4- [ (2R, 3S, 4R, 5R) -2, 3, 4, 6-tetrabenzyloxy-5-hydroxy-hexanoyl] piperazine-1-carboxylate

At room temperature, N-Boc piperazine acetate (227.5 g, 923.7 mmol) in toluene (400 mL) was slowly dropwise added to a solution of (3R, 4S, 5R, 6R) -3, 4, 5-tribenzyloxy-6- (benzyloxymethyl) tetrahydropyran-2-one (199.0 g, 396.5 mmol) in toluene (600 mL) under N₂, and the mixture was stirred for 12 h under the temperature. After the reaction was completed, to the system was added water (500 mL) . The mixture was stirred for 10 min, then stood and separated, the upper organic phase was washed once with saturated sodium chloride aqueous solution (800 mL) , then n-heptane (3.0 L) was added dropwise and the mixture was cloudy. The mixture was stirred at room temperature for 4-5 h, and a large amount of white solid was precipitated out. The mixture was cooled to 10℃ and continued to stir for 3 h, and then filtered with suction. The wet product was added into toluene (600 mL) and stirred to dissolve, then n-hexane (1.6 L) was added, and the mixture was stirred and crystallized for 12 h. An off-white solid was precipitated out and filtered by suction. The solid was rinsed with a small amount of n-heptane (150 mL) , collected and dried in vacuo at 40℃ to obtain the title compound as an off-white solid (153.2 g, 211.36 mmol, yield: 56.8%) .

Step 3 Synthesis of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (the compound of formula (II-a) )

DMSO (900 mL) and DIPEA (800 mL, 4828.4 mmol) were added to tert-butyl 4- [ (2R, 3S, 4R, 5R) -2, 3, 4, 6-tetrabenzyloxy-5-hydroxy-hexanoyl] piperazine-1-carboxylate (500.0 g, 689.8 mmol) in toluene (1.5 L) , and the mixture was cooled to 0℃ under N₂, then sulfur trioxide pyridine (384.2 g, 2415.2 mmol) was added in portions at 0-5℃. After the addition was completed, the mixture was stirred at 0-5℃ for 2 h. A small amount of raw material was found to not react completely by using TLC to track, then sulfur trioxide pyridine (100 g) was added and the resulting mixture was continuously stirred until TLC point plate monitoring showed that the reaction was complete. The reaction system was washed by adding tap water (2.5 L) , then separated; the upper organic phase was washed with saturated brine (500 mL×3) , dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under vacuum. The residue was dissolved in THF (2000 mL) , then silica gel (100 g) and activated carbon (50 g) were added and the mixture was stirred for 20 min, and then filtered. The filtrate was concentrated under vacuum to obtain the title compound as red oil (470.0 g, 650.2 mmol, yield: 94.2%) .

Step 4 Synthesis of tert-butyl 4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piperazine-1-carboxylate (the compound of formula (I-a) )

Embodiment 1:

Under N₂, TMEDA (48.7 mL, 325.1 mmol) was slowly added to a solution of trimethylsilylacetylene (110.2 mL, 780.2 mmol) in THF (1.0 L) at-78℃, the mixture was stirred for 10 min and then LiHMDS (780.2 mL, 1mol/L) was slowly added dropwise. After stirring for 30 min, to the resulting mixture was slowly dropwise added a solution of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (the compound of formula (II-a) ) (470.0 g, 650.2 mmol) in THF (1.0 L) , and the mixture was reacted at-78℃ for 2 h. Aftering diluting with ethyl acetate (1.0 L) , the reaction was quenched with saturated ammonium chloride aqueous solution (1.0 L) and then separated, and the upper organic phase was washed with 10%citric acid aqueous solution (2.0 L) until the aqueous phase was weakly acidic (pH about 3～5) , then washed with saturated brine (500 mL) . The organic phase was concentrated under vacuum to near dryness, and MeOH (800 mL) and K₂CO₃ (100 g) were added to the concentrated oil at 0℃; then the mixture was stirred at room temperature and monitored by TLC, and the reaction was complete in about 0.5-2 h. The resulting solution was filtered until the filtrate was concentrated to near dryness to obtain the title compound as red oil (480 g, HPLC purity: 80.8%, dr value was 86: 14) . Isopropyl ether (960 mL) was added to the red oil, and the mixture was heated at 60℃ until completely dissolved. The seed crystal was added at room temperature, and the mixture was stirred for 2-4 h, then stirred for 1 h at 0℃ and filtered with suction. The solid was washed with isopropyl ether (50.0 mL×2) at 0℃ to obtain a white powdery solid, which was the crystal form A of the compound of formula (I-a) (233.0 g, 311.11 mmol, yield: 48.0%, HPLC purity: 98.42%, dr value>99: 1) .

Identification of the crystal form A of the compound of formula (I-a) :

(1) LC-MS: calcd. for C₄₅H₅₃N₂O₈ ⁺ [M+H] ⁺: 749.4; found: 749.3;

(2)

¹H NMR (400 MHz, CDCl₃) δ7.39–7.23 (m, 20H) , 4.91 (dd, J=11.6, 6.4 Hz, 2H) , 4.74 (dd, J=20.8, 10.8 Hz, 2H) , 4.68–4.47 (m, 6H) , 4.05 (d, J=3.6 Hz, 1H) , 3.84 (s, 1H) , 3.65 (s, 2H) , 3.59–3.36 (m, 4H) , 3.36–2.94 (m, 4H) , 2.54 (s, 1H) , 1.48 (s, 9H) ;

¹³C NMR (100 MHz, CDCl₃) δ168.4, 154.5, 138.2, 137.8, 137.7, 137.0, 128.7, 128.5, 128.4, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.8, 127.6, 84.6, 80.2, 79.1, 78.2, 77.3, 77.0, 76.8, 75.1, 74.7, 74.6, 73.7, 73.2, 73.0, 72.7, 45.0, 42.3, 28.4.

(3) Analysis and identification by TA Q2000 Differential Scanning Calorimetry: the scanning speed is 10℃/min and it contains an endothermic peak of 93.12℃. There is an error tolerance of±3℃.

(4) Analysis and identification by TA Q500 thermal gravity loss (TGA) : the heating rate is 10℃/min, when heated to 150.09℃, the weight loss is 0.1199%, and there is an error tolerance of±0.1%.

(5) Analysis and identification by Empyrean X-ray powder diffraction (XRPD) : using Cu-Kαradiation, it has the following characteristic peaks expressed in angle 2θ: 5.72°, 5.92°, 8.62°, 11.32°, 11.82°, 12.38°, 12.97°, 13.35°, 14.91°, 15.29°, 15.57°, 16.51°, 17.02°, 17.33°, 17.76°, 19.40°, 19.86°, 20.26°, 20.93°, 21.59°, 22.22°, 22.52°, 23.85°, 25.21°, 25.75°, 26.40°, 26.93°, 29.84°, 30.32°, 32.57°, 37.05°, 38.44°, and there is an error tolerance of±0.2°.

Embodiments 2-15:

Trimethylsilylacetylene, an additive and THF (2.0 mL) were added to a 10 mL reaction tube, and to the mixture cooling to a certain reaction temperature and stirring for 10 min was added LiHMDS. After stirring for 15-30 min at the same temperature, a solution of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (the compound of formula (II-a) ) (0.72 g, 1.0 mmol) in THF (2.0 mL) was added, and the mixture was stirred for 1-2 h at the temperature. The point plate was used to monitor whether the reaction was complete. Post-processing: the reaction solution was diluted with ethyl acetate (10 mL) , quenched with 1 M hydrochloric acid aqueous solution (adjusting the pH to 3～5) , and then separated. The upper organic phase was concentrated under vacuum to nearly dryness to give a concentrated oil, to which were added MeOH (2.0 mL) and K₂CO₃ (0.2 g) . The mixture was stirred at room temperature and monitored by TLC, and the reaction was complete in about 0.5～2 h. After the TMS group was basically completely removed, the insoluble matter was filtered out, and a small amount of organic phase was diluted and analyzed by HPLC. The additives and their amounts, the amount of trimethylsilylacetylene, the amount of LiHMDS and the reaction temperature in Embodiments 2-15 and the experimental results thereof are shown in Table 1.

Table 1:

Note: "─" means not added or not present.

Embodiments 16-17:

Trimethylsilylacetylene (0.15 mL, 1.1 eq. ) and THF (2.0 mL) were added to a 10 mL reaction tube, and TMEDA (165.0μL, 1.1 eq. ) was added or not added, the mixture was cooled to -78℃ and stirred for 10 min, then n-BuLi (1.1 mL, 1.0 mol/L) was added, the mixture was kept the temperature and stirred for 15-30 min, then a solution of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (the compound of formula (II-a) ) (0.72 g, 1.0 mmol) in THF (2.0 mL) was added and the mixture was kept the temperature and stirred for 1～2 h, and then the point plate was used to monitor whether the reaction was complete. Post-processing: the reaction solution was diluted with ethyl acetate (10 mL) , then quenched by adding 1 M hydrochloric acid aqueous solution (adjusting the pH to 3～5) , and separated, the upper organic phase was concentrated under vacuum to nearly dryness, then MeOH (2.0 mL) and K₂CO₃ (0.2 g) were added to the concentrated oil, the mixture was stirred at room temperature after addition and monitored by TLC, the reaction was complete in about 0.5～2 h. After the TMS group was basically completely removed, the insoluble matter was filtered out, and a small amount of organic phase was diluted and sent for HPLC analysis. Results were as shown in table 2.

Table 2:

Note: "─" means not added or not present.

The experimental results show that when trimethylsilylacetylene and n-BuLi are used for the reaction, adding or not adding TMEDA has little effect on the dr value, but it will affect the HPLC purity, the HPLC purity is lower when adding TMEDA; when trimethylsilylacetylene and LiHMDS are used for the reaction, as shown in the experimental results in Embodiments 2-15, the HPLC purity and dr value of the obtained product are high, and the effect of adding TMEDA (Embodiment 4) is significantly better than that without TMEDA (Embodiment 5) , the HPLC purity and dr value are increased by about 10%. It can be seen that different organolithium reagents have different reaction results with or without TMEDA. In addition, n-BuLi is dangerous, flammable and explosive, and has a fire risk, so it is not suitable for industrial scale-up.

Embodiment 18:

A solution of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (the compound of formula (II-a) ) (0.72 g, 1.0 mmol) in THF (3.0 mL) was added to a 10 mL reaction tube, the mixture was cooled to-20℃ and stirred for 30 min, then ethynylmagnesium bromide (5.0 mL, 0.5 mol/L) was added and the mixture was kept the temperature and stirred for 1-2 h, and then the point plate was used to monitor whether the reaction was complete. Post-processing: the reaction solution was diluted with ethyl acetate (10 mL) , quenched by adding 1 M hydrochloric acid aqueous solution (adjusting the pH to 3-5) , and then separated, and the upper organic phase was diluted and sent for HPLC analysis. Results were as shown in table 3.

Table 3:

Note: "─" means not added or not present.

The experimental results show that when the Grignard reagent ethynylmagnesium bromide is used for the reaction, the diastereoselectivity of the obtained product is low, and the dr value is 53.4: 46.6; when trimethylsilylacetylene and LiHMDS are used for the reaction, as shown in the experimental results in Embodiments 2-15, the diastereoselectivity of the obtained product is significantly higher, and the dr value is≥74: 26. In addition, ethynylmagnesium bromide is not only expensive, but its quality is difficult to guarantee, so it is not suitable for industrial scale-up.

Embodiments 19-21:

Trimethylsilylacetylene (0.17 mL, 1.2 eq. ) , metal salt (M) , chiral ligand (L) , additives and THF (2.0 mL) were added into a 10 mL reaction tube, the mixture was cooled to-78℃ and stirred for 10 min, then LiHMDS (1.2 mL, 1.0 mol/L) was added, the mixture was kept the temperature and stirred for 15-30 min, then a solution of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (the compound of formula (II-a) ) (0.72 g, 1.0 mmol) in THF (2.0 mL) was added, the mixture was kept the temperature and stirred for 1～2 h, then the point plate was used to monitor whether the reaction was complete. Post-processing: the reaction solution was diluted with ethyl acetate (10 mL) , then quenched by adding 1 M hydrochloric acid aqueous solution (adjusting the pH to 3～5) , and separated, the upper organic phase was concentrated under vacuum to nearly dryness, then MeOH (2.0 mL) and K₂CO₃ (0.2 g) were added to the concentrated oil, the mixture was stirred at room temperature after addition and monitored by TLC, the reaction was complete in about 0.5～2 h. After the TMS group was basically completely removed, the insoluble matter was filtered out, and a small amount of organic phase was diluted and sent for HPLC analysis. Table 4 shows the metal salts (M) , chiral ligands (L) , additives and their amounts, reaction temperatures and experimental results in Embodiments 19-21.

Table 4:

Note: "─" means not added or not present; "NR" means no reaction.

The experimental results show that when Zn (OTf) ₂ and Salen ligand, or highly active diethylzinc and R- (+) -BINOL ligand are used as a Lewis acid to activate the carbonyl to control the chiral environment, thereby improving the diastereoselectivity of the reaction, the results are all not good; and when the common additive TMEDA is used, as the experimental results shown in Embodiments 2-15, the high diastereoselectivity control can be achieved, and the purity of the resulting product is relatively high. In addition, metal salts (M) and chiral ligands (L) are expensive and costly.

Embodiment 22:

Trimethylsilylacetylene (9.51 g, 96.84 mmol) was added to the mixture of lithium bis (trimethylsilyl) amide (81.5 g, 94.77 mmol, 1 mol/L in THF solution) and N, N, N′, N′-Tetramethylethylenediamine (11.09 g, 95.45 mmol) which was cooled to-78℃ under N₂. After stirring for 120 min at the temperature, a solution of tert-butyl 4- [ (2R, 3S, 4S) -2, 3, 4, 6-tetrabenzyloxy-5-oxohexanoyl] piperazine-1-carboxylate (50.00 g, 69.17 mmol, purity: 98.72%) in THF (70 g) was added, and the resulting mixture was stirred at-78℃ for 30 min. Then MeOH (79 g) was added. The mixture was concentrated under vacuum after stirring for 0.5 h. To the concentrate was added isopropyl ether (109 g) , and the mixture was stirred to dissolve, washed with a solution of citric acid (25 g) in water (100 g) and then separated. The target phase was concentrated under vacuum to give a concentrate to which was added isopropyl ether (109 g) . The mixture was stirred at 60℃ to dissolve, then cooled to 20℃～30℃and stirred for 5 h. Further cooling to 0℃ and stirring for 1 h, crystals was precipitated. A filter cake was obtained by centrifugation, then washed with isopropyl ether (36 g) of 0℃, collected, and dried in vacuo at 45℃ for 6 hours to obtain the title compound as a white solid (37.07 g, 49.5 mmol, product content: 99.47%, yield: 71.56%) .

Example 2 Single crystal cultivation of the crystal form A of the compound of formula (I-a)

The crystal form A of tert-butyl-4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piper azine-1-carboxylate (the compound of formula (I-a) ) (30 mg, 0.040 mmol) prepared in Example 1 was weighed to a 5.0 mL round bottom flask, and ethyl acetate (0.5 mL) was added, the mixture was heated to dissolve slightly, then n-heptane (2.5 mL) was added slowly, and the mixture was stood in a refrigerator at 4℃, and then single crystals were precipitated after 10 days.

Example 3 X-ray single crystal diffraction research of the single crystal of the crystal form A of the compound of formula (I-a)

The data was collected on an Agilent Technologies Gemini A Ultra diffractometer with Cu Kα radiationThe measured intensity data was indexed and processed by using the CrysAlis PRO program. The unit cell parameters were determined through pre-experiments, and the data collection strategy was formulated according to the unit cell parameters for data collection.

Structure analysis and refinement were performed by using HELX-97 (Sheldrick, G. M. SHELXTL-97, Program for Crystal Structure Solution and Refinement; University of Gottingen: Gottingen, Germany, 1997) program, and analyzed by the direct method. The derived atomic parameters (coordinates and temperature factors) were corrected by full matrix least squares. The function∑_w (|F_o|-|F_c|) ² minimized in the correction. R is∑||F_o|-|F_c||/∑|F_o|, and R_w is [∑_w (|F_o|-|F_c|) ² /∑_w|F_o|₂] ^1/2, wherein w is a suitable weighting function based on the error in the observed intensities. Difference maps are checked at all stages of correction. Except the positions of hydrogen atoms H1N and H2N were determined by difference Fourier map, the positions of other hydrogen atoms were obtained by theoretical calculation. The simulated X-ray powder diffraction patterns were calculated by using Mercury software.

Suitable size single crystals (the single crystal of crystal form A of the compound of formula (I-a) prepared in Example 2) were selected for single crystal diffraction analysis. The selected crystals were fixed on fine glass fibers with a small amount of petroleum jelly, then installed on an Agilent Technologies Gemini A Ultra diffractometer, and measured at a temperature of about 150 K to obtain the unit cell parameters as shown in Table 5 and fractional atomic coordinates as shown in Table 6.

Table 5 The unit cell parameters of the single crystal of the crystal form A of the compound of formula (I-a)

Table 6 The fractional atomic coordinates of the single crystal of the crystal form A of the compound of formula (I-a)

Example 3 Synthesis of tert-butyl 4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxy-6-oxoheptanoyl) piperazine-1-carboxylate

To a flask were added tert-butyl 4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxyhept-6-ynoyl) piperazine-1-carboxylate (749 mg, 1.00 mmol, purity: 98.42%) , acetonitrile (1.58 g) , cuprous oxide (29 mg, 0.20 mmol) , 1, 8-diazabicyclo [5.4.0] undec-7-ene (76 mg, 0.50 mmol) and drinking water (36 mg, 2.00 mmol) . N₂ gas was replaced for three times after the addition and CO₂ was charged to a pressure of 1 MPa. The mixture was heated to 60℃and stirred for 18 h, and then cooled to 10℃after reacting completely. To the reaction solution was added citric acid aqueous solution (1.0 mL) , and the mixture was concentrated under vacuum to give a concentrate which was dissolved in ethyl acetate (5 mL) and then washed with water (5 mL×2) . The organic layer was concentrated under vacuum to obtained the title compound as yellow oil (770 mg, 1.00 mmol, product content: 66.44%, yield: 100%) . MS (ESI, pos. ion) m/z: 767.4 [M+H] ⁺.

Example 4 Synthesis of tert-butyl 4- ( (2R, 3S, 4S, 5R, 6R) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5, 6-dihydroxyheptanoyl) piperazine-1-carboxylate

To a flask were added tert-butyl 4- ( (2R, 3S, 4S, 5S) -2, 3, 4-tribenzyloxy-5- ( (benzyloxy) methyl) -5-hydroxy-6-oxoheptanoyl) piperazine-1-carboxylate (10 g, 13.04 mmol, purity: 98.26%) and methyl tert-butyl ether (296 g) . The mixture was cooled to 0℃, to which was added lithium aluminum tert-butoxy-hydride (9.95 g, 39.12 mmol) . The reaction mixture was stirred for 2 h after the addition. To the mixture was added water (10 g) , and the resulting mixture was stirred for 10 min, then filtered with suction to give a filter cake which was soaked with methyl tert-butyl ether (30 g) . The filtrate was collected, washed with 1 M HCl solution (200 g) , and concentrated under vacuum to obtained the title compound as yellow oil (10.03 g, 13.00 mmol, product content: 92.81%, yield: 100%) .

Example 5 Synthesis of tert-butyl 4- ( (2R, 3S, 4S) -2, 3, 4-tris (benzyloxy) -4- ( (4R, 5R) -4- ( (benzyloxy) methyl) -2, 2, 5-trimethyl-1, 3-dioxolan-4-yl) butanoyl) piperazine-1-carboxylate

Tert-butyl 4- ( (2R, 3S, 4S, 5R, 6R) -2, 3, 4-tris (benzyloxy) -5- ( (benzyloxy) methyl) -5, 6-dihydroxyheptanoyl) piperazine-1-carboxylate (3.4 g, 4.42 mmol, content: 92.81%) was dissolved in acetone (26.86 g) , to which were added 2, 2-dimethoxypropane (1.38g, 13.26 mmol) and p-toluenesulfonic acid monohydrate (63 mg, 0.33 mmol) , and the mixture was stirred for 1 h. After the reaction was completed, saturated sodium bicarbonate solution (1 mL) was added to the mixture. The resulting mixture was stirred for 10 min, and then concentrated under vacuum. The concentrate was dissolved in ethyl acetate (9.2 g) , washed with water (9.2 g) , and concentrated under reduced under vacuum to obtain the title compound as light yellow oil (3.58 g, HPLC purity: 96.01%, yield: 100%) . LC-MS: calcd. For C₄₈H₆₁N₂O₉ ⁺ [M+H] ⁺: 809.5; found: 809.5.

Example 6 Synthesis of (2R, 3S, 4S) -2, 3, 4-tris (benzyloxy) -4- ( (4R, 5R) -4- ( (benzyloxy) methyl) -2, 2, 5-trimethyl-1, 3-dioxolan-4-yl) -1- (4-chloro-3- (4-ethoxybenzyl) phenyl) butan-1-one

Tert-butyl 4- ( (2R, 3S, 4S) -2, 3, 4-tris (benzyloxy) -4- ( (4R, 5R) -4- ( (benzyloxy) methyl) -2, 2, 5-trimethyl-1, 3-dioxolan-4-yl) butanoyl) piperazine-1-carboxylate (450.50 g, 556.86 mol, product purity: 90.47%) was dissolved in anhydrous tetrahydrofuran (1.21 kg) , and the mixture was cooled to-20℃ under N₂. A solution of (4-chloro-3- ( (4-ethoxyphenyl) methyl) phenyl) magnesium bromide (891.30 mmol, purity: 95.00%) in tetrahydrofuran prepared according to the methods disclosed in the prior arts was added dropwise to the above mixture in about 30 min. After the addition, the mixture was continued stirring at-20℃ for 20 min and then moved to room temperature and stirred for 2 h. The reaction was finished and then quenched with dilute hydrochloric acid solution (1.25 L, 1 mol/L) at 0℃. The resulting mixture was extracted with n-heptane (1.27 kg) , and the organic phase was washed with saturated brine (1.65L) and concentrated under reduced vacuum to obtain the title compound as yellow oil (484.18g, product content: 82.48%, yield: 100%) . HRMS: calcd. for C₅₄H₆₁ClNO₈ ⁺ [M+NH₄] ⁺: 886.4; found: 886.4.

Reference throughout this specification to "an embodiment, " "some embodiments, " "one embodiment" , "another example, " "an example, " "a specific example, " or "some examples, " means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as "in some embodiments, " "in one embodiment" , "in an embodiment" , "in another example, "in an example, " "in a specific example, " or "in some examples, " in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can integrate and combine different embodiments, examples or the features of them as long as they are not contradictory to one another.

Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure.

Claims

A method for preparing a compound of formula (I-a) , comprising the following steps:

the compound of formula (II-a) undergoes an addition reaction with trimethylsilylacetylene in a solvent in the presence of LiHMDS to obtain the compound of formula (I-a) ,
The method of claim 1, the addition reaction is carried out in the presence of an additive; wherein the additive is 2, 4, 6-collidine, piperidine, triethylenediamine, pyrrole, tetramethylethylenediamine, tetramethyltartaramide, hexamethylphosphoric triamide, (-) -sparteine, triethylamine, propylenediamine, ethylenediamine, dimethylamine, N, N-diisopropylethylamine, 1, 8-diazabicyclo [5.4.0] undec-7-ene, 4-dimethylaminopyridine, N, N-dimethylpropenylurea, N-methylpyrrolidone or pyridine.
The method of claim 2, wherein the amount of the additive is 0.2-1.2 times equivalent of the compound of formula (II-a) ; preferably, the amount of the additive is 0.5-1.0 times equivalent of the compound of formula (II-a) ; more preferably, the amount of the additive is 0.2 times, 0.5 times or 1.0 time equivalent of the compound of formula (II-a) .
The method of any one of claims 1-3, wherein the amount of trimethylsilylacetylene is 1.0-2.0 times equivalent of the compound of formula (II-a) ; preferably, the amount of trimethylsilylacetylene is 1.2-1.5 times equivalent of the compound of formula (II-a) ; more preferably, the amount of trimethylsilylacetylene is 1.2 times or 1.5 times equivalent of the compound of formula (II-a) .
The method of any one of claims 1-4, wherein the amount of LiHMDS is 1.0-2.0 times equivalent of the compound of formula (II-a) ; preferably, the amount of LiHMDS is 1.2-1.5 times equivalent of the compound of formula (II-a) ; more preferably, the amount of LiHMDS is 1.2 times or 1.5 times equivalent of the compound of formula (II-a) .
The method of any one of claims 1-5, wherein the solvent is tetrahydrofuran, dichloromethane, toluene, ether, 2-methyl-tetrahydrofuran, n-hexane, cyclohexane or n-heptane.
The method of any one of claims 1-6, wherein in the reaction of the compound of formula (II-a) with trimethylsilylacetylene, the reaction temperature is-40℃～-80℃; preferably, the reaction temperature is-50℃～-80℃; preferably, the reaction temperature is-60℃～-80℃; more preferably, the reaction temperature is-78℃.
A compound of formula (I-a) ,
Crystal form A of the compound of formula (I-a) ,

has at least one of the following characteristics:

1) the differential scanning calorimetry includes a maximum endothermic peak at 93.12℃±3℃; or

2) having the following unit cell parameters:

Unit cell dimensions: α=90°, β=97.3928°, γ=90°;

Space group: P2₁;

Unit cell volume:

The number of asymmetric units Z in the unit cell: 2; or

3) the X-ray powder diffraction pattern has diffraction peaks at the following 2θangles: 5.92°±0.2°, 8.62°±0.2°, 11.32°±0.2°, 12.97°±0.2°, 17.76°±0.2°, 19.86°±0.2°.
The crystal form A of claim 9, which has a differential scanning calorimetry diagram substantially as shown in FIG. 1.
The crystal form A of claim 9 or 10, the X-ray powder diffraction pattern has diffraction peaks at the following 2θangles: 5.72°±0.2°, 5.92°±0.2°, 8.62°±0.2°, 11.32°±0.2°, 12.97°±0.2°, 13.35°±0.2°, 14.91°±0.2°, 15.29°±0.2°, 15.57°±0.2°, 16.51°±0.2°, 17.02°±0.2°, 17.76°±0.2°, 19.40°±0.2°, 19.86°±0.2°, 20.26°±0.2°, 22.52°±0.2°, 23.82°±0.2°.
The crystal form A of any one of claims 9-11, the X-ray powder diffraction pattern has diffraction peaks at the following 2θangles: 5.72°±0.2°, 5.92°±0.2°, 8.62°±0.2°, 11.32°±0.2°, 11.82°±0.2°, 12.38°±0.2°, 12.97°±0.2°, 13.35°±0.2°, 14.91°±0.2°, 15.29°±0.2°, 15.57°±0.2°, 16.51°±0.2°, 17.02°±0.2°, 17.33°±0.2°, 17.76°±0.2°, 19.40°±0.2°, 19.86°±0.2°, 20.26°±0.2°, 20.93°±0.2°, 21.59°±0.2°, 22.22°±0.2°, 22.52°±0.2°, 23.85°±0.2°, 25.21°±0.2°, 25.75°±0.2°, 26.40°±0.2°, 26.93°±0.2°, 29.84°±0.2°, 30.32°±0.2°, 32.57°±0.2°, 37.05°±0.2°, 38.44°±0.2°.
The crystal form A of any one of claims 9-12, which has an X-ray powder diffraction pattern substantially as shown in FIG. 4.