Preparation and application of a base-cleaved connecting arm for solid-phase synthesis of polysaccharides

Abstract

This invention discloses the preparation and application of a base-sensitive linker arm for solid-phase synthesis of polysaccharides, belonging to the fields of glycochemistry and solid-phase synthesis technology. This invention provides a base-sensitive linker arm system comprising an ester core, a linker, and a solid-phase support; one end of the ester core is connected to the solid-phase support, and the other end is connected to the linker; one end of the linker is connected to the ester core, and the other end contains exposed hydroxyl groups; the linker arm system of this invention uses phthalates or alkyl esters as the base-sensitive core structure, which can be cleaved under sodium methoxide conditions, and after hydrogenation deprotection, retains free anomeric sites at the ends of the polysaccharides, or provides amino and carboxyl groups for subsequent preparation of glycoconjugates and glycochips. During the cleavage of the linker arm, the ester protecting groups of the polysaccharide can be removed simultaneously, simplifying the deprotection step and improving efficiency and yield.

Description

Technical Field

[0001] This invention relates to the preparation and application of an alkali-cleaved linker arm for solid-phase synthesis of polysaccharides, belonging to the fields of saccharide chemistry and solid-phase synthesis technology. Background Technology

[0002] Solid-phase synthesis is generally achieved by assembling monomers in the correct order on an insoluble support. After the oligomers with protecting groups are assembled, they are cleaved from the solid support to release their protective groups, followed by overall deprotection, and finally purified by methods such as ion exchange chromatography and reversed-phase high-performance liquid chromatography to obtain the target molecule.

[0003] Solid-phase synthesis technologies for peptides and nucleic acids are relatively mature and have been widely adopted in industrial applications, but the development of solid-phase synthesis of polysaccharides is relatively lagging behind.

[0004] Solid-phase synthesis of glycans can rapidly assemble a group of identical or different monosaccharide building blocks into the desired glycan. Starting from the linker arms bound by the resin, the glycan chains are extended by alternating glycosylation and temporary protecting group removal reactions, and finally the linker arms are cleaved to obtain free glycans.

[0005] In the solid-phase synthesis of glycans, the design and selection of linker arms is one of the core technologies. The linker arms need to remain inert to all reaction conditions throughout the entire solid-phase assembly of the glycan, and should be efficiently cleaved under mild conditions at the end of the synthesis.

[0006] Since the reduced ends of the glycans after linker cleavage will have different chemical modifications, suitable linkers must be selected based on the solid-phase glycan synthesis strategy and the further applications of the glycans. The initially developed alkenyl linkers had poor compatibility with the electrophilic reagents required for thioglycoside activation and low cleavage efficiency. The dedicated UV flow cytometry equipment required for photocleavage of linkers is expensive, has long cleavage times and low yields under normal conditions, and exhibits poor compatibility with some photosensitive groups during use. For example, the amino precursor—azide group—commonly used in glycoamine synthesis is easily decomposed under UV irradiation. Traditional basic-sensitive linker structures are shown below; their synthesis process is cumbersome, and the diazomethane used in the reaction is an explosive and carcinogenic compound. Some raw materials are expensive, difficult to separate and purify during synthesis, and offer only the single option of endowing the glycan with an amino terminus.

[0007] It is a resin. Summary of the Invention

[0008] Technical issues:

[0009] The technical problem solved by this invention is to prepare three linker systems for solid-phase synthesis of glycans simply and rapidly through chemical synthesis and apply them to the solid-phase synthesis of nine types of glycans in four categories. This invention develops novel basic-sensitive linkers that differ from traditional structures, which can rapidly obtain glycans with free reducing ends after solid-phase synthesis; alternatively, carboxyl or amino groups can be retained at the reducing ends of glycans after solid-phase synthesis, facilitating subsequent coupling of glycan chains with carrier proteins or the development of glycan chips for the evaluation of glycan biological functions. The linkers prepared by this invention are simple to synthesize, the raw materials are readily available, and the cleavage is simple, allowing for the efficient preparation of various types of glycans with considerable yield. Among them, the phthalate structure is used for resin modification for the first time, with the following advantages: (1) Compared with alkyl esters, aromatic esters have higher stability under acidic glycosylation reaction conditions. (2) Phthalic anhydride can directly react with the hydroxyl group of the linker to form an ester, while releasing another molecule of free carboxyl group for connecting the solid-phase carrier, making the synthesis operation convenient. (3) The base removal process breaks two ester bonds, and no partially methylated carboxyl groups remain at the end of the linker, providing convenience for subsequent purification.

[0010] Technical solution:

[0011] This invention begins with readily available chemical raw materials and, through simple reaction steps, rapidly and in high yields yields three linker compounds. Connecting these linkers to a solid-phase support, Merrifield resin, yields three linker systems. These linker systems can cleave under alkaline conditions, are orthogonal to most glycosylation reactions, and can be used for the solid-phase synthesis of glycans. After cleavage, the three linker systems can provide different end-modifications for the glycans. Using the synthesized linker systems in the solid-phase synthesis of four glycans yields nine different tetrasaccharides.

[0012] This invention provides an alkaline-sensitive linker system, which includes an ester core, a linker, and a solid support; one end of the ester core is linked to the solid support, and the other end is connected to the linker; one end of the linker is connected to the ester core, and the other end contains exposed hydroxyl groups.

[0013] The structure is as follows:

[0014] in, It has an ester core. For connectors, As a solid-phase support;

[0015] X is Or -(CH2) a -;

[0016] Y is -(CH2) b -,or

[0017] a and b are independently selected from 1, 2, 3, 4, and 5, respectively.

[0018] In one embodiment of the present invention, the solid support is Merrifield resin.

[0019] In one embodiment of the invention, the exposed hydroxyl groups in the linker facilitate the use of glycosylation acceptors for the synthesis of polysaccharides.

[0020] In one embodiment of the present invention, after treating the linker arm with alkaline conditions, the ester core is hydrolyzed, and the linker remains at the reduced end of the polysaccharide.

[0021] In one embodiment of the present invention, the alkaline-sensitive linker system may specifically be: a linker system ① containing an aromatic ester core and a traceless linker, a linker system ② containing an aromatic ester core and an amino linker, or a linker system ③ containing an alkyl ester core and a carboxyl linker; the corresponding structures are shown below:

[0022]

[0023] In one embodiment of the present invention, the linker system ① has a phthalic acid-derived ester core, terephthalic acid as a traceless linker, and Merrifield resin as a solid carrier; after synthesizing the polysaccharide cleavage linker, p-hydroxymethylbenzyl protection is retained at the polysaccharide reduction end, which can be removed by hydrogenation to release the anomeric hydroxyl group at the reduction end of the sugar chain.

[0024] This invention also provides a method for synthesizing a connecting arm system ①, the structure of which is shown below:

[0025]

[0026] In one embodiment of the present invention, the synthesis route of the connecting arm system ① is as follows:

[0027]

[0028] In one embodiment of the present invention, the synthesis method of the connecting arm system ① specifically includes the following steps: terephthalic acid and tert-butyldimethylchlorosilane are reacted with dichloromethane as a solvent, and an alkaline environment is provided by imidazole to protect a hydroxyl group of terephthalic acid with the tert-butyldimethylsilyl protecting group, to obtain compound 1; compound 1 is esterified with phthalic anhydride under the catalysis of 4-dimethylaminopyridine to obtain compound 2; compound 2 is linked with Merrifield resin to obtain resin 3; finally, the tert-butyldimethylsilyl group of resin 3 is removed using tetrabutylamine fluoride to obtain connecting arm system ①.

[0029] In one embodiment of the present invention, during the synthesis of compound 1, the molar ratio of tert-butyldimethylchlorosilane to terephthalic acid is 0.6:1.

[0030] In one embodiment of the present invention, the reaction condition for converting p-phenylenediethanol into compound 1 is overnight stirring at room temperature.

[0031] In one embodiment of the present invention, during the synthesis of compound 2, the molar ratio of compound 1 to phthalic anhydride is 1:2.

[0032] In one embodiment of the present invention, the synthesis conditions of compound 2 are a room temperature reaction and a reaction time of 3 hours.

[0033] In one embodiment of the present invention, during the synthesis of compound 3, the initial loading of Merrifield resin is 1 mmol / g.

[0034] In one embodiment of the present invention, during the synthesis of compound 3, the molar ratio of compound 2 to Merrifield resin is 1:0.5. The amount of compound 2 relative to Merrifield resin is 2 mmol / g.

[0035] In one embodiment of the present invention, during the synthesis of compound 3, the molar ratio of cesium carbonate to compound 2 is 1.5:1.

[0036] In one embodiment of the present invention, during the synthesis of compound 3, the molar ratio of tetrabutylammonium iodide to compound 2 is 0.5:1.

[0037] In one embodiment of the present invention, during the synthesis of compound 3, the solvent is N,N-dimethylformamide, the reaction temperature is 60°C, and the reaction is carried out by shaking for 24 hours.

[0038] In one embodiment of the present invention, during the synthesis of compound 3 into the connecting arm system ①, the amount of tetrabutylamine fluoride relative to the aforementioned Merrifield resin is 1 mmol / g. The molar ratio of tetrabutylamine fluoride to the aforementioned Merrifield resin is 1:1.

[0039] In one embodiment of the present invention, during the synthesis of compound 3 into the connecting arm system ①, the solvent is tetrahydrofuran, the reaction temperature is room temperature, and the reaction is carried out overnight with shaking.

[0040] In one embodiment of the present invention, the connecting arm system ① was measured to have a loading of 0.63 mmol / g using the method described in An accurate method for the quantitation of Fmoc-derivatized solid phase supports. Gude, M. Letters in Peptide Science 9, 203-206 (2002).

[0041] In one embodiment of the present invention, the linker system ② has phthalate as the ester core, aminopentanol derivative linkers, and Merrifield resin as the solid support. After synthesizing the polysaccharide, cleaving the linker, and deprotecting, the five-carbon-linked amino group can be retained at the reduced end of the polysaccharide.

[0042] The present invention also provides a method for synthesizing a connecting arm system ②, the structure of which is shown below:

[0043]

[0044] In one embodiment of the present invention, the synthesis route of the connecting arm system ② is as follows:

[0045]

[0046] In one embodiment of the present invention, during the synthesis of compound 7, p-hydroxymethylbenzaldehyde 6 is dehydrated and condensed with compound 5 to generate hydroxymethylbenzylamine derivative 7, and then the amino group is protected with benzyloxycarbonyl to obtain compound 8; compound 8 is esterified with phthalic anhydride to obtain linker compound 9; it is linked with the solid support Merrifield resin to obtain resin 10, and then the tert-butyldimethylsilyl group is removed to obtain the final linker system ②.

[0047] In one embodiment of the present invention, during the synthesis of compound 7, the molar ratio of compound 5 to p-hydroxymethylbenzaldehyde is 1.1:1.

[0048] In one embodiment of the present invention, during the synthesis of compound 7, the molar ratio of sodium borohydride to p-hydroxymethylbenzaldehyde is 1.05:1.

[0049] In one embodiment of the present invention, anhydrous sodium sulfate is added as a desiccant during the synthesis of compound 7.

[0050] In one embodiment of the present invention, during the synthesis of compound 7, the solvent is tetrahydrofuran, and the reaction is carried out overnight (8-16 h) at room temperature. Then the solvent is replaced with ethanol, and the reaction is carried out with sodium borohydride for 4 hours at a temperature of 0°C to room temperature.

[0051] In one embodiment of the present invention, during the synthesis of compound 8 from compound 7, the molar ratio of benzyloxycarbonyl chloride to the aforementioned compound 6 is 5.4:1.

[0052] In one embodiment of the present invention, during the synthesis of compound 8 from compound 7, the reaction solvent is methanol, the reaction conditions are room temperature, and the reaction time is 3 hours.

[0053] In one embodiment of the present invention, during the synthesis of compound 9 from compound 8, the molar ratio of compound 8 to phthalic anhydride is 1:2.

[0054] In one embodiment of the present invention, during the synthesis of compound 9 from compound 8, the molar ratio of compound 8 to 4-dimethylaminopyridine is 1:1.

[0055] In one embodiment of the present invention, during the synthesis of compound 9 from compound 8, dichloromethane is used as the solvent, the reaction conditions are room temperature, and the reaction time is 3 hours.

[0056] In one embodiment of the present invention, the method for synthesizing resin 10 is the same as the method for synthesizing resin 3.

[0057] In one embodiment of the present invention, during the synthesis of compound 10 from compound 9, the molar ratio of compound 9 to Merrifield resin is 1:0.5; the molar ratio of cesium carbonate to compound 9 is 1.5:1; the molar ratio of tetrabutylammonium iodide to compound 9 is 0.5:1; the solvent is N,N-dimethylformamide; the reaction temperature is 60°C; and the reaction is carried out with shaking for 24 hours.

[0058] In one embodiment of the present invention, the synthesis of resin 10 to connecting arm system ② is the same as the synthesis method of resin 3 to connecting arm system ①.

[0059] In one embodiment of the present invention, the connecting arm system ② was determined to have a loading of 0.61 mmol / g using the method described in An accurate method for the quantitation of Fmoc-derivatized solid phase supports. Gude, M. Letters in Peptide Science 9, 203-206 (2002).

[0060] In one embodiment of the invention, the linker system ③ has an alkyl ester core, a 6-hydroxyhexanoic acid linker (here the ester core and linker are the same), and a solid support, Merrifield resin. After synthesizing the polysaccharide and cleaving the linker, a five-carbon-linked carboxyl group is retained at the reduced end of the polysaccharide.

[0061] This invention also provides a method for synthesizing the connecting arm system ③, and the corresponding synthesis route is shown below:

[0062]

[0063] In one embodiment of the present invention, in the synthesis method of the connecting arm system ③, the molar ratio of compound 12 to Merrifield resin is 1:0.5.

[0064] In one embodiment of the present invention, in the synthesis method of the connecting arm system ③, the molar ratio of cesium carbonate to compound 2 is 1.5:1.

[0065] In one embodiment of the present invention, in the synthesis method of the connecting arm system ③, the molar ratio of tetrabutylammonium iodide to compound 2 is 0.5:1.

[0066] In one embodiment of the present invention, the solvent is N,N-dimethylformamide, the reaction temperature is 60°C, and the reaction is carried out by shaking for 24 hours.

[0067] In one embodiment of the present invention, the connecting arm system ③ was measured to have a loading of 0.84 mmol / g using the method described in An accurate method for the quantitation of Fmoc-derivatized solid phase supports. Gude, M. Letters in Peptide Science 9, 203-206 (2002).

[0068] The present invention also provides a method for solid-phase synthesis of polysaccharides using the above-mentioned basic sensitive linker system, comprising solid-phase synthesis with any one or more of the following monosaccharide building blocks as raw materials and basic sensitive linker system: β(1-4) linked glucose (14), α(1-4) linked glucose (15), β(1-3) linked glucose (16), α(1-6) linked mannose (17);

[0069] The corresponding monosaccharide building block structure is as follows:

[0070]

[0071] In one embodiment of the present invention, α(1-6)mannose building blocks were synthesized in the solid phase using three connecting arm systems to obtain three tetrasaccharides with different terminal structures, the tetrasaccharide structures of which are shown below:

[0072]

[0073]

[0074] In one embodiment of the present invention, α(1-4) glucose building blocks are synthesized in the solid phase using connecting arm system ① and connecting arm system ②, respectively, to obtain tetrasaccharides with two different end modifications; the structures of the two tetrasaccharides are shown below:

[0075]

[0076] In one embodiment of the present invention, β(1-4) glucose building blocks are synthesized in the solid phase using connecting arm system ① and connecting arm system ②, respectively, to obtain tetrasaccharides with two different end modifications; the structures of the two tetrasaccharides are shown below:

[0077]

[0078] In one embodiment of the present invention, β(1-3) glucose building blocks are synthesized in the solid phase using connecting arm system ① and connecting arm system ②, respectively, to obtain tetrasaccharides with two different end modifications; the structures of the two tetrasaccharides are shown below:

[0079]

[0080] In one embodiment of the present invention, the solid-phase synthesis process specifically includes:

[0081] (1) The connecting arm system was subjected to a glycosylation reaction with the monosaccharide building block. After the reaction was completed, the resin was filtered out and washed.

[0082] (2) The resin after glycosylation reaction is swollen in a triethylamine N,N-dimethylformamide solution to remove the 9-fluorenylmethoxycarbonyl (Fmoc group);

[0083] (3) After removing the 9-fluorenylmethoxycarbonyl group, filter, wash and dry the resin, then soak the resin in an acid solution of a certain concentration.

[0084] (4) The above three-step reaction was repeated multiple times. Finally, the linker was cleaved using sodium methoxide solution and purified to obtain the corresponding polysaccharide.

[0085] In one embodiment of the present invention, the cycle is repeated 4 times to obtain the tetrasaccharide target.

[0086] The present invention also provides two fully deprotected free polysaccharides, including mannan 27 having a free amino group linked to a 5-carbon terminal at the reducing end, and mannan 28 having a free carboxyl group linked to a 5-carbon terminal at the reducing end.

[0087]

[0088] In one embodiment of the present invention, the benzyl deprotection process involves dissolving the obtained semi-protected polysaccharide in a mixed solution of ethyl acetate, tert-butanol, and water, adding three times the weight of the polysaccharide on carbon (10% Pd / C), stirring the reaction at room temperature for three days under hydrogen protection, filtering to remove the carbon on carbon, washing repeatedly with water, and concentrating and purifying the resulting mixture to obtain the corresponding fully deprotected tetrasaccharide.

[0089] Beneficial effects:

[0090] This invention utilizes a chemical synthesis method to conveniently, rapidly, and in high yield synthesize three basic-sensitive linker systems with different structures, applicable to the synthesis of various polysaccharides. This invention synthesizes four different tetrasaccharides using the linker system and performs complete deprotection of two mannose tetrasaccharides. The three linker systems are easily cleaved, and during cleavage, ester protecting groups of the polysaccharides can be removed, simplifying subsequent deprotection steps.

[0091] Using the connecting arm system ②③ of this invention, the synthesized glycans with amino and carboxyl group modifications at their ends can be conveniently applied to the development of glycobiology research tools, such as the preparation of glycochips, the construction of protein-glycan conjugates, and the synthesis of glycosyl-modified functional materials. Mannose receptors are present on the surface of macrophages and dendritic cells, playing a crucial role in pathogen recognition and antigen presentation. The modified mannose synthesized in this invention can be conveniently modified onto the surface of drug delivery materials (e.g., liposomes) via amide bond coupling, improving the targeting of the delivery system and enhancing drug therapeutic efficacy.

[0092] The α(1-6)mannan involved in this invention is widely present in the structure of fungal N-linked glycoproteins, while β(1-3)glucan is one of the core components of the fungal cell wall. By modifying the ends of the glycans to prepare corresponding glycochips, they can be used for the screening and discovery of lectins; by coupling the modified glycans with carrier proteins to obtain antigens, they can be used for the development of fungal glycan antibodies. These tools are of great significance for the study of fungal glycobiology and the development of diagnostic and therapeutic methods for pathogenic fungi.

[0093] The molecules synthesized via the linker arm system ① can be deprotected to yield unmodified natural glycans. α(1-4)glucan has a natural starch structure, while β(1-4)glucan has a natural cellulose structure. The precise chemical structures of starch and cellulose oligosaccharides offer significant advantages in studying their molecular assembly behavior and structure-function relationships. Furthermore, the natural glucan molecules prepared using this invention can also be used to study the enzymatic reaction kinetics and substrate preference of glycosidases. Attached Figure Description

[0094] Figure 1 This is a schematic diagram of the base-cutting linker structure used in the solid-phase synthesis of polysaccharides according to the present invention, and a schematic diagram of solid-phase synthesis of tetrasaccharides. Detailed Implementation

[0095] To facilitate understanding of this invention, a more detailed description will follow. The instruments and reagents used, without specifying manufacturers, are all commercially available, conventional products.

[0096] The preparation of compound 1* was carried out according to the literature Synthesis of Heterosubstituted Hexaarylbenzenes via Asymmetric Carbonylative Couplings of Benzyl Halides. Potter, RG & Hughes, TSOrr. Lett. 9, 1187-1190 (2007). The specific process included: using terephthalic acid as a raw material, reacting it with tert-butyldimethylchlorosilane in tetrahydrofuran at room temperature overnight under the condition of imidazole as a promoter, and then obtaining it by column chromatography.

[0097] Compound 5*: Prepared according to the literature, referring to De-novo designed β-lysine derivatives can both augment and diminish the proliferation rates of E. coli through the action of Elongation Factor P.McDonnell,CM,Ghanim,M.,Southern,JM,Kelly,VP&Connon,SJBioorg.Med.Chem.Lett.59,128545(2022). The specific process includes: starting with 5-amino-1-pentanol, reacting with tert-butyldimethylchlorosilane in dichloromethane at room temperature for 5 hours with imidazole as a promoter, followed by purification by column chromatography.

[0098] Compound 6* is available from Shanghai Titan Technology Co., Ltd. Compound 12* is available from Shanghai Titan Technology Co., Ltd.

[0099] Example 1:

[0100] Synthesis of connecting arm system ①

[0101] Starting with compound 1*, compound 1* was esterified with phthalic anhydride to give compound 2*, with a yield of 66%. Compound 2* was linked with Merrifield resin to give compound 3*; the tert-butyldimethylsilyl protecting group of the compound was removed to obtain a basic-sensitive linker system ①.

[0102] Specific experimental procedures and steps:

[0103]

[0104] Compound 2*: Compound 1* (1 g, 3.96 mmol) was dissolved in 25 mL of dichloromethane, and 4-dimethylaminopyridine (48.2 mg, 3.96 mmol) was added, followed by the slow addition of phthalic anhydride (1.17 g, 7.92 mmol). The mixture was stirred at room temperature for 3 hours. After the reaction was complete, the reaction solution was extracted with water, the organic phase was collected and dried over anhydrous sodium sulfate. The solution was concentrated under reduced pressure and purified by column chromatography (petroleum ether / ethyl acetate = 6:1) to give the target compound 2* (1.04 g, 66%). 1 H NMR(400MHz,Chloroform-d)δ7.97-7.90(dd,1H),7.78-7.72(dd,1H),7.61(m,J=7.5,5.8Hz,2H), 7.41(d,J=8.1Hz,2H),7.33(d,J=7.9Hz,2H),5.37(s,2H),4.72(s,2H),0.95(s,9H),0.10(s,6H). 13 C NMR(151MHz,Chloroform-d)δ171.01,167.99,141.77,133.81,132.99,132.12,13 1.02,130.14,130.03,128.98,128.57,126.27,67.75,64.67,25.94,18.41,-5.27.

[0105]

[0106] Compound 3*: Merrifield resin (100-200 mesh, initial loading 1 mmol / g, 3.74 g, 3.74 mmol) was fully swollen in tetrahydrofuran. Cesium carbonate (3.66 g, 11.23 mmol) and tetrabutylammonium iodide (1.38 g, 3.74 mmol) were added, followed by Compound 2 (3 g, 7.48 mmol) dissolved in 60 mL of N,N-dimethylformamide. The reaction mixture was shaken at 60 °C for 24 hours. The mixture was filtered, and the resin was washed sequentially with 20 mL of tetrahydrofuran, water, tetrahydrofuran, N,N-dimethylformamide, methanol, and dichloromethane. The solvent was removed under reduced pressure. The dried resin was swollen in N,N-dimethylformamide, and cesium acetate (2.16 g, 11.23 mmol) was added. The mixture was shaken at 60 °C for 24 hours. The reaction solution was filtered and the resin was washed sequentially with 20 mL of tetrahydrofuran, water, tetrahydrofuran, N,N-dimethylformamide, methanol, and dichloromethane. The solvent was removed under reduced pressure and the resin was dried.

[0107]

[0108] Connecting arm system ①: Resin 3* was swollen in tetrahydrofuran, and a tetrahydrofuran solution of tetrabutylamine fluoride (1 mmol / mL, 3.8 mL, 3.75 mmol) was added. The mixture was shaken overnight at room temperature. The suspension was filtered and the resin was washed sequentially with 20 mL of tetrahydrofuran, water, tetrahydrofuran, N,N-dimethylformamide, methanol, and dichloromethane. The solvent was removed under reduced pressure, and the resin was dried.

[0109] The resulting connecting arm system① was tested using an accurate method for the quantitation of Fmoc-derivatized solid phase supports. Gude, M. Letters in Peptide Science 9, 203-206 (2002). The loading was determined to be 0.63 mmol / g using the method mentioned in the literature.

[0110] In this invention, the loading amount refers to the ratio of the amount of active components at all sites on the resin capable of carrying out the target reaction to the weight of the resin.

[0111] Example 2:

[0112] Synthesis of connecting arm system ②:

[0113] Compounds 5* and 6* were reductively amination of p-hydroxymethylbenzaldehyde, followed by protection of the amino group with a benzyloxycarbonyl group to yield compound 8*, with a two-step yield of 51%. Compound 8* was then esterified with phthalic anhydride to give compound 9*, with a yield of 86%. Compound 9* was then linked with Merrifield resin to give compound 10*. Removal of the tert-butyldimethylsilyl group from the compound yielded a basic-sensitive linker system ②.

[0114] Specific experimental procedures and steps:

[0115]

[0116] Compound 8*: Compound 5* (8 g, 36.79 mmol), p-hydroxymethylbenzaldehyde 6* (4.96 g, 36.43 mmol), and anhydrous sodium sulfate (10.4 g, 72.86 mmol) were added to tetrahydrofuran and stirred at room temperature for 16 hours. The solvent was removed under reduced pressure. The crude product was dissolved in 100 mL of ethanol, kept in an ice bath, and NaBH4 (1.45 g, 38.25 mmol) was slowly added. After stirring until homogeneous, the mixture was brought to room temperature. After the reaction was complete, the reaction was quenched with 5 mL of acetone. The solvent was removed under reduced pressure to obtain the crude product of compound 7*.

[0117] The crude product of compound 7* was dissolved in 250 mL of methanol, and triethylamine (32.4 mL, 233.2 mmol) and benzyl chloroformate (benzyloxycarbonyl chloride, 28.3 mL, 196.7 mmol) were added. The reaction was carried out at room temperature for 5 hours, and the reaction was quenched by adding 10 g of potassium carbonate and stirring for 1 hour. The solvent was removed under reduced pressure, and the crude product was extracted with dichloromethane and water. The organic phase was collected and dried over anhydrous sodium sulfate. The purified compound 8* (8.79 g, 51%) was obtained by column chromatography. 1 H NMR(400MHz,Chloroform-d)δ7.45-7.22(m,8H),7.18(d,J=7.8Hz,1H),5.23-5.15(d,2H),4.69(s,2H),4.51(s,2H),3.61-3. 52(m,2H),3.24(dt,J=23.7,7.6Hz,2H),2.03(s,1H),1.63-1.45(m,4H),1.30(q,J=7.8,7.3Hz,2H),0.91(s,9H),0.06(s,6H). 13CNMR(101MHz,Chloroform-d)δ156.77,156.18,140.07,137.37,136.83,128.46,128.03,127.94,127.83,127. 45,127.22,67.19,65.01,63.00,50.25,49.95,47.17,46.29,32.50,27.95,27.54,25.98,23.08,18.36,-5.27.

[0118]

[0119] Compound 9*: Compound 8* (8.79 g, 18.44 mmol) was dissolved in 150 mL of dichloromethane, and 4-dimethylaminopyridine (2.25 g, 18.44 mmol) and phthalic anhydride (5.46 g, 36.89 mmol) were added. The reaction mixture was stirred at room temperature for 3 hours. The reaction mixture was extracted with water, and the organic phase was collected and dried over anhydrous sodium sulfate. Compound 9* (9.92 g, 86%) was purified by column chromatography. 1 H NMR(400MHz,Chloroform-d)δ7.95-7.88(d,1H),7.76-7.68(dd,1H),7.65-7.54(m,2H),7.42-7.24(m,8H),7.18(d,J=7.7Hz,1H),5.35(s,2H),5.18( d,J=13.6Hz,2H),4.48(d,J=9.9Hz,2H),3.57(m,J=10.5,4.2Hz,2H),3.29- 3.19(m,2H),1.50(s,4H),1.27(d,J=7.5Hz,2H),0.90(s,9H),0.05(s,6H). 13 CNMR(101MHz,Chloroform-d)δ170.67,167.98,156.80,138.30,136.75,134.41,133.04,132.00,130.96,130.36,129.92,128.86,128.78, 128.45,127.95,127.85,127.45,67.47,67.26,63.09,53.42,50.44,5 0.08,47.39,46.62,32.44,28.01,27.60,25.98,23.05,18.37,-5.27.

[0120]

[0121] Compound 10*: The procedure for converting compound 9* to compound 10* is the same as that for converting compound 2* to compound 3*.

[0122]

[0123] Connecting arm system ②: The procedure for connecting compound 10* to connecting arm system ② is the same as that for connecting compound 3* to compound 4*.

[0124] The resulting connecting arm system ② was tested using an accurate method for the quantitation of Fmoc-derivatized solid phase supports. Gude, M. Letters in Peptide Science 9, 203-206 (2002). The loading was determined to be 0.61 mmol / g using the method mentioned in the literature.

[0125] Example 3:

[0126] Synthesis of connecting arm system ③:

[0127] By connecting compound 12* to Merrifield resin, a connecting arm system ③ can be obtained.

[0128] Specific experimental procedures and steps:

[0129]

[0130] Connecting arm system ③: The operation steps of compound 12* to connecting arm system ③ are the same as those of compound 2* to compound 3*.

[0131] The resulting connecting arm system ③ was tested using an accurate method for the quantitation of Fmoc-derivatized solid phase supports. Gude, M. Letters in Peptide Science 9, 203-206 (2002). The loading was determined to be 0.84 mmol / g using the method mentioned in the literature.

[0132] Example 4:

[0133] Solid-phase synthesis of tetrasaccharides:

[0134] The linker system was glycosylated with the sugar building blocks. After the reaction, the resin was filtered out and washed. The resin was swollen in a triethylamine N,N-dimethylformamide solution to remove the 9-fluorenylmethoxycarbonyl group. After filtration, washing, and drying, the resin was soaked in an acid solution of a certain concentration. The three-step reaction was repeated four times. The linker was then cleaved with sodium methoxide solution, and the corresponding tetrasaccharide was obtained after purification.

[0135] Specific experimental procedures and steps:

[0136] (1) Glycosylation:

[0137] Glycosylation of α(1-6)mannose or α(1-4)glucose building blocks:

[0138] Dissolve α(1-6)mannose or α(1-4)glucose building blocks (6.5 eq) in 4 mL of anhydrous dichloromethane, add N-iodosuccinimide (9.75 eq) and the linker system (100 mg, with the loading of the synthesized linker system being 1 eq), and add... Molecular sieves were used, and the system was replaced with argon gas. The reaction solution was cooled to -15°C and maintained for 30 minutes. Trifluoromethanesulfonic acid (1.3 eq) was added to the reaction system as a catalyst, and the reaction temperature was maintained at -15°C for 5 minutes, then raised to 0°C and reacted for 20 minutes. The suspension was filtered, the solid was collected, and washed sequentially with methanol, water, N,N-dimethylformamide, tetrahydrofuran, and dichloromethane. After drying, oligosaccharide conjugated resin was obtained.

[0139] Glycosylation of β(1-3)glucose or β(1-4)glucose building blocks:

[0140] Dissolve 6.5 eq of β(1-3)glucose or β(1-4)glucose building blocks in 4 mL of anhydrous dichloromethane, add the connecting arm system (1 eq), and add... Molecular sieves were used, and the system was replaced with argon gas. The reaction solution was cooled to -30°C and maintained for 30 minutes. The catalyst, trimethylsilyl trifluoromethanesulfonate (7.8 eq), was added to the reaction system, and the reaction temperature was maintained at -30°C for 5 minutes, then increased to -15°C and reacted for 25 minutes. The suspension was filtered, the solid was collected, and washed sequentially with methanol, water, N,N-dimethylformamide, tetrahydrofuran, and dichloromethane. After drying, the oligosaccharide conjugated resin was obtained.

[0141] Removal of the 9-fluorenemethoxycarbonyl group: The obtained oligosaccharide-conjugated resin was washed three times with 10 mL of N,N-dimethylformamide, suspended in 4 mL of 20% triethylamine in N,N-dimethylformamide solution, shaken for 30 minutes, and filtered to remove excess solvent. This process was repeated three times. The suspension was filtered, and the resin was washed sequentially with methanol, water, N,N-dimethylformamide, tetrahydrofuran, and dichloromethane, and dried to obtain an oligosaccharide-conjugated resin with one free hydroxyl group.

[0142] Acid washing: The oligosaccharide conjugated resin with one free hydroxyl group was swollen in 4 mL of anhydrous dichloromethane, and then... Molecular sieves were used, and the system was replaced with argon gas. The reaction solution was cooled to -20°C and maintained for 30 minutes. 40 μL of trimethylsilyl trifluoromethanesulfonate was added to the reaction system, and the reaction temperature was maintained at -20°C for 15 minutes. The suspension was filtered, and the resin was washed sequentially with methanol, water, N,N-dimethylformamide, tetrahydrofuran, and dichloromethane. The resin was then dried.

[0143] The above process was repeated three times with the resin obtained after acid washing to obtain disaccharide conjugated resin, trisaccharide conjugated resin, and tetrasaccharide conjugated resin in sequence.

[0144] (2) Alkali pyrolysis:

[0145] The obtained tetrasaccharide conjugated resin was swollen in 3 mL of tetrahydrofuran for 30 minutes, then 3 mL of methanol and 0.5 mL of sodium methoxide were added, and the mixture was stirred overnight. The reaction solution was neutralized to neutral using a cation exchange resin, filtered, and the resin was washed. The organic phase was collected, concentrated, and purified by HPLC to obtain the corresponding tetrasaccharide compound.

[0146] The yields of tetrasaccharide compound 18* were 20%; the yields of tetrasaccharide compound 19* were 29%; the yields of tetrasaccharide compound 20* were 23%; the yields of tetrasaccharide compound 21* were 9%; the yields of tetrasaccharide compound 22* were 17%; the yields of tetrasaccharide compound 23* were 21%; the yields of tetrasaccharide compound 24* were 19%; the yields of tetrasaccharide compound 25* were 40%; and the yields of tetrasaccharide compound 26* were 30%.

[0147] Example 5:

[0148] Benzyl deprotection:

[0149] The tetrasaccharides (compounds 18*-26* containing protecting groups) that required benzyl removal were dissolved in a mixed solution of ethyl acetate:tert-butanol:water = 1:2:1. Palladium on carbon (10% Pd / C) at 300% of the weight of the tetrasaccharide was added. The air in the system was replaced with hydrogen. The reaction was stirred at room temperature for 3 days under hydrogen protection. The reaction solution was filtered through a filter membrane. The filtered palladium on carbon was repeatedly washed with water. The mixture was collected, concentrated, and purified by HPLC to obtain the corresponding benzyl-deprotected tetrasaccharides.

[0150] Specifically, tetrasaccharide compound 27* is obtained by deprotecting tetrasaccharide compound 20*; tetrasaccharide compound 28* is obtained by deprotecting tetrasaccharide compound 19*.

[0151]

[0152] Compound 18*: 11H NMR (600 MHz, Chloroform-d) δ 7.39 - 7.12 (m, 42H), 7.09 (d, J = 7.6 Hz, 2H), 4.93 - 4.86 (m, 6H), 4.79 (d, J = 10.9 Hz, 1H), 4.69 (d, J = 10.9 Hz, 1H), 4.67 - 4.60 (m, 9H), 4.57 - 4.48 (m, 6H), 4.46 (d, J = 11.0 Hz, 1H), 4.34 (d, J = 12.0 Hz, 1H), 4.19 - 4.13 (t, 1H), 4.09 - 3.98 (t, 3H), 3.97 - 3.89 (m, 4H), 3.88 - 3.75 (m, 8H), 3.74 - 3.70 (m, 2H), 3.64 (m, J = 10.0, 2.7 Hz, 2H), 3.58 (t, J = 9.8 Hz, 2H), 3.51 (t, J = 9.7 Hz, 1H). 13 13C NMR (151 MHz, Chloroform-d) δ 141.39, 138.57, 138.36, 138.32, 138.13, 138.06, 138.03, 137.68, 134.92, 129.36, 128.62, 128.56, 128.48, 128.46, 128.43, 128.39, 128.37, 128.14, 128.07, 128.02, 127.98, 127.96, 127.93, 127.91, 127.87, 127.85, 127.80, 127.77, 127.75, 127.69, 127.66, 127.11, 99.62, 98.30, 97.11, 95.35, 80.31, 79.92, 79.66, 78.97, 75.51, 75.24, 75.21, 75.12, 74.99, 74.69, 73.84, 73.77, 72.09, 72.01, 71.99, 71.79, 71.60, 71.47, 70.75, 68.33, 68.31, 68.20, 68.02, 68.00, 67.52, 66.23, 65.52, 64.76, 61.91.

[0153]

[0154] Compound 19*: 11H NMR (600 MHz, Chloroform-d) δ 7.39 - 7.16 (m, 40H), 5.05 (d, J = 1.8 Hz, 1H), 4.99 (d, J = 1.7 Hz, 1H), 4.95 (d, 1H), 4.87 (dd, J = 11.1, 6.7 Hz, 3H), 4.84 (d, J = 1.5 Hz, 1H), 4.82 (d, J = 11.2 Hz, 1H), 4.72 - 4.57 (m, 9H), 4.53 - 4.45 (m, 3H), 4.13 (s, J = 2.4 Hz, 1H), 4.06 (d, J = 14.5, 3.2, 1.8 Hz, 2H), 4.01 (s, J = 3.3, 1.6 Hz, 1H), 3.91 - 3.78 (m, 7H), 3.75 - 3.53 (m, 14H), 3.35 (m, J = 9.7, 6.2 Hz, 1H), 2.23 (t, J = 7.4 Hz, 2H), 1.55 (m, J = 7.6 Hz, 2H), 1.52 - 1.45 (m, 2H), 1.37 - 1.28 (m, 2H). 13 13C NMR (151 MHz, Chloroform-d) δ 177.17, 138.47, 138.31, 138.28, 138.19, 138.05, 137.97, 137.82, 137.72, 128.58, 128.53, 128.50, 128.44, 128.39, 128.36, 128.02, 128.00, 127.95, 127.89, 127.84, 127.82, 127.80, 127.76, 127.73, 127.69, 127.62, 99.31, 98.85, 98.77, 98.36, 80.27, 79.85, 79.78, 79.38, 75.16, 74.99, 74.93, 74.48, 74.32, 74.00, 73.95, 71.92, 71.85, 71.79, 71.76, 70.60, 70.43, 69.75, 68.33, 68.09, 68.00, 67.97, 67.10, 66.06, 65.82, 65.63, 61.83, 33.60, 28.66, 25.44, 24.27.

[0155]

[0156] Compound 20*: 11H NMR (600 MHz, Chloroform-d) δ 7.35 - 7.18 (m, 49H), 5.16 (d, J = 14.2 Hz, 2H), 5.02 (s, J = 1.7 Hz, 1H), 4.96 - 4.92 (s, 2H), 4.90 - 4.81 (m, 4H), 4.74 (d, J = 11.6 Hz, 1H), 4.64 (m, J = 19.0, 12.7, 12.0 Hz, 11H), 4.52 - 4.42 (m, 5H), 4.11 (s, J = 2.3 Hz, 1H), 4.04 (s, J = 2.9 Hz, 2H), 3.94 (s, J = 6.7 Hz, 1H), 3.88 - 3.78 (m, 7H), 3.75 - 3.56 (m, 13H), 3.49 (m, J = 24.3, 8.6, 7.6 Hz, 1H), 3.18 (m, J = 35.7, 14.3, 7.4 Hz, 3H), 1.43 (m, J = 37.3, 14.5, 7.2 Hz, 4H), 1.19 (m, J = 39.7, 16.0, 8.8 Hz, 2H). 13 13C NMR (151 MHz, Chloroform-d) δ 140.21, 138.46, 138.35, 138.30, 138.20, 138.06, 137.97, 137.80, 137.73, 137.28, 128.60, 128.54, 128.51, 128.48, 128.44, 128.39, 128.36, 128.09, 128.04, 128.02, 127.98, 127.92, 127.90, 127.82, 127.79, 127.72, 127.70, 127.67, 127.61, 127.50, 127.21, 99.26, 99.02, 98.78, 98.69, 80.30, 79.97, 79.86, 79.54, 75.15, 74.97, 74.94, 74.38, 74.26, 74.12, 74.04, 71.96, 71.84, 71.81, 71.76, 70.63, 70.32, 69.98, 68.29, 68.11, 68.01, 67.98, 67.23, 66.09, 65.92, 65.64, 6%4.81, 62.00, 50.29, 47.34, 46.43, 28.84, 27.89, 27.41, 23.38.

[0157]

[0158] Compound 21*: 11H NMR (600 MHz, Methanol-d4) δ 7.47 - 7.45 (m, 2H), 7.43 (dt, J = 8.9, 3.0 Hz, 4H), 7.38 - 7.26 (m, 18H), 5.39 (d, J = 3.7 Hz, 1H), 5.34 (t, J = 4.0 Hz, 2H), 4.84 (d, J = 3.8 Hz, 1H), 4.84 - 4.76 (m, 5H), 4.67 (t, J = 11.8 Hz, 2H), 4.60 (s, 2H), 4.54 (d, J = 11.8 Hz, 1H), 4.46 (d, J = 12.1 Hz, 1H), 4.07 (t, J = 9.7, 8.3 Hz, 1H), 4.01 (td, J = 9.3, 4.3 Hz, 2H), 3.84 - 3.68 (m, 10H), 3.68 - 3.60 (m, 4H), 3.59 - 3.52 (m, 2H), 3.38 (m, J = 20.3, 10.0, 3.7 Hz, 4H), 3.28 (t, J = 9.4 Hz, 1H), 2.98 (s, J = 1.9 Hz, 1H), 2.85 (s, J = 1.0 Hz, 1H). 13 13C NMR (151 MHz, MeOD) δ 163.46, 141.03, 138.30, 137.77, 137.72, 137.67, 136.43, 128.41, 128.37, 128.33, 128.07, 128.04, 127.95, 127.88, 127.80, 127.69, 127.62, 127.39, 126.61, 98.64, 98.42, 98.09, 95.34, 79.45, 79.06, 78.85, 78.67, 77.98, 77.59, 73.29, 73.24, 73.18, 73.14, 73.11, 73.07, 73.03, 72.83, 72.36, 71.33, 71.26, 70.62, 70.32, 68.51, 63.57, 61.26, 60.67, 60.61, 35.54, 30.24.

[0159]

[0160] Compound 22*: α: 1H NMR(600MHz,Methanol-d4)δ7.48-7.38(m,8H),7.37-7.25(m,12H),5.38(d,J=3.7Hz,1H),5.34(t,J=4.0Hz,2H),4.86-4.76(m,6H),4.75-4.72(m,2H),4.61(d,J=11.9Hz,1H),4.02(t,J=9.4Hz,3H),3.83-3.69(m,10H),3.68-3.61(m,3H),3.61-3.53(m,4H),3.42-3.33(m,4H),3.32(m,J=7.8Hz,1H),3.27(t,J=9.4Hz,1H),2.25(t,J=7.4Hz,2H),1.61(m,J=7.1,2.9Hz,4H),1.45-1.37(m,2H). 13 CNMR(151MHz,MeOD)δ138.50,137.78,137.72,137.67,128.42,128.37,128.35,128.07,127.99,127.84,127.69,127.64,127.44,98.62,98.44,98.17,96.54,79.44,79.28,78.86,78.68,78.02,77.93,77.77,73.30,73.27,73.17,73.13,73.08,73.06,73.02,72.86,72.44,71.32,71.24,70.35,70.32,67.46,61.26,60.67,33.83,28.83,25.55,24.59.

[0161] β: 1 H NMR(600MHz,Methanol-d4)δ7.48-7.41(m,6H),7.39-7.24(m,14H),5.40(d,J=3.7Hz,1H),

[0162] 5.33 (dd, J = 3.8, 1.4 Hz, 2H), 4.87 - 4.76 (m, 8H), 4.74 (d, J = 11.4 Hz, 1H), 4.40 (d, J = 7.8 Hz, 1H), 4.00 (q, J = 9.8, 8.5 Hz, 2H), 3.93 (m, J = 9.6, 6.3 Hz, 1H), 3.84 - 3.69 (m, 10H), 3.67 - 3.59 (m, 3H), 3.58 - 3.50 (m, 3H), 3.42 - 3.33 (m, 4H), 3.29 - 3.25 (m, 1H), 3.17 (dd, J = 9.3, 7.8 Hz, 1H), 2.22 (t, J = 7.4 Hz, 2H), 1.65 - 1.56 (m, 4H), 1.48 - 1.36 (m, J = 7.7, 7.2 Hz, 2H). 13 C NMR (151 MHz, MeOD) δ 138.80, 137.76, 137.71, 137.67, 128.42, 128.37, 128.36, 128.07, 128.05, 127.79, 127.68, 127.63, 127.56, 127.10, 102.96, 98.76, 98.56, 96.22, 81.28, 79.47, 78.87, 78.71, 76.49, 74.82, 73.96, 73.35, 73.29, 73.22, 73.12, 73.05, 72.94, 71.34, 71.25, 70.31, 69.18, 61.25, 60.74, 60.65, 46.05, 29.19, 25.57, 24.67, 15.87, -1.45.

[0163]

[0164] Compound 23*: 11H NMR (600 MHz, Chloroform-d) δ 7.39 - 7.30 (m, 11H), 7.30 - 7.19 (m, 33H), 4.94 - 4.79 (m, 8H), 4.74 (d, J = 11.5 Hz, 1H), 4.65 (t, J = 6.4 Hz, 3H), 4.60 (d, J = 11.8 Hz, 1H), 4.58 - 4.53 (m, 3H), 4.51 (d, J = 7.7 Hz, 1H), 4.48 (d, J = 8.5 Hz, 1H), 4.46 (d, J = 8.4 Hz, 1H), 4.41 - 4.36 (m, 4H), 4.33 (d, J = 7.5 Hz, 1H), 3.99 (t, J = 9.1 Hz, 1H), 3.96 - 3.86 (m, 3H), 3.77 (dd, J = 11.6, 2.2 Hz, 1H), 3.63 (m, 2H), 3.60 - 3.51 (m, 3H), 3.48 - 3.32 (m, 10H), 3.23 (t, J = 9.0 Hz, 1H), 3.15 (m, 3H). 13 13C NMR (151 MHz, CDCl3) δ 171.20, 140.72, 139.19, 139.17, 139.00, 138.79, 137.78, 137.59, 137.40, 137.38, 136.52, 128.49, 128.44, 128.38, 128.35, 128.24, 128.15, 128.11, 128.02, 128.01, 127.99, 127.90, 127.86, 127.76, 127.71, 127.69, 127.40, 127.31, 127.30, 127.20, 127.12, 126.96, 126.83, 103.52, 103.41, 103.24, 101.77, 83.53, 83.51, 83.37, 77.26, 77.05, 76.84, 76.69, 75.54, 75.38, 75.07, 74.63, 74.58, 74.45, 74.43, 74.39, 74.37, 74.32, 73.74, 73.65, 73.61, 73.58, 73.52, 71.75, 70.76, 70.51, 68.65, 68.57, 65.04, 60.43, 29.72, 21.07, 14.22, 0.02.

[0165]

[0166] Compound 24*: 11H NMR (600 MHz, Chloroform-d) δ 7.36 - 7.18 (m, 40H), 4.92 - 4.79 (m, 6H), 4.74 (d, J = 11.5 Hz, 1H), 4.65 (d, J = 12.0 Hz, 1H), 4.58 - 4.53 (m, 3H), 4.51 (d, J = 7.7 Hz, 1H), 4.48 (d, J = 8.2 Hz, 1H), 4.46 (d, J = 8.3 Hz, 1H), 4.41 - 4.35 (m, 4H), 4.22 (d, J = 7.6 Hz, 1H), 3.96 (t, J = 9.2 Hz, 1H), 3.93 - 3.86 (m, 4H), 3.76 (dd, J = 11.6, 2.3 Hz, 1H), 3.62 (m, 2H), 3.57 - 3.38 (m, 12H), 3.34 (m, 3H), 3.23 (t, J = 9.0 Hz, 1H), 3.19 - 3.09 (m, 3H), 2.33 (t, J = 7.4 Hz, 2H), 1.64 (m, 4H), 1.41 (m, 2H). 13 13C NMR (151 MHz, Chloroform-d) δ 178.18, 139.19, 139.16, 139.03, 138.75, 137.77, 137.51, 137.36, 128.50, 128.43, 128.39, 128.35, 128.24, 128.12, 128.05, 128.01, 127.90, 127.87, 127.78, 127.71, 127.70, 127.39, 127.30, 127.19, 126.94, 126.80, 103.57, 103.47, 103.27, 102.85, 83.52, 83.48, 83.38, 76.69, 75.57, 75.43, 75.09, 74.59, 74.47, 74.43, 74.40, 74.38, 74.32, 74.29, 73.73, 73.64, 73.61, 73.58, 73.52, 71.71, 70.47, 69.58, 68.74, 68.61, 68.56, 33.63, 29.73, 29.09, 25.42, 24.29.

[0167]

[0168] Compound 25*: 11H NMR (600 MHz, Chloroform-d) δ 7.36 - 7.28 (m, 8H), 7.28 - 7.13 (m, 36H), 6.08 (s, 1H), 5.96 (s, 1H), 5.13 - 5.06 (m, 3H), 4.93 (d, J = 12.0 Hz, 1H), 4.79 (d, J = 11.1 Hz, 1H), 4.76 (s, J = 4.1 Hz, 2H), 4.63 - 4.40 (m, 13H), 4.35 (d, J = 7.7 Hz, 1H), 4.28 - 4.21 (m, 3H), 3.73 - 3.47 (m, 15H), 3.45 - 3.24 (m, 7H). 13 13C NMR (151 MHz, Chloroform-d) δ 141.01, 138.72, 138.70, 138.65, 138.32, 138.13, 138.05, 138.00, 136.38, 128.48, 128.41, 128.35, 128.33, 128.32, 128.26, 128.22, 128.21, 128.06, 127.91, 127.82, 127.�8, 127.77, 127.67, 127.62, 127.59, 127.57, 127.53, 127.44, 127.42, 127.39, 127.08, 105.77, 105.50, 105.39, 100.95, 88.15, 87.70, 87.31, 76.74, 76.06, 75.87, 75.39, 75.29, 75.27, 75.24, 75.08, 75.06, 74.75, 74.58, 74.55, 73.59, 73.47, 73.39, 73.34, 73.32, 70.66, 68.85, 68.42, 68.25, 68.19, 64.76.

[0169]

[0170] Compound 26*: 11H NMR (600 MHz, Chloroform-d) δ 7.33 - 7.12 (m, 40H), 5.13 - 5.06 (m, 3H), 4.77 - 4.75 (m, 1H), 4.59 - 4.41 (m, 12H), 4.31 (dd, J = 12.1, 8.8 Hz, 1H), 4.29 - 4.23 (m, 3H), 3.93 (m, 1H), 3.76 - 3.42 (m, 21H), 3.39 (m, 3H), 3.33 - 3.29 (m, 4H), 2.31 (t, J = 7.4 Hz, 2H), 1.71 - 1.59 (m, 4H), 1.48 - 1.35 (m, 2H). 13 13C NMR (151 MHz, Chloroform-d) δ 174.46, 138.67, 138.56, 138.29, 138.05, 138.01, 128.50, 128.48, 128.37, 128.32, 128.30, 128.25, 128.21, 128.03, 127.91, 127.87, 127.76, 127.74, 127.65, 127.62, 127.60, 127.56, 127.49, 127.48, 127.45, 127.41, 127.39, 105.81, 105.61, 105.32, 105.19, 102.31, 87.80, 87.68, 86.74, 76.11, 75.43, 75.39, 75.06, 75.00, 74.94, 74.87, 74.64, 74.59, 73.71, 73.46, 73.41, 73.39, 73.33, 73.30, 69.65, 68.84, 68.38, 68.20, 51.63, 33.87, 28.96, 25.47, 24.43.

[0171]

[0172] Compound 27*: 1 1H NMR (400 MHz, Deuterium Oxide) δ 4.83 (s, 1H), 4.81 (d, J = 2.4 Hz, 2H), 4.77 (s, 1H), 3.93 - 3.81 (m, 7H), 3.81 - 3.53 (m, 18H), 3.52 - 3.44 (m, 1H), 2.92 (t, J = 7.6 Hz, 2H), 1.67 - 1.52 (m, 4H), 1.45 - 1.28 (m, J = 6.8 Hz, 2H). 13C NMR(151MHz,DeuteriumOxide)δ170.96,99.90,99.41,99.27,72.72,70.92,70.79,70.77,70.72,70.68,7 0.55,70.06,69.98,69.94,67.63,66.75,66.62,66.59,66.57,65.57,60.93,39.37,28.03,26.56,22.54.

[0173]

[0174] Compound 28*: 1H NMR (600MHz, Deuterium Oxide)δ4.76(d,J=1.7Hz,1H),4.74(d,J=1.7Hz,1H),4.73(d,J=1.6Hz,1H),4.70(d,J=1.7Hz,1H),3.83(dq,J=3.9,1.9Hz,3H),3.80-3. 76(m,4H),3.75-3.53(m,17H),3.50(t,J=9.7Hz,1H),3.41(dt,J=9.7,6.0Hz,1H),2.23(t,J=7.4Hz,2H),1.56-1.42(m,4H),1.25(m,2H). 13 C NMR(151MHz,DeuteriumOxide)δ179.52,99.87,99.46,99.27,99.24,72.70,70.88,70.82,70.74,70.70,70.62,70.53,7 0.09,69.98,69.96,69.92,67.74,66.73,66.63,66.61,66.59,65.63,65.58,65.51,60.92,34.09,28.14,24.99,24.14.

[0175] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A base-sensitive linker system, characterized in that, The system comprises an ester core, a linker, and a solid support; one end of the ester core is linked to the solid support, and the other end is connected to the linker; one end of the linker is connected to the ester core, and the other end contains exposed hydroxyl groups. The structure is shown below: , .

2. The alkaline-sensitive connecting arm system according to claim 1, characterized in that, The solid support is Merrifield resin.

3. The alkaline-sensitive connecting arm system according to claim 1, characterized in that, The method for synthesizing the connecting arm system ① includes the following steps: (1) One hydroxyl group of terephthalic acid was protected with a tert-butyldimethylsilyl protecting group to obtain compound 1; then it was esterified with phthalic anhydride to obtain compound 2; the synthetic route is shown below: (2) Compound 2 was linked to Merrifield resin to obtain compound 3; the synthetic route is shown below: (3) Remove the tert-butyldimethylsilyl protecting group of compound 3 to obtain the basic sensitive linker system ①.

4. The alkaline-sensitive connecting arm system according to claim 1, characterized in that, The method for synthesizing the connecting arm system ② includes the following steps: (1) Compound 5 and compound 6 were coupled by reductive amination, and then the amino group was protected with benzyloxycarbonyl to obtain compound 8; the synthetic route is shown below: (2) Compound 8 was reacted with phthalic anhydride via esterification to obtain compound 9; the synthetic route is shown below: (3) Compound 9 was linked to Merrifield resin to obtain compound 10; the synthetic route is shown below: (4) Remove the tert-butyldimethylsilyl protecting group of compound 10 to obtain the basic sensitive linker system ②.

5. The application of the basic-sensitive linker system according to any one of claims 1-4 in the solid-phase synthesis of polysaccharides.

6. A method for solid-phase synthesis of polysaccharides using the basic-sensitive linker system according to any one of claims 1-4, characterized in that, Including solid-phase synthesis using any one or more of the following monosaccharide building blocks as raw materials with an alkaline-sensitive linker system: β (1-4) linked glucose (14), α (1-4) linked glucose (15), β (1-3) linked glucose (16), α (1-6) linked mannose (17). The corresponding monosaccharide building block structure is as follows: 。 7. The method according to claim 6, characterized in that, The solid-phase synthesis process specifically includes: (1) The connecting arm system was subjected to a glycosylation reaction with the monosaccharide building block. After the reaction was completed, the resin was filtered out and washed. (2) The resin obtained in step (1) is swollen in a triethylamine N,N-dimethylformamide solution to remove the 9-fluorenylmethoxycarbonyl group; (3) After removing the 9-fluorenylmethoxycarbonyl group, filter and wash the resin to dry it, and then soak the resin in an acid solution; (4) The above three-step reaction was repeated multiple times. Finally, the linker was cleaved using sodium methoxide solution and purified to obtain the corresponding polysaccharide.

8. The method according to claim 7, characterized in that, The cycle was repeated 4 times, and the tetrasaccharide target was obtained accordingly.

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