A beta-1,3-glucan containing an o-6 side chain, methods of making and uses

Abstract

This invention discloses β-1,3-glucan containing an O-6 side chain, its preparation method, and its applications. Its structure is shown in Formula I: where R1, R2, R3, and R4 are each independently selected from any one of hydrogen, β-linked glucose, β-1,3-linked glucosylbiose, β-1,3-linked glucosyltriose, β-1,3-linked glucosyltetraose, β-1,6-linked glucosylbiose, β-1,6-linked glucosyltriose, β-1,6-linked glucosyltetraose, sulfonic acid group, and phosphate group. This invention also discloses a convergent synthetic route that can rapidly prepare the decasaccharide backbone of β-1,3-glucan in large quantities. Subsequently, a divergent synthetic approach is adopted, through strategic modification of the orthogonal protecting group in the decasaccharide backbone of β-1,3-glucan, to achieve tactical modification of the 6-position side chain, yielding the compound of Formula I.

Description

Technical Field

[0001] This invention relates to the field of dextran synthesis technology, specifically to a β-1,3-glucan containing an O-6 side chain, its preparation method, and its applications. Background Technology

[0002] β-1,3-glucan, a polysaccharide belonging to the natural carbohydrate family, has long attracted widespread attention in multiple disciplines such as biomedicine, food science, and materials engineering. This widespread attention stems from its diverse structures and significant biological activities, including immunomodulation, antibacterial and antiviral effects, antioxidant properties, and adjuvant cancer treatment. Its backbone structure is composed of unique β-1,3-glycosidic bonds, enabling it to specifically bind to specific receptors (such as Dectin-1) on the surface of immune cells in vivo. This interaction can activate immune signaling pathways, regulate the proliferation and activation of immune cells such as macrophages and lymphocytes, and ultimately enhance immune function. This natural immune-activating property makes β-1,3-glucan a promising candidate for the development of novel immunomodulators and adjuvants.

[0003] Structurally, β-1,3-glucans typically possess multiple 1,6-linked side chains, with specific structures varying depending on their origin. For example, lentinan from fungi contains two β-1,6-linked monoglucosyl branches per five main chain residues, while kelp polysaccharides from brown algae contain an average of one branch per seven residues. In contrast, yeast-derived β-1,3-glucans are modified with long β-1,6-linked glucosyl side chains. The biosynthesis of β-1,3-glucans involves multiple enzymes, resulting in highly heterogeneous mixtures of products isolated from natural sources, varying in main chain length, branching degree, and side chain type. Consequently, a deeper understanding of their immunological functions has been limited due to the lack of structurally well-defined β-glucan samples.

[0004] As one of the most structurally complex carbohydrates in nature, the chemical synthesis of β-1,3-glucan remains challenging. First, evidence suggests that synthesized β-1,3-glucan requires at least 10 sugar units to bind to the Dectin-1 receptor. Second, the O-6 side chain can exhibit diverse glucose syl patterns, showing variations in branching degree / spacing and side chain length / structure, further increasing the complexity of synthetic design. Numerous studies have focused on the synthesis of 1,3-glucans: Takahashi's group synthesized a hexadecyl sugar with a glucose side chain to investigate the interaction between glucan and its receptor Dectin-1; Seeberger's group prepared linear dodecyl sugars and branched tridecyl sugars using oligosaccharide solid-phase synthesis; Yang You's group synthesized linear hexadecyl sugars using gold-catalyzed glycosylation; Li Ming's group prepared a tridecyl sugar molecule containing a tetrasaccharide side chain; and recently, Li Zhongjun's group synthesized D-type β-1,3-octadecyl sugars and dodecyl sugars, as well as their corresponding L-configuration mirror isomers. However, these works mainly focus on altering the main chain length, while research on the synthesis of β-1,3-glucans with various O-6 side chains remains insufficient.

[0005] Therefore, it remains unclear which side chain structure provides optimal receptor binding capacity and whether a specific O-6 side chain pattern can enhance immunomodulatory activity. To address this deficiency, there is an urgent need to develop a library of β-1,3-glucan with diverse O-6 structures to elucidate their structure-activity relationships. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a β-1,3-glucan containing an O-6 side chain. β-1,3-glucan exhibits strong immunomodulatory activity, the intensity of which is related to the structure, number, and spacing of the O6 side chain.

[0007] A β-1,3-glucan containing an O-6 side chain has the structure shown in Formula I: , R1, R2, R3, and R4 are each independently selected from any one of hydrogen, β-linked glucose, β-1,3-linked glucosylbiose, β-1,3-linked glucosyltrisaccharide, β-1,3-linked glucosyltetrasaccharide, β-1,6-linked glucosylbiose, β-1,6-linked glucosyltrisaccharide, β-1,6-linked glucosyltetrasaccharide, sulfonic acid group, and phosphate group.

[0008] In this invention, the structures of β-linked glucose (A), β-1,3-linked glucosylbiose (B), β-1,3-linked glucosyltriose (C), β-1,3-linked glucosyltetraose (D), β-1,6-linked glucosylbiose (E), β-1,6-linked glucosyltriose (F), and β-1,6-linked glucosyltetraose (G) are shown below: .

[0009] Preferably, in the β-1,3-glucan containing the O-6 side chain, R1, R2, R3 and R4 are each independently selected from any one of hydrogen, β-linked glucose, β-1,3-linked glucosyltrisaccharide, β-1,6-linked glucosyltrisaccharide, and sulfonic acid group.

[0010] More preferably, the β-1,3-glucan containing the O-6 side chain is selected from any of the following structures: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0011] More preferably, the β-1,3-glucan containing the O-6 side chain is selected from any of the following structures: , , , , , , , , , , .

[0012] More preferably, the β-1,3-glucan containing the O-6 side chain is selected from any of the following structures: , , , .

[0013] The present invention also provides a method for preparing the above-mentioned β-1,3-glucan containing an O-6 side chain, comprising the following steps: (1) A one-pot glycosylation reaction was carried out using a trisaccharide trifluoroacetylimine ester donor, a tetrasaccharide acceptor containing an o-alkynyl benzoate group, and a reducing end trisaccharide acceptor to obtain the decasaccharide skeleton compound PBG-1; (2) Remove the orthogonal protecting group from the decasaccharide skeleton compound PBG-1, and then react it with the donor containing R1, R2, R3 or R4 substituents respectively. Finally, remove the various ester protecting groups under alkaline conditions and remove all benzyl protecting groups by hydrogenation to obtain β-1,3-glucan containing O-6 side chain. The structure of the decasaccharide skeleton compound PBG-1 is shown below: .

[0014] The specific reaction route is as follows: .

[0015] In this invention, a one-pot glycosylation reaction is first performed using a trisaccharide trifluoroacetylimine ester donor 1, a tetrasaccharide acceptor 2 containing an o-alkynyl benzoate group, and a reducing-terminal trisaccharide acceptor 3 to obtain the decasaccharide backbone PBG-1. It is worth noting that the four sites of the decasaccharide are equipped with orthogonal protecting groups: Fmoc, Troc, Alloc, and Lev. Any one of these protecting groups can be removed under specific conditions without affecting the other three.

[0016] Preferably, the preparation method of the trisaccharide trifluoroacetylimide ester donor 1 includes the following steps: trifluoroacetylimide ester (PTFAI) donor 4 undergoes a glycosylation reaction with an acceptor 5 containing a p-toluenethio group (STol) at the anodic position under TMSOTf catalysis to obtain trisaccharide 6; the levulinyl group (Lev) of trisaccharide 6 is removed under hydrazine acetate conditions and replaced with an Fmoc protecting group to obtain compound 7; compound 7 is hydrolyzed to a hemiacetal under trichloroisocyanuric acid (TCCA) conditions, and then reacted with trifluoroacetylimide chloride to prepare donor 1.

[0017] The specific route is as follows: .

[0018] Preferably, the method for preparing the tetrasaccharide receptor 2 containing an o-alkynyl benzoate group includes the following steps: a trifluoroacetylimine ester donor 8 and a receptor 5 containing a p-toluenethio (STol) group at the anodic position are reacted with TMSOTf catalysis to generate a tetrasaccharide 9. The anodic STol is hydrolyzed to a hemiacetal by TCCA and then reacted with o-alkynyl benzoic acid to prepare compound 10. After removing the Lev of the tetrasaccharide, it is converted into an Alloc protecting group. The non-reducing end TBS protecting group is removed using a pyridine hydrogen fluoride reagent to obtain the tetrasaccharide receptor 2 containing an o-alkynyl benzoate group.

[0019] The specific route is as follows: .

[0020] Preferably, the method for preparing the reduced-terminal trisaccharide receptor 3 includes the following steps: using a disaccharide trifluoroacetylimine ester donor 11, a 2+1 glycosylation reaction is carried out with a monosaccharide receptor 12 with a connector, and the resulting product is then treated with a pyridine fluoride reagent to obtain a reduced-terminal trisaccharide receptor 3 with a 3-hydroxyl exposed.

[0021] The specific route is as follows: .

[0022] The present invention also provides the application of the above-mentioned β-1,3-glucan containing O-6 side chain in the preparation of immunomodulators.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a series of β-1,3-glucans containing O-6 side chains and a convergent synthetic route for the rapid and large-scale preparation of the decasaccharide backbone of β-1,3-glucan. Subsequently, a divergent synthetic approach is employed, using strategic modification of the orthogonal protecting groups in the decasaccharide backbone of β-1,3-glucan to achieve tactical modification of the 6-position side chain, yielding compound I. Activity studies show that β-1,3-glucan possesses strong immunomodulatory activity, and the intensity of this activity is related to the structure, number, and spacing of the O-6 side chains. Attached Figure Description

[0024] Figure 1 The graphs show the statistical levels of macrophage cytokines expressed by compounds BG-1 to BG-31. In the graphs, A and B represent the levels of the cytokine TNF-α, and C and D represent the levels of IL-6.

[0025] Figure 2Statistical graph showing the phagocytic activity of compounds BG-8, BG-15, BG-19, BG-23~BG-25, and BG-27~BG-30 on macrophages.

[0026] Figure 3 This is a statistical graph showing the NK cell lysis rate of compounds BG-15, BG-19, BG-28, and BG-30. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0028] All raw materials used in this invention are commercially available.

[0029] Example 1 (1) Synthesis of trisaccharide trifluoroacetylimine ester donor 1

[0030] 6: Under an Ar atmosphere, trifluoroacetylimine ester donor 4 (1.96 g, 2.983 mmol), disaccharide acceptor 5 (2.53 g, 2.712 mmol), and 4 Å molecular sieve (1.42 g) were dissolved in dry dichloromethane (28.5 mL). After stirring at room temperature for 30 minutes, the mixture was cooled to -30 °C, and then TMSOTf (108 μL in 500 μL dry DCM) was added. The reaction was maintained at -30 °C until TLC showed that the reaction was almost complete. The reaction was quenched with saturated sodium bicarbonate solution, filtered, extracted three times with 30 mL of dichloromethane, and the organic phases were combined, washed with saturated sodium chloride solution, dried, evaporated to dryness, and column chromatography (PE / EA, 4:1) to give a white solid 6 (3.4274 g, 91%). 1 H NMR (600 MHz, Chloroform-d) δ 8.07 – 8.02 (m, 2H), 7.95 – 7.90 (m,2H), 7.72 – 7.69 (m, 2H), 7.67 (s, 1H), 7.57 – 7.51 (m, 6H), 7.48 (dd, J =7.5, 2.2 Hz, 2H), 7.41 – 7.34 (m, 7H), 7.31 – 7.27 (m, 4H), 7.23 (dd, J =10.1, 7.2 Hz, 4H), 7.18 – 7.15 (m, 2H), 7.04 (d, J = 7.9 Hz, 2H), 5.50 (d, J= 6.8 Hz, 2H), 5.24 (t, J = 8.6 Hz, 1H), 5.06 (d, J = 8.2 Hz, 1H), 4.99 (t, J = 4.4 Hz, 1H), 4.82 (d, J = 4.6 Hz, 1H), 4.75 – 4.67 (m, 2H), 4.57 (d, J =10.5 Hz, 1H), 4.28 (ddd, J = 10.4, 4.8, 2.7 Hz, 2H), 4.21 (dd, J = 9.5, 8.1Hz, 1H), 4.18 – 4.10 (m, 2H), 4.01 (dd, J = 7.5, 4.2 Hz, 1H), 3.88 (t, J =9.0 Hz, 1H), 3.72 (dd, J = 10.5, 8.0 Hz, 2H), 3.66 (td, J = 10.2, 4.8 Hz,2H), 3.61 – 3.55 (m, 2H), 3.47 – 3.40 (m, 2H), 3.15 (t, J = 9.5 Hz, 1H), 2.69– 2.60 (m, 2H), 2.52 (s, 2H), 2.30 (s, 3H), 2.14 (s, 3H), 0.66 (s, 9H), -0.10(s, 3H), -0.22 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 206.5, 172.5, 165.4, 165.0,164.5, 138.1, 138.1, 137.3, 137.1, 133.6, 133.3, 133.2, 132.6, 130.1, 130.0,129.73, 129.67, 129.3, 129.0, 128.8, 128.4, 128.33, 128.29, 128.1, 127.6,126.7, 126.2, 102.1, 101.9, 98.7, 97.1, 87.9, 81.9, 79.4, 78.7, 75.1, 75.0,74.6, 74.0, 73.4, 73.0, 72.8, 71.6, 70.6, 68.7, 68.6, 66.5, 64.3, 38.0, 29.9,27.9, 25.5, 21.1, 17.9, -4.3, -5.0; ESI-HRMS calcd for C 78 H 84 O 20 SSi[M+Na] + 1423.4938, found 1423.4903. 7: Compound 6 (3.00 g, 2.140 mmol) was dissolved in a mixed solvent of MeOH / DCM (22 mL, 1:1 / v:v), followed by the addition of AcOH (1.76 mL) and hydrazine hydrate (0.44 mL, 85% wt). The reaction was maintained at room temperature until the reaction was nearly complete as monitored by TLC. Acetone (2 mL) was added and stirred for 5 min, followed by quenching with saturated sodium bicarbonate solution. The mixture was extracted three times with 20 mL of DCM, and the organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain a white foamy solid. No further purification was required before proceeding to the next step.

[0031] The white foamy solid obtained in the previous step was dissolved in dry DCM (11 mL), and TMEDA (193 μL, 1.284 mmol) was added. FmocCl (664 mg, in 10 mL dry DCM) was added under ice bath conditions, and the addition was completed in 5 min. The reaction was maintained at 0 °C until TLC showed that the reaction was basically complete. The reaction was quenched with 1 M HCl. The mixture was extracted three times with 25 mL of DCM, and the organic phases were combined. The mixture was washed with saturated sodium bicarbonate solution and saturated sodium chloride solution, dried over anhydrous sodium sulfate, evaporated to dryness, and column chromatography was performed with PE / EA (8:1) to give white solid 7 (2.8629 g, 88% over 2 steps).1 H NMR (600 MHz, Chloroform-d) δ 8.17(d, J = 7.6 Hz, 2H), 7.99 (d, J = 7.6 Hz, 2H), 7.84 (m, 2H), 7.77 (m, 3H),7.71 – 7.55 (m, 10H), 7.45 (m, 9H), 7.41 – 7.36 (m, 6H), 7.34 – 7.30 (m, 4H),7.26 – 7.23 (m, 2H), 7.14 (d, J = 7.9 Hz, 2H), 5.60 (s, 1H), 5.55 (s, 1H),5.34 (s, 1H), 5.16 (d, J = 8.1 Hz, 1H), 5.08 (s, 1H), 4.95 (d, J = 4.4 Hz,1H), 4.82 (t, J = 9.3 Hz, 1H), 4.72 (d, J = 10.1 Hz, 1H), 4.65 (d, J = 10.6Hz, 1H), 4.49 (d, J = 7.4 Hz, 2H), 4.39 – 4.27 (m, 6H), 4.13 (dd, J = 6.8,3.9 Hz, 1H), 4.00 (s, 1H), 3.80 – 3.66 (m, 6H), 3.52 (m, 2H), 3.17 (s, 1H),2.40 (s, 3H), 0.76 (s, 9H), 0.00 (s, 3H), -0.11 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 165.4, 165.0, 164.5, 155.1, 143.5, 143.4, 141.3, 138.2, 138.1,137.3, 137.1, 133.6, 133.3, 133.1, 132.7, 130.1, 130.0, 129.9, 129.73,129.69, 129.64, 129.60, 129.4, 129.2, 129.0, 128.8, 128.37, 128.35, 128.2,128.1, 127.9, 127.6, 127.2, 126.8, 126.2, 125.2, 120.0, 102.3, 101.8, 98.3,97.1, 87.9, 81.9, 78.9, 78.6, 75.13, 75.09, 74.6, 73.9, 73.3, 72.8, 72.7,71.6, 70.7, 69.9, 68.7, 68.5, 68.4, 66.5, 46.8, 25.5, 21.1, 17.9, 0.0, -4.3,-5.0; ESI-HRMS calcd for C 88 H 88 O 20 SSi[M+Na] + 1547.5251, found 1547.5264. 1: Compound 7 (1.524 g, 1 mmol) was dissolved in a mixed solvent of acetone / water (14.4 mL, 9:1 / v:v), cooled to -30 °C, and TCCA (232 mg, 1 mmol) was added. The reaction was maintained at -30 °C. After 5 min, TLC showed that the reaction was almost complete. The reaction was quenched by adding saturated sodium bicarbonate solution, acetone was removed by rotary evaporation, and the mixture was extracted three times with 25 mL of DCM. The organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain a white foamy solid. No further purification was required, and the mixture was directly added to the next step. The obtained hemiacetal and trifluoroacetylimine chloride (324 μL, 2 mmol) were dissolved in dichloromethane (5 mL), and Cs₂CO₃ (487 mg, 1.5 mmol) was added. After reacting overnight, the mixture was filtered, concentrated, and subjected to rapid column chromatography to obtain 1, which was then quickly added to the next step.

[0032] (2) Synthesis of tetrasaccharide acceptor 2 containing o-alkynylbenzoate group

[0033] 9: Under an Ar atmosphere, trifluoroacetylimine ester donor 8 (2.10 g, 1.768 mmol), disaccharide acceptor 5 (1.50 g, 1.608 mmol), and 4 Å molecular sieve (844 mg) were dissolved in dry dichloromethane (17 mL). After stirring at room temperature for 30 minutes, the mixture was cooled to -30 °C, and then TMSOTf (64 μL in 250 μL dry DCM) was added. The reaction was maintained at -30 °C until TLC showed that the reaction was almost complete. The reaction was quenched with saturated sodium bicarbonate solution, filtered, extracted three times with 20 mL of dichloromethane, and the organic phases were combined, washed with saturated sodium chloride solution, dried, evaporated to dryness, and column chromatography (PE / EA, 4:1) to give a white solid 9 (3.7371 g, 83%). 1 H NMR (600 MHz, Chloroform-d) δ 7.90 (d, J = 7.5 Hz, 2H), 7.79 (d, J =7.6 Hz, 2H), 7.65 (d, J = 8.2 Hz, 2H), 7.59 (m, 1H), 7.57 – 7.47 (m, 9H), 7.43 (m, 1H), 7.41 – 7.26 (m, 16H), 7.25 – 7.18 (m, 10H), 7.14 – 7.09 (m, 2H), 7.04 (d, J = 7.8 Hz, 2H), 5.47 (d, J = 2.6 Hz, 2H), 5.25 – 5.21 (m, 1H), 5.09 (m, 1H), 5.04 (dd, J = 7.3, 1.6 Hz, 1H), 4.81 – 4.75 (m, 5H), 4.70 –4.63 (m, 2H), 4.61 (dd, J = 11.9, 1.2 Hz, 1H), 4.46 (d, J = 11.5 Hz, 1H), 4.40 (d, J = 10.5 Hz, 1H), 4.26 (m, 2H), 4.22 – 4.09 (m, 4H), 4.07 – 3.99 (m,2H), 3.90 (dd, J = 6.8, 3.7 Hz, 1H), 3.87 – 3.82 (m, 1H), 3.77 (td, J= 8.8,1.6 Hz, 1H), 3.64 (td, J = 10.3, 3.1 Hz, 2H), 3.56 – 3.39 (m, 6H), 3.34 –3.29 (m, 1H), 3.00 (t, J = 9.4 Hz, 1H), 2.70 – 2.50 (m, 4H), 2.31 (s, 3H),2.14 (s, 3H), 0.70 (s, 9H), -0.07 (s, 3H), -0.30 (s, 3H); 13 C NMR (151 MHz,CDCl3) δ 206.5, 172.6, 165.0, 164.8, 164.7, 153.8, 138.1, 138.04, 137.5,137.4, 137.3, 133.3, 133.22, 133.15, 132.7, 132.5, 130.0, 129.8, 129.74,129.68, 129.66, 129.5, 129.3, 129.2, 129.1, 128.7, 128.5, 128.4, 128.29,128.28, 128.2, 128.13, 128.05, 127.9, 127.7, 127.5, 126.8, 126.2, 102.1,101.3, 99.5, 97.8, 96.6, 94.4, 88.0, 80.1, 78.8, 78.5, 78.0, 75.2, 75.10,75.0, 74.5, 74.3, 73.9, 73.5, 73.0, 72.8, 72.4, 71.5, 70.6, 68.7, 68.6, 67.6,66.1, 64.3, 37.9, 29.9, 28.0, 25.6, 21.1, 17.7, 0.0, -4.12, -4.41;ESI-HRMScalcd for C 101 H 105 Cl3O 26 SSi[M+Na] + 1956.4072, found 1956.4050. 10:Tetrasaccharide 9 (2.48 g, 1.283 mmol) was dissolved in a mixed solvent of acetone / water (14.4 ml, 9:1 / v:v). After cooling to -30 °C, TCCA (298 mg, 1.283 mmol) was added, and the reaction was maintained at -30 °C. After 5 min, TLC showed that the reaction was almost complete. The reaction was quenched by adding saturated sodium bicarbonate solution, and the acetone was removed by rotary evaporation. The mixture was extracted three times with 25 mL of DCM. The organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain a white foamy solid. No further purification was required, and the mixture was directly added to the next step.

[0034] The white foamy solid obtained in the previous step was dissolved in dry acetonitrile (13 mL). o-Alkyne benzoic acid (392 mg, 1.9245 mmol), DABCO (432 mg, 3.849 mmol), EDCI (738 mg, 3.849 mmol), and HOBt (520 mg, 3.849 mmol) were added under ice bath conditions, and the reaction was allowed to return to room temperature naturally. The reaction was allowed to proceed until TLC monitoring showed that it was essentially complete. The mixture was then quenched with water, extracted three times with 20 mL of DCM, and the organic phases were combined. The mixture was washed with saturated sodium bicarbonate solution and saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness. Column chromatography (PE / EA, 6:1) yielded a white solid 10 (1.9020 g, 74% over 2 steps). 1 H NMR (600 MHz, Chloroform-d) δ 7.89 (m, 3H), 7.86 – 7.83 (m, 2H), 7.71 –7.68 (m, 2H), 7.67 – 7.60 (m, 5H), 7.57 – 7.47 (m, 8H), 7.46 – 7.34 (m, 18H), 7.32 – 7.26 (m, 6H), 7.26 – 7.23 (m, 2H), 5.99 (d, J = 7.8 Hz, 1H), 5.61 (s,1H), 5.48 (s, 1H), 5.28 (t, J = 7.5 Hz, 1H), 5.16 (dd, J = 9.0, 7.8 Hz, 1H), 5.07 (d, J = 7.2 Hz, 1H), 5.01 (t, J = 8.1 Hz, 1H), 4.91 (t, J = 4.9 Hz, 1H), 4.89 – 4.81 (m, 4H), 4.67 (d, J= 11.9 Hz, 1H), 4.55 (m, 2H), 4.41 – 4.37 (m,2H), 4.33 (dd, J = 11.5, 2.3 Hz, 1H), 4.30 – 4.24 (m, 2H), 4.22 (dd, J =11.7, 5.7 Hz, 1H), 4.14 (dd, J = 11.4, 5.8 Hz, 1H), 4.08 – 4.02 (m, 2H), 3.92(t, J = 9.1 Hz, 1H), 3.83 (q, J = 10.2, 9.5 Hz, 2H), 3.76 – 3.64 (m, 4H),3.58 – 3.50 (m, 3H), 3.41 (m, 1H), 3.35 (t, J = 8.9 Hz, 1H), 2.82 – 2.70 (m,2H), 2.69 – 2.58 (m, 2H), 2.50 (t, J = 7.2 Hz, 2H), 2.25 (s, 3H), 1.68 – 1.64(m, 4H), 1.56 – 1.50 (m, 2H), 1.00 (t, J = 7.3 Hz, 3H), 0.77 (s, 9H), -0.00(s, 3H), -0.23 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 206.4, 172.6, 164.8, 164.7,164.6, 163.2, 153.7, 138.1, 137.44, 137.37, 137.2, 134.5, 133.3, 133.2,133.0, 132.7, 132.3, 130.7, 129.9, 129.8, 129.7, 129.63, 129.56, 129.4,129.3, 129.12, 129.08, 129.05, 128.6, 128.5, 128.4, 128.30, 128.25, 128.2,128.0, 127.9, 127.7, 127.6, 127.2, 126.6, 126.2, 125.8, 102.0, 101.2, 99.3,98.1, 97.4, 97.3, 94.4, 92.5, 79.8, 78.9, 78.7, 78.4, 77.7, 75.2, 75.1, 74.3,74.2, 74.1, 73.4, 73.3, 72.9, 72.5, 71.8, 68.7, 68.5, 67.6, 67.0, 66.1, 64.0,37.9, 30.7, 29.9, 27.9, 25.6, 22.1, 19.5, 17.7, 13.7, 0.0, -4.13, -4.42;ESI-HRMS calcd for C 107 H 111 Cl3O 30 Si[M+Na] + 2031.5887, found 2031.5859. 2: Tetrasaccharide o-alkynylbenzoate donor 10 (1.902 g, 0.946 mmol) was dissolved in a MeOH / DCM (20 mL, 1:1 / v:v) mixed solvent. AcOH (1.6 mL) was added, followed by hydrazine hydrate (0.4 mL, 85% wt). The reaction was maintained at room temperature until the reaction was almost complete as monitored by TLC. 2 mL of acetone was added and stirred for 5 min. The reaction was then quenched with saturated sodium bicarbonate solution. The mixture was extracted three times with 25 mL of DCM. The organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain a white foamy solid. No further purification was required before proceeding to the next step.

[0035] Under an Ar atmosphere, the white foamy solid obtained in the previous step was dissolved in dry DCM (5 mL). DMAP (462 mg, 3.784 mmol) and AllocCl (201 μL, 1.892 mmol) were added in an ice bath, and the reaction was allowed to return to room temperature naturally. The reaction was allowed to proceed until TLC monitoring showed near-complete completion. Saturated sodium bicarbonate solution was added to quench the reaction, and the mixture was extracted three times with 15 mL of DCM. The organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain a white foamy solid. No further purification was required before proceeding to the next step. The white foamy solid obtained in the previous step was dissolved in dry pyridine (6 mL), and pyridine hydrogen fluoride (3 mL, 70%) was added under ice bath conditions. The reaction was allowed to return to room temperature naturally. The reaction was continued until TLC showed that the reaction was essentially complete. The solution was diluted with EA, neutralized with saturated sodium bicarbonate solution, and extracted three times with 30 mL of EA. The organic phases were combined, washed with 1M HCl, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness. Column chromatography (PE / EA, 4:1 – 3:1) yielded white solid 2 (1.3824 g, 78% over 3 steps). ¹H NMR (600 MHz, Chloroform-d) δ 7.83 (dd, J = 7.9, 1.3 Hz, 1H), 7.81 – 7.74 (m,4H), 7.67 – 7.60 (m, 4H), 7.56 – 7.53 (m, 2H), 7.53 – 7.45 (m, 7H), 7.41 (d, J = 1.4 Hz, 1H), 7.38 – 7.27 (m, 22H), 7.24 (t, J = 7.4 Hz, 2H), 7.16 – 7.13(m, 2H), 5.96 (ddt, J = 16.6, 10.4, 5.8 Hz, 1H), 5.88 (d, J = 7.8 Hz, 1H), 5.51 (d, J = 6.1 Hz, 2H), 5.42 – 5.36 (m, 1H), 5.30 – 5.24 (m, 2H), 5.04 (d, J = 7.6 Hz, 1H), 4.95 – 4.87 (m, 3H), 4.84 – 4.77 (m, 4H), 4.68 – 4.64 (m,3H), 4.57 (d, J = 11.1 Hz, 1H), 4.49 (d, J= 10.7 Hz, 1H), 4.34 – 4.27 (m,3H), 4.23 (m, 4H), 4.07 (t, J = 8.6 Hz, 1H), 3.98 (dd, J = 7.2, 4.6 Hz, 1H),3.82 (t, J = 9.2 Hz, 1H), 3.75 (dt, J = 8.9, 4.4 Hz, 1H), 3.68 – 3.56 (m,6H), 3.52 – 3.47 (m, 2H), 3.36 (m, 1H), 3.25 (t, J = 9.1 Hz, 1H), 2.52 (dd, J = 4.8, 2.5 Hz, 1H), 2.43 (t, J = 7.1 Hz, 2H), 1.65 – 1.53 (m, 5H), 1.51 –1.43 (m, 2H), 0.93 (t, J = 7.3 Hz, 3H); 13C NMR (151 MHz, CDCl3) δ 166.1,164.79, 164.77, 164.5, 163.2, 154.9, 153.8, 138.0, 137.6, 137.2, 134.6,133.3, 133.2, 133.1, 132.3, 131.6, 130.7, 129.81, 129.75, 129.73, 129.66,129.5, 129.4, 129.14, 129.08, 129.05, 128.6, 128.4, 128.33, 128.30, 128.24, 128.19, 128.15, 128.12, 128.09, 127.7, 127.2, 126.7, 126.2, 125.9, 119.1, 102.2, 101.3, 99.3, 98.3, 97.30, 97.25, 94.4, 92.4, 79.9, 79.0, 78.9, 78.5, 78.0, 77.8, 76.2, 75.1, 75.0, 74.9, 74.2, 74.0, 73.3, 73.1, 72.9, 72.3, 71.7, 68.7, 68.5, 67.6, 67.0, 66.3, 30.7, 22.1, 19.5, 13.7; ESI-HRMS calcd forC 100 H 95 Cl3O 30 [M+Na] + 1903.4866, found 1903.4894. (3) Synthesis of reducing-terminal trisaccharide receptor 3

[0036] 3: Under an Ar atmosphere, trifluoroacetylimine ester disaccharide donor 11 (2.91 g, 2.613 mmol), monosaccharide acceptor 12 (1.62 g, 2.376 mmol), and 4 Å molecular sieve (1.25 g) were dissolved in dry dichloromethane (25 mL). After stirring at room temperature for 30 minutes, the mixture was cooled to -30 °C, and then TMSOTf (95 μL, 0.523 mmol, in 500 μL dry DCM) was added. The reaction was maintained at -30 °C until TLC showed that the reaction was almost complete. The reaction was quenched with saturated sodium bicarbonate solution, filtered, extracted three times with 20 mL of dichloromethane, and the organic phases were combined, washed with saturated sodium chloride solution, dried, and evaporated to dryness to obtain a pale yellow foamy solid. No further purification was required before proceeding to the next step. The white foamy solid obtained in the previous step was dissolved in dry pyridine (7 mL), and pyridine hydrogen fluoride (3.5 mL, 70%) was added under ice bath conditions. The reaction was allowed to return to room temperature naturally. The reaction was continued until TLC showed that the reaction was almost complete. The solution was diluted with EA, neutralized with saturated sodium bicarbonate solution, and extracted three times with 35 mL of EA. The organic phases were combined, washed with 1M HCl, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and evaporated to dryness. Column chromatography with PE / EA (3:1) yielded white solid 3 (2.0130 g, 85% over 2 steps). 1 H NMR (600MHz, Chloroform-d) δ 7.93 (d, J = 7.6 Hz, 2H), 7.80 (d, J = 7.6 Hz, 2H), 7.62(d, J = 7.7 Hz, 2H), 7.55 (d, J = 7.3 Hz, 1H), 7.53 – 7.49 (m, 2H), 7.43 (dt, J = 18.9, 7.5 Hz, 4H), 7.35 – 7.27 (m, 18H), 7.24 – 7.17 (m, 4H), 7.11 (s,1H), 5.43 (s, 1H), 5.16 – 5.11 (m, 3H), 5.01 (t, J = 8.4 Hz, 1H), 4.95 (t, J = 8.3 Hz, 2H), 4.91 (d, J = 5.0 Hz, 1H), 4.80 (dd, J = 11.3, 5.3 Hz, 2H), 4.62 (d, J = 11.2 Hz, 1H), 4.45 – 4.33 (m, 3H), 4.28 (dd, J = 10.5, 4.9 Hz, 1H), 4.22 (d, J = 3.3 Hz, 2H), 4.15 – 4.08 (m, 2H), 4.05 – 3.99 (m, 2H), 3.82(q, J = 8.1 Hz, 1H), 3.70 (d, J = 21.2 Hz, 1H), 3.62 (t, J = 10.2 Hz, 1H), 3.58 – 3.50 (m, 3H), 3.46 (dd,J = 8.4, 4.8 Hz, 1H), 3.40 (s, 1H), 3.26 (dd, J = 20.7, 11.3 Hz, 2H), 2.96 (d, J = 57.4 Hz, 2H), 2.57 – 2.51 (m, 3H), 2.40(td, J = 6.5, 3.7 Hz, 2H), 2.08 (s, 3H), 1.39 – 1.24 (m, 4H), 1.03 (s, 2H); 13 CNMR (151 MHz, CDCl3) δ 206.6, 172.5, 166.5, 164.6, 138.0, 137.5, 137.3,133.6, 133.2, 130.1, 129.78, 129.75, 129.7, 129.6, 129.5, 129.3, 128.9,128.8, 128.7, 128.64, 128.58, 128.5, 128.44, 128.40, 128.36, 128.1, 128.0,127.3, 126.5, 126.3, 101.9, 101.5, 100.8, 79.0, 78.1, 78.0, 76.6, 76.4, 75.3,75.0, 74.9, 74.4, 73.0, 72.8, 68.9, 68.8, 67.2, 66.6, 65.7, 63.0, 37.9, 30.0,29.2, 28.0, 23.1; ESI-HRMS calcd for C 85 H 87 NO 23 [M+Na] + 1512.5561, found 1512.5558. (4) Synthesis of decasaccharide skeleton compound PBG-1

[0037] PBG-1: Under an Ar atmosphere, trisaccharide trifluoroacetylimine ester donor 1 (1.210 g, 0.761 mmol), tetrasaccharide receptor 2 (750 mg, 0.634 mmol), and 4Å molecular sieve (280 mg) were dissolved in a dry dichloromethane / trifluorotoluene mixed solvent (14 mL, 1:1 / v:v). After stirring at room temperature for 30 minutes, the mixture was cooled to -30 °C, and then TBSOTf (52 μL, 0.228 mmol, in 250 μL dry DCM) was added. The reaction was maintained at -30 °C until TLC showed that the reaction was almost complete. The temperature was then raised to 0 °C, and trisaccharide receptor 3 (907 mg, 0.609 mmol) and 5Å molecular sieve (300 mg) were added, followed by PPh3AuNTf2 (169 mg, 0.228 mmol). The mixture was then slowly raised to room temperature. The reaction was continued until TLC showed that it was nearly complete. The mixture was then quenched with saturated sodium bicarbonate solution, filtered, extracted three times with 20 mL of dichloromethane, and the organic phases were combined. The mixture was washed with saturated sodium chloride solution, dried, and evaporated to dryness. Column chromatography was performed using toluene / dichloromethane / acetone (22:1:1). This yielded a white, foamy solid, PBG-1 (1.3103 g, 90%). 1 H NMR (400 MHz, Chloroform- d ) δ 7.82 (d, J = 7.4 Hz, 2H), 7.75 (s, 5H), 7.70 – 7.28(m, 93H), 7.20 (t, J = 8.8 Hz, 12H), 5.92 (ddt, J = 16.4, 10.9, 5.8 Hz, 1H),5.48 (d, J = 2.0 Hz, 2H), 5.40 – 5.25 (m, 5H), 5.13 (p, J = 5.4 Hz, 4H), 5.01– 4.55 (m, 31H), 4.43 – 3.81 (m, 40H), 3.75 – 3.14 (m, 34H), 2.90 (ddd, J =15.8, 11.6, 5.2 Hz, 2H), 2.57 (q, J = 6.2 Hz, 2H), 2.42 (q, J= 6.6, 6.0 Hz,2H), 2.10 (s, 3H), 1.32 (s, 4H), 1.12 – 1.03 (m, 2H), 0.60 (s, 9H), -0.18 (s,3H), -0.33 (s, 3H); 13 C NMR (101 MHz, CDCl3) δ 206.6, 172.6, 167.9, 165.4,164.8, 164.7, 164.5, 164.1, 155.1, 154.9, 153.9, 143.50, 143.46, 141.3,138.0, 137.9, 137.3, 137.2, 137.0, 133.3, 133.0, 132.4, 131.6, 131.1, 130.0,129.9, 129.7, 129.6, 129.5, 129.2, 129.09, 129.06, 128.9, 128.7, 128.6, 128.50, 128.45, 128.41, 128.38, 128.34, 128.29, 128.25, 128.23, 128.15, 128.0, 127.9, 127.8, 127.3, 127.2, 126.5, 126.43, 126.38, 126.3, 125.9, 125.4, 120.1, 119.2, 101.8, 101.6, 99.5, 96.4, 94.5, 81.8, 79.3, 79.0, 75.7, 74.8, 74.5, 68.7, 65.7, 30.7, 30.0, 29.8, 19.3, 17.9, 13.9, -4.3, -5.1; ESI-HRMS calcd for C 253 H 246 Cl3NO 71 Si [M+Na] + 4591.4553, found 4593.4507. (5) Synthesis of compound BG-30

[0038] 13: Under an Ar atmosphere, the trisaccharide trifluoroacetylimine ester donor 28 (44 mg, 0.031 mmol) was dissolved in a dry dichloromethane / trifluorotoluene mixed solvent (510 μL, 1:1 / v:v) with a decasaccharide acceptor (90 mg, 0.020 mmol) and a 4 Å molecular sieve (26 mg). After stirring at room temperature for 30 minutes, the mixture was cooled to -30 °C, and then TMSOTf (12 μL, 0.062 mmol, in 25 μL dry DCM) was added. The reaction was maintained at -30 °C until TLC showed that the reaction was essentially complete. The reaction was quenched with saturated sodium bicarbonate solution, filtered, extracted three times with 5 mL of dichloromethane, and the organic phases were combined, washed with saturated sodium chloride solution, dried, evaporated to dryness, and subjected to column chromatography with toluene / dichloromethane / acetone (22:1:1). A white foamy solid 13 (104 mg, 94%) was obtained. 1 H NMR (600MHz, Chloroform- d ) δ 7.90 – 7.85 (m, 2H), 7.79 – 7.72 (m, 7H), 7.71 – 7.67(m, 4H), 7.64 – 7.60 (m, 5H), 7.59 – 7.47 (m, 22H), 7.43 – 7.28 (m, 71H),7.24 – 7.15 (m, 34H), 7.13 – 7.07 (m, 13H), 6.00 – 5.90 (m, 1H), 5.48 (s,1H), 5.46 (d, J = 5.7 Hz, 1H), 5.42 (s, 1H), 5.40 (q, J = 1.5 Hz, 1H), 5.38 –5.33 (m, 3H), 5.31 – 5.26 (m, 2H), 5.19 – 5.12 (m, 5H), 5.10 (s, 1H), 5.07(s, 1H), 4.97 (t, J = 6.4 Hz, 1H), 4.92 (d, J = 6.2 Hz, 1H), 4.88 – 4.61 (m,30H), 4.57 – 4.51 (m, 4H), 4.44 – 4.37 (m, 10H), 4.28 (dd, J = 10.8, 5.1 Hz,2H), 4.23 – 3.82 (m, 35H), 3.79 (t, J= 6.6 Hz, 1H), 3.74 – 3.11 (m, 59H),3.06 (t, J = 8.5 Hz, 2H), 3.00 – 2.88 (m, 2H), 2.55 (dt, J = 8.0, 6.5 Hz,2H), 2.41 (q, J = 6.9 Hz, 2H), 2.09 (s, 3H), 1.31 (m, 4H), 0.99 (d, J = 32.4Hz, 2H), 0.62 (s, 9H), -0.16 (s, 3H), -0.31 (s, 3H); 13C NMR (151 MHz, CDCl3) δ206.5, 172.5, 165.5, 164.9, 164.8, 164.7, 164.54, 164.45, 164.3, 164.2,155.1, 154.9, 143.6, 143.5, 141.4, 138.8, 138.6, 138.5, 138.3, 138.1, 137.5,137.3, 137.1, 133.1, 133.0, 132.8, 131.7, 130.1, 130.0, 129.9, 129.83,129.78, 129.71, 129.67, 129.49, 129.45, 129.3, 129.0, 128.63, 128.57, 128.5,128.44, 128.43, 128.40, 128.38, 128.37, 128.34, 128.30, 128.26, 128.22,128.20, 128.17, 128.12, 128.10, 128.00, 127.98, 127.96, 127.93, 127.87,127.78, 127.76, 127.6, 127.5, 127.41, 127.36, 127.2, 126.7, 126.5, 126.44,126.39, 126.3, 125.4, 120.1, 119.2, 101.9, 101.8, 101.7, 101.6, 101.1, 99.7,98.6, 97.9, 96.7, 84.6, 81.9, 79.0, 78.9, 77.8, 77.7, 75.4, 75.2, 75.0, 74.8,74.6, 74.5, 74.4, 74.3, 74.0, 73.6, 73.3, 73.2, 72.8, 72.2, 72.1, 70.1, 69.1,68.8, 68.7, 67.2, 66.6, 66.5, 66.3, 66.2, 63.9, 46.8, 37.9, 30.0, 29.8, 29.1,28.0, 27.3, 25.6, 23.1, 18.0, 1.2, 0.1, -4.2, -5.0; MALDI-TOF-HRMS calcd forC 324 H 317 NO 86 Si [M+Na] +5648.0124, found 5648.5807.

[0039] 14: Under an Ar atmosphere, monosaccharide donor 27 (24 mg, 0.042 mmol), decadecylase acceptor (75 mg, 0.014 mmol), and 4Å molecular sieve (28 mg) were dissolved in a 12 mL digestion tube in a DCM / PhCF3 (560 μL, 1:1 / v:v) mixed solvent. After stirring at room temperature for 30 min, the mixture was cooled to -20 °C, and NIS (19 mg, 0.084 mmol) and TMSOTf (1.5 μL, 0.008 mmol, in 25 μL dry DCM) were added. The reaction was maintained at -20 °C until TLC showed that the reaction was basically complete. The reaction was quenched with saturated sodium bicarbonate solution, diluted with 5 mL of DCM, filtered, extracted three times with 5 mL of DCM, and the organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, evaporated to dryness, and column chromatography with Tol / DCM / Acetone (22:1:1) to obtain a white powder 14 (68 mg, 84%). 1 H NMR (600 MHz, Chloroform- d ) δ 7.93 (d, J = 7.9 Hz, 2H), 7.88 (d, J =7.9 Hz, 2H), 7.78 – 7.74 (m, 6H), 7.68 (d, J = 8.4 Hz, 2H), 7.65 – 7.61 (m,7H), 7.60 – 7.27 (m, 135H), 7.25 – 7.07 (m, 80H), 5.54 (s, 1H), 5.50 – 5.46(m, 2H), 5.43 (s, 1H), 5.37 (t, J = 6.4 Hz, 2H), 5.30 – 5.24 (m, 4H), 5.20 –5.11 (m, 7H), 5.07 (s, 1H), 5.00 – 4.51 (m, 46H), 4.46 – 3.93 (m, 58H), 3.84– 3.14 (m, 83H), 3.03 – 2.89 (m, 4H), 2.55 (dt, J = 12.4, 6.5 Hz, 2H), 2.40(td, J= 14.7, 13.9, 7.2 Hz, 2H), 2.08 (d, J = 7.6 Hz, 3H), 1.37 – 1.31 (m,4H), 1.05 – 0.97 (m, 2H), 0.62 (s, 9H), -0.16 (d, J = 8.0 Hz, 3H), -0.29 (d, J = 4.6 Hz, 3H); 13C NMR (151 MHz, CDCl3) δ 206.5, 172.5, 165.5, 165.2, 164.8,164.7, 164.6, 164.5, 164.2, 155.1, 143.6, 143.5, 141.4, 138.8, 138.6, 138.5,138.3, 138.1, 137.5, 137.3, 137.1, 133.3, 133.1, 132.8, 130.0, 129.9, 129.82,129.77, 129.7, 129.5, 129.3, 129.2, 128.6, 128.5, 128.43, 128.39, 128.35,128.33, 128.29, 128.25, 128.19, 128.16, 128.13, 128.10, 128.09, 128.03,127.97, 127.95, 127.92, 127.86, 127.79, 127.76, 127.63, 127.58, 127.5,127.40, 127.35, 127.3, 127.2, 126.73, 126.66, 126.5, 126.42, 126.39, 126.32,126.25, 126.2, 125.4, 120.1, 101.9, 101.6, 101.3, 101.1, 99.7, 99.3, 98.9,98.5, 84.6, 81.9, 81.7, 79.4, 79.1, 79.0, 77.8, 77.6, 75.4, 75.2, 75.0, 74.8,74.6, 74.5, 74.4, 74.1, 74.0, 73.6, 73.4, 73.1, 72.8, 72.2, 70.1, 69.1, 68.8,68.5, 67.6, 67.2, 66.6, 66.5, 66.3, 66.2, 46.8, 37.9, 30.0, 29.8, 29.5, 29.1,27.9, 18.0, -4.3, -5.0. MALDI-TOF-HRMS calcd for C 324 H 317 NO 86 Si [M+Na] + 5648.0124, found 5648.5807.

[0040] 15: Under an Ar atmosphere, trisaccharide donor 29 (17 mg, 0.011 mmol), tetradecyl acceptor (40 mg, 0.007 mmol), and 4Å molecular sieve (9 mg) were dissolved in a DCM / PhCF3 (180 μL, 1:1 / v:v) mixed solvent in a 12 mL digestion tube. After stirring at room temperature for 30 min, the mixture was cooled to -20 °C, and TMSOTf (0.4 μL, 0.002 mmol, in 25 μL dry DCM) was added. The reaction was maintained at -20 °C until TLC showed that the reaction was basically complete. The reaction was quenched with saturated sodium bicarbonate solution, diluted with 5 mL of DCM, filtered, extracted three times with 5 mL of DCM, and the organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, evaporated to dryness, and subjected to column chromatography with Tol / DCM / Acetone (22:1:1) to obtain a white powder 15 (38 mg, 77%). 1 H NMR (600 MHz, Chloroform- d ) δ 7.90 (s, 5H), 7.82 (s, 2H), 7.73 (d, J = 8.5 Hz, 7H), 7.68 –7.27 (m, 121H), 7.24 – 6.97 (m, 108H), 5.53 (s, 1H), 5.46 (s, 1H), 5.42 (s,1H), 5.36 (s, 3H), 5.33 – 5.30 (m, 1H), 5.24 (t, J = 15.0 Hz, 4H), 5.19 –5.02 (m, 10H), 4.98 – 3.89 (m, 115H), 3.87 – 3.14 (m, 94H), 3.13 – 2.85 (m,10H), 2.61 – 2.47 (m, 2H), 2.44 – 2.33 (m, 2H), 2.08 (s, 3H), 1.33 (s, 4H), 1.01 (d, J = 18.5 Hz, 2H), 0.58 (s, 9H), -0.21 (s, 3H), -0.38 (s, 3H); 13C NMR(151 MHz, CDCl3) δ 206.5, 172.5, 165.3, 165.1, 164.6, 164.3, 138.74, 138.72,138.6, 138.4, 138.31, 138.25, 138.1, 138.02, 137.96, 137.5, 137.2, 133.1,133.0, 130.1, 129.9, 129.81, 129.76, 129.7, 129.53, 129.45, 129.4, 129.2,128.62, 128.56, 128.5, 128.42, 128.39, 128.33, 128.29, 128.23, 128.20,128.16, 128.12, 128.09, 128.07, 128.05, 128.03, 127.98, 127.96, 127.92,127.90, 127.87, 127.83, 127.80, 127.74, 127.70, 127.63, 127.58, 127.5, 127.4,127.2, 126.7, 126.5, 126.4, 126.31, 126.25, 126.2, 104.2, 101.9, 101.8,101.6, 101.3, 84.8, 84.6, 82.9, 82.1, 81.9, 81.7, 79.0, 78.2, 77.9, 77.8,75.7, 75.4, 75.1, 75.02, 75.00, 74.95, 74.8, 74.7, 74.6, 74.4, 74.1, 74.0,73.8, 73.6, 73.4, 73.2, 73.1, 72.0, 69.0, 68.8, 67.2, 54.1, 50.3, 37.9, 30.0,29.8, 29.1, 27.9, 23.1, 22.8, 18.8, 17.9, 17.6, 12.2, -4.2, -5.06, -5.08.MALDI-TOF-HRMS calcd for C 420 H 413 NO 105 Si [M+Na] + 7200.6670, found 7200.0502.

[0041] BG-30: In a 12 mL digestion tube, dissolve the fully protected polysaccharide PBG-30 (38 mg, 0.005 mmol) in 750 μL of dry THF, add 750 μL of freshly prepared NaOMe / MeOH solution (1 M), and heat to 60 °C until MALDI-TOF shows complete removal of all acyl groups. Add Dowex ® 50-8 H + Neutralize the resin to neutral, filter out the resin, and evaporate to dryness. Then remove small molecule components by passing through dextran gel LH-20 (DCM:MeOH=2:1), and evaporate to dryness before use for hydrogenation reaction.

[0042] The deacylated polysaccharide was dissolved in 3 mL of a DCM / t-BuOH / H2O (3:6:1) mixed solvent. 50 mg of Pd / C was carefully added, and the mixture was purged with hydrogen gas (1 atm) in an ice bath. The reaction was allowed to return to room temperature naturally for 48–96 h until MALDI-TOF showed complete removal of all protecting groups. The mixture was diluted with 5 mL of water, the organic solvent was removed by rotary evaporation, Pd / C was removed by filtration, the mixture was evaporated to dryness, and then separated by G-10 (H2O) followed by lyophilization to obtain the target polysaccharide compound BG30 (2 mg, 14% over 2 steps). 1 H NMR (600 MHz, Deuterium Oxide) δ 4.64 (d, J = 8.2 Hz, 11H), 4.44 – 4.38 (m, 5H), 4.36 (d, J = 8.7 Hz, 1H), 4.09 (d, J = 8.4 Hz, 5H), 3.82 – 3.74 (m, 18H), 3.68 – 3.55(m, 31H), 3.50 – 3.17 (m, 75H), 2.88 (t, J = 7.0 Hz, 2H), 1.61 – 1.49 (m,4H), 1.36 – 1.28 (m, 2H); 13 C NMR (151 MHz, D2O) δ 102.7, 102.5, 102.4, 102.0,84.2, 84.0, 75.9, 75.7, 75.6, 74.8, 74.5, 73.3, 73.1, 73.0, 69.6, 69.4, 68.8,68.1, 60.7, 39.4, 28.3, 26.4, 22.2; ESI-HRMS calcd for C 107 H 183 NO86 [M+H] + 2859.0050, found 2859.0068. General Method A: Dissolve the starting material in a 5:1 EA / DEA mixed solvent, stir at room temperature until the reaction is complete as shown by TLC, dilute with EA, evaporate to dryness, and perform column chromatography.

[0043] General Method B: Dissolve the raw material in a THF / AcOH (2:1) mixed solvent, add zinc and copper reagents, stir the reaction at room temperature until TLC shows that the reaction is basically complete, filter, quench with saturated sodium bicarbonate solution, extract three times with DCM, combine the organic phases, wash with saturated sodium chloride solution, dry with anhydrous sodium sulfate, evaporate to dryness, and column chromatography.

[0044] General Method C: Under Ar atmosphere and in an ice bath, dissolve the raw material, Pd(PPh3)4, in dry DCM, add PhSiH3, maintain the reaction at 0 ℃, and after 5-10 min, TLC shows that the reaction is basically complete, and directly load the sample onto the column for chromatography.

[0045] General Method D: Dissolve the raw material in a DCM / MeOH (1:1) mixed solvent, add AcOH and then N2H4·H2O, maintain the reaction at room temperature until TLC shows that the reaction is basically complete, add Acetone and stir for 5 min, then quench with saturated sodium bicarbonate solution, extract with DCM three times, combine the organic phases, wash with saturated sodium chloride solution, dry with anhydrous sodium sulfate, evaporate to dryness, and column chromatography.

[0046] General Method E: Under Ar atmosphere, the donor (3 eq per -OH), acceptor, and 4Å molecular sieve were dissolved in a DCM / PhCF3 (1:1, 0.1 M) mixed solvent in a 12 mL digestion tube. After stirring at room temperature for 30 min, the mixture was cooled to -20 °C, and NIS (2 eq per donor) and TMSOTf (in 25 μL dry DCM, 0.15 eq per donor) were added. The reaction was maintained at -20 °C until TLC showed that the reaction was basically complete. The reaction was quenched with saturated sodium bicarbonate solution, diluted with 5 mL of DCM, filtered, extracted three times with 5 mL of DCM, and the organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, evaporated to dryness, and column chromatography with Tol / DCM / Acetone (22:1:1).

[0047] General Method F: Under Ar atmosphere, the donor (1.5 eq per -OH), acceptor, and 4Å molecular sieve were dissolved in a DCM / PhCF3 (1:1, 0.1M) mixed solvent in a 12 mL digestion tube. After stirring at room temperature for 30 min, the mixture was cooled to -20 °C, and TMSOTf (in 25 μL dry DCM, 0.15 eq per donor) was added. The reaction was maintained at -20 °C until TLC showed that the reaction was basically complete. The reaction was quenched with saturated sodium bicarbonate solution, diluted with 5 mL of DCM, filtered, extracted three times with 5 mL of DCM, and the organic phases were combined, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, evaporated to dryness, and column chromatography with Tol / DCM / Acetone (22:1:1).

[0048] General Method G: In a 12 mL digestion tube, dissolve the fully protected polysaccharide in 750 μL of dry THF, add 750 μL of freshly prepared NaOMe / MeOH solution (1 M), and heat to 60 °C until MALDI-TOF shows complete removal of all acyl groups. Neutralize to neutral with Dowex® 50-8 H+ resin, filter off the resin, and evaporate to dryness. Then remove small molecule components by passing through dextran gel LH-20 (DCM:MeOH=2:1), and evaporate to dryness before use for hydrogenation.

[0049] The deacylated polysaccharide was dissolved in 3 mL of a DCM / t-BuOH / H2O (3:6:1) mixed solvent. 50 mg of Pd / C was carefully added, and the mixture was purged with hydrogen gas (1 atm) in an ice bath. The reaction was allowed to return to room temperature naturally for 48–96 h until MALDI-TOF showed complete removal of all protecting groups. The mixture was diluted with 5 mL of water, the organic solvent was removed by rotary evaporation, Pd / C was removed by filtration, the mixture was evaporated to dryness, and then separated by G-10 (H2O) followed by lyophilization to obtain the target polysaccharide compound.

[0050] In a general H:Ar atmosphere, the sulfation precursor, SO3·Et3N (5 eq per -OH), was dissolved in dry DMF (1 mL) in a 12 mL digestion tube. After stirring at 60 °C for 48 h, the reaction was monitored by mass spectrometry to be basically complete. Triethylamine was added for quenching, and reagents were removed by LH-20 (DCM:MeOH=1:1). No further purification was required before proceeding to the next step.

[0051] Example 2: Synthesis of compound BG-1 Starting from PBG-1, feed was performed according to general method G to obtain white powder BG-1 (5 mg, 43%).

[0052]

[0053] 1H NMR (600 MHz, Deuterium Oxide) δ 4.75 (d, J = 8.0 Hz, 9H), 4.48(d, J = 8.0 Hz, 1H), 3.95 – 3.89 (m, 15H), 3.81 – 3.70 (m, 29H), 3.59 – 3.46(m, 42H), 3.43 – 3.39 (m, 2H), 3.35 (dd, J = 9.4, 7.9 Hz, 2H), 3.00 (t, J =7.7 Hz, 2H), 1.71 – 1.65 (m, 4H), 1.46 (p, J = 7.9 Hz, 2H). 13 C NMR (151 MHz,D2O) δ 102.8, 102.5, 84.0, 76.0, 75.6, 73.4, 73.3, 70.1, 69.6, 68.1, 60.7,39.3, 28.1, 26.4, 22.1. ESI-HRMS calcd for C65H114NO51+ [M+H] + 1724.6532, found 1724.5866. Example 3: Synthesis of compound BG-2 Starting from PBG-1, feed was performed according to general methods B, E, and G to obtain white powder BG-2 (7 mg, 43%).

[0054]

[0055] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.66 (m, 9H), 4.52 (d, J =7.9 Hz, 1H), 4.46 (d, J = 8.1 Hz, 1H), 4.20 (d, J = 10.5 Hz, 1H), 3.91 – 3.88(m, 12H), 3.72 – 3.65 (m, 22H), 3.60 – 3.4 (m, 32H), 3.38 (t, J = 9.4 Hz,2H), 3.32 (m, 2H), 2.97 (t, J= 7.8 Hz, 2H), 1.70 – 1.62 (m, 4H), 1.40 – 1.45 (m, 2H). 13 C NMR (151 MHz, D2O) δ 102.8, 102.5, 102.4, 101.9, 84.1, 84.0,75.9, 75.6, 75.5, 72.9, 70.1, 69.6, 68.1, 60.7, 39.3, 28.1, 26.4, 22.1. ESI-HRMS calcd for C71H124NO56+ [M+H] + 1886.6880, found 1886.5900. Example 4: Synthesis of compound BG-3 Starting from PBG-1, the mixture was fed according to general method B, F (with compound 28 as the donor), and G to obtain white powder BG-3 (7 mg, 37%).

[0056]

[0057] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.66 (m, 11H), 4.52 (d, J = 7.9 Hz, 1H), 4.45 (d, J = 8.1 Hz, 1H), 4.19 (d, J = 10.5 Hz, 1H), 3.93 –3.85 (m, 12H), 3.78 – 3.64 (m, 22H), 3.59 – 3.41 (m, 32H), 3.37 (t, J = 9.4Hz, 2H), 3.32 (m, 2H), 2.97 (t, J = 7.8 Hz, 2H), 1.69 – 1.61 (m, 4H), 1.42(m, 2H). 13 C NMR (151 MHz, D2O) δ 102.8, 102.6, 102.5, 101.9, 84.2, 84.0, 76.0,75.6, 75.5, 73.4, 73.3, 72.9, 70.1, 69.6, 68.1, 60.7, 39.3, 28.1, 26.4, 22.1.ESI-HRMS calcd for C83H144NO66+ [M+H]+ 2210.7937, found 2210.8003. Example 5: Synthesis of compound BG-4 Starting from PBG-1, the mixture was fed according to general method B, F (with compound 29 as the donor), and G to obtain white powder BG-4 (8 mg, 39%).

[0058]

[0059] 1 H NMR (600 MHz, Chloroform- d ) δ 4.55 (dd, J = 8.2, 2.1 Hz, 1H), 4.53– 4.50 (m, 2H), 4.50 – 4.47 (m, 1H), 4.26 – 4.18 (m, 3H), 3.92 (dt, J = 12.7,2.5 Hz, 11H), 3.89 – 3.84 (m, 4H), 3.82 – 3.68 (m, 23H), 3.65 – 3.43 (m,39H), 3.43 – 3.29 (m, 7H), 3.00 (t, J = 7.5 Hz, 2H), 1.65-1.72 (m, 4H), 1.49– 1.41 (m, 2H). 13 C NMR (151 MHz, CDCl3) δ 105.6, 105.4, 105.3, 105.0, 104.5,87.3, 87.0, 86.8, 86.6, 86.4, 78.5, 78.5, 78.2, 78.1, 77.5, 77.1, 76.0, 75.8,75.7, 75.6, 75.4, 72.6, 72.2, 72.1, 72.0, 72.0, 71.5, 71.2,70.7, 70.6, 63.2,41.9, 30.7, 28.9, 24.6. calcd for C83H144NO66+ [M+H] + 2210.7937, found 2210.8011. Example 6: Synthesis of compound BG-5 Starting from PBG-1, feed was carried out according to general methods B, F (compound 28 as donor), C, E, G, to obtain white powder BG-5 (7 mg, 30%).

[0060]

[0061] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.75 – 4.71 (m, 9H), 4.50 (dd, J = 7.9, 4.0 Hz, 2H), 4.45 (d, J = 8.1 Hz, 1H), 4.18 (d, J = 11.1 Hz, 2H), 3.88(dt, J = 12.4, 2.3 Hz, 16H), 3.78 – 3.63 (m, 27H), 3.59 – 3.39 (m, 38H), 3.38 – 3.34 (m, 4H), 3.34 – 3.30 (m, 3H), 3.29 – 3.25 (m, 2H), 2.97 (t, J = 7.4Hz, 2H), 1.69 – 1.60 (m, 4H), 1.42 (p, J = 7.6, 7.2 Hz, 2H). 13 C NMR (151 MHz,D2O) δ 102.8, 102.5, 101.9, 83.9, 76.0, 75.8, 75.6, 73.4, 73.2, 73.1, 72.9,70.1, 69.5, 68.1, 60.6, 39.3, 28.1, 26.3, 22.0. ESI-HRMS calcd forC89H154NO71+ [M+H] + 2372.8465, found 2372.9291. Example 7: Synthesis of compound BG-6 Starting from PBG-1, the white powder BG-6 (7 mg, 21%) was obtained by feeding according to the general method B, F (compound 29 as donor), D, E, G.

[0062]

[0063] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.78 – 4.74 (m, 9H), 4.57 – 4.51(m, 4H), 4.50 (d, J= 8.1 Hz, 1H), 4.26 – 4.19 (m, 4H), 3.93 (dt, J = 12.4,2.4 Hz, 12H), 3.87 (dd, J = 10.7, 5.0 Hz, 4H), 3.83 – 3.68 (m, 23H), 3.65 – 3.44 (m, 38H), 3.44 – 3.29 (m, 10H), 3.03 – 2.99 (m, 2H), 1.73 – 1.65 (m, 4H), 1.50 – 1.44 (m, 2H). 13 C NMR (151 MHz, D2O) δ 102.9, 102.8, 102.5, 97.9,84.1, 76.0, 75.6, 74.9, 73.4, 73.3, 70.1, 69.6, 69.4, 68.2, 66.8, 65.0, 60.7,53.3, 52.7, 42.5, 39.4, 28.2, 26.4, 22.1. ESI-HRMS calcd for C89H154NO71+ [M+H] + 2372.8465, found 2372.9133. Example 8: Synthesis of compound BG-7 Starting from PBG-1, feed was carried out according to general methods B, C, E, and G to obtain white powder BG-7 (10 mg, 51%).

[0064]

[0065] 1 H NMR (600 MHz, Deuterium Oxide) δ 7.25 – 7.19 (m, 9H), 6.99 – 6.96(m, 2H), 6.93 (d, J = 8.0 Hz, 1H), 6.66 (d, J = 9.8 Hz, 2H), 6.41 – 6.31 (m,14H), 6.26 – 6.11 (m, 24H), 6.07 – 5.88 (m, 33H), 5.88 – 5.78 (m, 6H), 5.75(dd, J = 9.4, 7.9 Hz, 2H), 5.45 (t, J= 7.6 Hz, 2H), 4.18 – 4.09 (m, 4H), 3.94 – 3.87 (m, 2H). 13 C NMR (151 MHz, D2O) δ 102.8, 102.8, 102.6, 102.5,101.9, 84.6, 84.4, 84.2, 84.0, 83.8, 76.0, 75.8, 75.6, 75.6, 75.5, 75.5,74.5, 73.4, 73.3, 73.2, 73.2, 73.1, 73.0, 72.9, 70.1, 69.5, 68.7, 68.1, 68.1,68.1, 68.0, 60.7, 60.6, 39.3, 28.1, 26.4, 22.0. ESI-HRMS calcd for C77H134NO61+ [M+H] + 2048.7409, found 2048.6630. Example 9: Synthesis of compound BG-8 Starting from PBG-1, feed was performed according to the general procedure B, C, F (with compound 28 as the donor), and G to obtain white powder BG-8 (9 mg, 43%).

[0066]

[0067] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.65 (m, J = 7.5, 2.5 Hz, 13H), 4.45 (d, J = 7.9 Hz, 2H), 4.38 (d, J = 8.1 Hz, 1H), 4.12 (d, J = 11.3 Hz, 2H), 3.82 (d, J = 12.7 Hz, 16H), 3.64 (m, J = 17.8, 8.4 Hz, 32H), 3.42 (m, J = 28.6, 25.6, 14.5, 7.5 Hz, 44H), 3.32 – 3.23 (m, 6H), 2.90 (t, J = 7.6 Hz, 2H), 1.59 (m, J = 13.6, 6.8 Hz, 4H), 1.35 (m,J = 8.0 Hz, 2H); 13 C NMR (151MHz, D2O) δ 102.82, 102.79, 102.64, 102.59, 102.5, 101.9, 84.7, 84.4, 84.3,84.2, 84.1, 76.0, 75.6, 75.54, 75.47, 74.4, 73.4, 73.2, 72.94, 72.89, 70.1,69.6, 68.9, 68.09, 68.07, 60.7, 39.3, 28.1, 26.4, 22.1. ESI-HRMS calcd forC 101 H 174 NO 81 [M+H] + 2696.9522, found 2696.9500. Example 10: Synthesis of compound BG-9 Starting from PBG-1, feed was performed according to the general procedure B, C, F (compound 29 as donor), and G to obtain white powder BG-6 (9 mg, 48%).

[0068]

[0069] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.72 (m, 9H), 4.52 (d, J =7.9 Hz, 2H), 4.48 (dd, J = 8.0, 6.6 Hz, 4H), 4.45 (d, J = 8.1 Hz, 1H), 4.24 –4.15 (m, 6H), 3.89 (dq, J = 12.4, 2.7 Hz, 11H), 3.83 (dt, J = 11.4, 5.6 Hz,7H), 3.79 – 3.64 (m, 24H), 3.62 – 3.40 (m, 47H), 3.39 – 3.33 (m, 4H), 3.33 –3.26 (m, 7H), 2.97 (t, J = 7.6 Hz, 2H), 1.65 (dp, J = 13.3, 7.1, 6.6 Hz, 4H),1.43 (p,J = 7.7 Hz, 2H). 13 C NMR (151 MHz, D2O) δ 103.0, 103.0, 102.9, 102.9,102.8, 102.5, 101.9, 84.7, 84.4, 84.2, 84.0, 84.0, 83.8, 76.0, 75.9, 75.6,75.6, 75.5, 75.5, 75.5, 74.9, 74.9, 73.4, 73.3, 73.1, 73.0, 73.0, 72.9, 70.1,69.6, 69.5, 69.5, 69.4, 68.6, 68.1, 68.0, 60.7, 39.3, 28.1, 26.4, 22.0.ESI-HRMS calcd for C101H174NO81+ [M+H] + 2696.9522, found 2696.9120. Example 11: Synthesis of compound BG-10 Starting from PBG-1, feed was performed according to general methods B, F (compound 28 as donor), D, E, G, to obtain white powder BG-10 (5 mg, 22%).

[0070]

[0071] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.75 – 4.68 (m, 9H), 4.50 (dd, J = 11.9, 8.2 Hz, 2H), 4.44 (d, J = 8.1 Hz, 1H), 4.17 (d, J = 13.0 Hz, 2H),3.91 – 3.81 (m, 17H), 3.77 – 3.62 (m, 30H), 3.58 – 3.39 (m, 42H), 3.36 (t, J = 9.5 Hz, 3H), 3.31 (td, J = 8.7, 8.0, 3.5 Hz, 3H), 3.26 (d, J = 7.6 Hz, 1H), 2.96 (t, J = 7.2 Hz, 2H), 1.64 (tq, J= 14.6, 6.4 Hz, 4H), 1.41 (dt, J =12.2, 5.8 Hz, 2H). 13 C NMR (151 MHz, CDCl3) δ 105.6, 105.4, 105.3, 105.0,104.5, 87.3, 87.0, 86.8, 86.6, 86.4, 78.5, 78.5, 78.2, 78.1, 77.5, 77.1,76.0, 75.8, 75.7, 75.6, 75.4, 72.6, 72.2, 72.1, 72.0, 72.0, 71.5, 71.2, 70.7,70.6, 63.2, 41.9, 30.7, 28.9, 24.6.ESI-HRMS calcd for C89H154NO71+ [M+H] + 2372.8465, found 2372.9039. Example 12: Synthesis of compound BG-11 Starting from PBG-1, the mixture was fed according to general methods A, F (with compound 29 as the donor), D, E, and G to obtain a white powder BG-11 (8 mg, 33%).

[0072]

[0073] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.71 (m, 9H), 4.51 – 4.45 (m, 4H), 4.44 (d, J = 8.1 Hz, 1H), 4.18 (dd, J = 15.9, 11.3 Hz, 4H), 3.91 –3.84 (m, 13H), 3.84 – 3.80 (m, 4H), 3.77 – 3.61 (m, 26H), 3.60 – 3.38 (m,43H), 3.37 – 3.23 (m, 10H), 2.95 (t, J = 7.6 Hz, 2H), 1.63 (dp, J = 13.2,7.1, 6.6 Hz, 4H), 1.41 (p, J = 7.7 Hz, 2H). 13C NMR (151 MHz, D2O) δ 103.0,103.0, 102.9, 102.8, 102.8, 102.6, 102.5, 102.5, 101.9, 101.9, 84.7, 84.0,76.0, 75.9, 75.9, 75.6, 75.6, 75.6, 74.9, 74.5, 73.4, 73.3, 73.1, 73.1, 73.0,72.9, 70.1, 69.6, 69.6, 69.4, 68.6, 68.1, 68.1, 68.0, 60.7, 39.3, 28.1, 26.4,22.1. ESI-HRMS calcd for C89H154NO71+ [M+H] + 2372.8465, found 2372.8713. Example 13: Synthesis of compound BG-12 Starting from PBG-1, feed was performed according to general methods B, D, E, and G to obtain white powder BG-12 (7 mg, 36%).

[0074]

[0075] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.69 (m, 9H), 4.49 (dd, J = 7.9, 2.6 Hz, 2H), 4.44 (dd, J = 8.1, 2.7 Hz, 1H), 4.17 (d, J = 10.4 Hz,2H), 3.92 – 3.81 (m, 14H), 3.78 – 3.61 (m, 24H), 3.58 – 3.39 (m, 34H), 3.38 –3.29 (m, 5H), 3.26 (t, J = 8.8 Hz, 2H), 2.96 (t, J = 7.4 Hz, 2H), 1.64 (dh, J = 12.5, 6.9, 6.4 Hz, 4H), 1.47 – 1.36 (m, 2H). 13C NMR (151 MHz, D2O) δ 102.7,102.6, 102.5, 101.9, 84.6, 84.3, 84.1, 83.9, 83.7, 75.9, 75.8, 75.5, 74.5,73.4, 73.3, 73.2, 73.1, 73.0, 72.9, 70.0, 69.5, 68.7, 68.1, 68.0, 60.6, 39.3,28.1, 26.3, 22.0.ESI-HRMS calcd for C77H134NO61+ [M+H] + 2048.7409, found2048.7907 Example 14: Synthesis of compound BG-13 Starting from PBG-1, the mixture was fed according to the general procedure B, D, F (with compound 28 as the donor), and G to obtain a white powder BG-13 (4 mg, 37%).

[0076]

[0077] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.78 – 4.74 (m, 13H), 4.56 (d, J = 8.1 Hz, 2H), 4.49 (d, J = 8.1 Hz, 1H), 4.23 (d, J = 10.1 Hz, 2H), 3.96 –3.88 (m, 20H), 3.82 – 3.67 (m, 36H), 3.63 – 3.45 (m, 52H), 3.43 – 3.34 (m,7H), 3.01 (t, J = 7.7 Hz, 2H), 1.72 – 1.65 (m, 4H), 1.49 – 1.44 (m, 2H). 13 CNMR (151 MHz, D2O) δ 102.8, 102.5, 101.9, 84.3, 76.0, 75.6, 75.6, 75.5, 73.5,73.2, 73.0, 69.6, 68.1, 60.7, 39.4, 36.1, 28.2, 26.4, 22.1.ESI-HRMS calcd forC 101 H 174 NO 81+ [M+H] + 2696.9522, found 2696.9501. Example 15: Synthesis of compound BG-14 Starting from PBG-1, the mixture was fed according to the general procedure B, D, F (with compound 29 as the donor), and G to obtain a white powder BG-14 (5 mg, 39%).

[0078]

[0079] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.55 – 4.47 (m, 1H), 3.90 (dt, J = 12.5, 2.6 Hz, 7H), 3.84 (dt, J = 11.4, 5.6 Hz, 12H), 3.80 – 3.64 (m, 16H), 3.63 – 3.41 (m, 40H), 3.41 – 3.27 (m, 6H). 13 C NMR (101 MHz, D2O) δ 103.0,102.9, 102.8, 102.5, 101.9, 84.7, 84.4, 84.2, 84.0, 76.0, 75.9, 75.64, 75.59,75.5, 74.9, 74.5, 73.4, 73.3, 73.2, 73.12, 73.05, 73.0, 72.9, 70.1, 69.60,69.55, 69.5, 69.4, 68.8, 68.6, 68.13, 68.06, 60.7, 39.3, 28.1, 26.4,22.1.ESI-HRMS calcd for C 101 H 174 NO 81 + [M+H] + 2696.9522, found 2696.9480. Example 16: Synthesis of compound BG-15 Starting from PBG-1, the mixture was fed according to general methods A, F (with compound 28 as the donor), D, E, and G to obtain a white powder BG-15 (2 mg, 25%).

[0080]

[0081] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.70 (m, 12H), 4.52 (dd, J = 11.9, 7.9 Hz, 2H), 4.46 (d, J = 8.1 Hz, 1H), 4.22 – 4.17 (m, 2H), 3.93 –3.85 (m, 15H), 3.79 – 3.64 (m, 27H), 3.60 – 3.42 (m, 40H), 3.40 – 3.31 (m,6H), 3.28 (dd, J = 9.4, 7.9 Hz, 1H), 2.98 (t, J = 7.6 Hz, 2H), 1.72 – 1.61(m, 4H), 1.43 (p, J = 7.6 Hz, 2H); 13 C NMR (151 MHz, D2O) δ 102.82, 102.78,102.63, 102.59, 102.58, 102.5, 101.9, 84.8, 84.7, 84.4, 84.30, 84.26, 84.1,84.01, 84.0, 75.99, 75.9, 75.61, 75.58, 75.56, 75.55, 75.54, 75.49, 75.48,74.5, 73.4, 73.28, 73.25, 73.2, 73.1, 73.04, 72.97, 72.93, 72.89, 70.1, 69.6,68.9, 68.7, 68.14, 68.06, 60.7, 39.3, 28.1, 26.4, 22.1; ESI-HRMS calcd forC 89 H 154 NO 71 [M+H]+ 2372.8645, found 2372.8660. Example 17: Synthesis of compound BG-16 Starting from PBG-1, the compound was fed according to the general method C, F (compound 28 as donor), B, F (compound 29 as donor), G to obtain white powder BG-16 (2 mg, 20%).

[0082]

[0083] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.62 (d, J = 20.7 Hz, 11H), 4.44– 4.40 (m, 4H), 4.35 (s, 1H), 4.09 (s, 4H), 3.80 (s, 14H), 3.74 (d, J = 11.4Hz, 6H), 3.67 – 3.57 (m, 62H), 3.46 – 3.35 (m, 69H), 3.25 – 3.20 (m, 6H), 2.87 (s, 2H), 1.60 – 1.51 (m, 4H), 1.36 – 1.29 (m, 2H). 13 C NMR (151 MHz, D2O)δ 102.8, 102.5, 97.7, 95.2, 82.7, 78.9, 76.0, 75.5, 73.4, 73.2, 73.1, 73.0,72.8, 69.5, 68.0, 61.9, 60.6, 39.4, 30.1, 25.4, 23.5.ESI-HRMS calcd forC 101 H 174 NO 81 + [M+H] + 2696.9522, found 2696.9556 Example 18: Synthesis of compound BG-17 Starting from PBG-1, feed was performed according to general methods A, D, E, and G to obtain white powder BG-17 (7 mg, 44%).

[0084]

[0085] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.71 (m, 9H), 4.50 (d, J =8.0 Hz, 2H), 4.46 (d, J = 8.1 Hz, 1H), 4.18 (d, J= 10.0 Hz, 2H), 3.92 – 3.84(m, 13H), 3.79 – 3.63 (m, 23H), 3.59 – 3.39 (m, 32H), 3.39 – 3.30 (m, 5H), 3.30 – 3.25 (m, 2H), 2.97 (t, J = 7.6 Hz, 2H), 1.65 (hept, J = 7.0 Hz, 4H), 1.43 (p, J = 7.7, 7.1 Hz, 2H). 13 C NMR (151 MHz, D2O) δ 102.8, 102.5, 101.9,84.6, 84.4, 84.0, 76.0, 75.8, 75.6, 74.5, 73.4, 73.3, 73.1, 73.0, 72.9, 70.1,69.5, 68.7, 68.1, 68.0, 60.7, 39.3, 28.1, 26.4, 22.0.ESI-HRMS calcd forC 77 H 134 NO 61 + [M+H] + 2048.7409, found 2048.7603 Example 19: Synthesis of compound BG-18 Starting from PBG-1, the mixture was fed according to general methods A, D, F (with compound 28 as the donor) and G to obtain white powder BG-18 (3 mg, 21%).

[0086]

[0087] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.69 (m, 13H), 4.51 (m,2H), 4.46 – 4.44 (m, 1H), 4.18 (m, 2H), 3.88 (d, J = 12.1 Hz, 19H), 3.79 –3.62 (m, 34H), 3.60 – 3.40 (m, 47H), 3.40 – 3.35 (m, 3H), 3.35 – 3.29 (m,4H), 2.96 (t, J= 7.1 Hz, 2H), 1.67 – 1.61 (m, 4H), 1.42 (m, 2H). 13 C NMR (151MHz, D2O) δ 111.1, 108.4, 107.0, 102.8, 102.5, 101.4, 101.1, 99.2, 84.1,79.2, 76.02, 76.0, 75.6, 73.4, 73.4, 73.2, 69.5, 68.6, 68.0, 64.9, 60.6,50.3, 39.3, 39.3, 36.7, 32.0, 30.1, 26.3, 25.8, 22.0, 22.0. ESI-HRMS calcdfor C101H174NO81+ [M+H] + 2696.9522, found 2696.9628 Example 20: Synthesis of compound BG-19 Starting from PBG-1, the mixture was fed according to general methods A, D, F (with compound 29 as the donor) and G to obtain white powder BG-19 (5 mg, 35%).

[0088]

[0089] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.68 (m, 13H), 4.53 (d, J = 8.0 Hz, 2H), 4.50 (t, J = 7.2 Hz, 4H), 4.47 (d, J = 8.1 Hz, 1H), 4.20 (t, J = 14.2 Hz, 6H), 3.90 (d, J = 12.3 Hz, 12H), 3.84 (dt, J = 11.3, 5.5 Hz, 6H), 3.80 – 3.65 (m, 24H), 3.63 – 3.42 (m, 45H), 3.41 – 3.27 (m, 11H), 2.99 (t, J = 7.5 Hz, 2H), 1.66 (dp, J = 13.5, 7.2, 6.7 Hz, 4H), 1.44 (p, J= 7.8 Hz, 2H); 13 C NMR (151 MHz, D2O) δ 103.0, 102.9, 102.5, 101.9, 84.0, 75.9, 75.6,75.5, 74.9, 73.3, 73.1, 69.6, 69.4, 68.13, 68.05, 60.7, 39.3, 28.1, 26.4,22.1; ESI-HRMS calcd for C 101 H 174 NO 81 [M+H] + 2696.9522, found 2696.9507. Example 21: Synthesis of compound BG-20 Starting from PBG-1, the compound was fed according to the general method C, F (compound 28 as donor), A, F (compound 29 as donor), G to obtain white powder BG-20 (5 mg, 39%).

[0090]

[0091] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.73 (m, 11H), 4.53 (d, J = 7.9 Hz, 2H), 4.50 (t, J = 7.4 Hz, 2H), 4.47 (d, J = 8.1 Hz, 1H), 4.24 –4.17 (m, 4H), 3.94 – 3.87 (m, 15H), 3.84 (dt, J = 11.5, 5.9 Hz, 4H), 3.80 –3.65 (m, 30H), 3.63 – 3.42 (m, 50H), 3.40 – 3.28 (m, 9H), 2.98 (t, J = 7.5Hz, 2H), 1.66 (dt, J = 14.9, 7.5 Hz, 4H), 1.44 (p, J = 8.0, 7.6 Hz, 2H). 13CNMR (151 MHz, D2O) δ 103.0, 102.9, 102.8, 102.5, 101.9, 84.7, 84.4, 84.1,76.0, 75.9, 75.6, 75.6, 74.9, 74.5, 73.5, 73.3, 73.2, 73.1, 72.9, 70.1, 69.6,69.6, 69.4, 68.9, 68.6, 68.2, 68.1, 60.7, 39.4, 34.1, 28.2, 26.4, 22.1,19.8.ESI-HRMS calcd for C101H174NO81+ [M+H] + 2696.9522, found 2696.9724 Example 22: Synthesis of compound BG-21 Starting from PBG-1, the compound was fed according to the general method D, F (compound 28 as donor), A, F (compound 29 as donor), G to obtain white powder BG-21 (4 mg, 38%).

[0092]

[0093] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.71 (m, 13H), 4.52 (m,2H), 4.49 (m, 2H), 4.46 (d, J = 8.1 Hz, 1H), 4.23 – 4.15 (m, 4H), 3.94 – 3.86(m, 13H), 3.83 (dt, J = 11.7, 5.8 Hz, 3H), 3.78 – 3.64 (m, 26H), 3.62 – 3.41(m, 44H), 3.39 – 3.35 (m, 3H), 3.34 – 3.27 (m, 5H), 2.97 (t, J = 7.8 Hz, 2H), 1.70 – 1.62 (m, 4H), 1.43 (m, 2H). 13C NMR (151 MHz, D2O) δ 103.0, 102.9,102.8, 102.6, 102.5, 101.9, 101.4, 84.2, 84.0, 76.0, 75.9, 75.6, 75.5, 74.9,73.4, 73.3, 73.1, 73.0, 72.9, 70.1, 69.6, 69.5, 68.8, 68.1, 68.0, 60.7, 49.5,45.3, 44.9, 41.4, 39.3, 37.0, 35.9, 29.4, 28.1, 26.4, 22.0. ESI-HRMS calcdfor C101H174NO81+ [M+H] + 2696.9522, found 2696.9609 Example 23: Synthesis of compound BG-22 Starting from PBG-1, feed was carried out according to general methods B, C, E, A, E, G to obtain white powder BG-22 (8 mg, 31%).

[0094]

[0095] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.65 – 4.60 (m, 9H), 4.38 (d, J =8.0 Hz, 3H), 4.33 (d, J = 8.0 Hz, 1H), 4.06 (d, J = 10.7 Hz, 3H), 3.81 – 3.71(m, 17H), 3.67 – 3.50 (m, 27H), 3.48 – 3.27 (m, 38H), 3.27 – 3.21 (m, 6H), 3.21 – 3.13 (m, 5H), 2.85 (t, J = 7.9 Hz, 2H), 1.53 (dq, J = 14.7, 7.0 Hz, 4H), 1.34 – 1.26 (m, 2H). 13C NMR (151 MHz, D2O) δ 105.2, 102.8, 102.6, 102.5,101.9, 84.6, 84.3, 84.0, 83.7, 76.0, 75.8, 75.6, 74.5, 73.4, 73.3, 73.1,73.0, 72.9, 70.1, 69.5, 68.7, 68.1, 68.0, 60.7, 39.3, 28.1, 26.4, 22.0. ESI-HRMS calcd for C83H144NO66+ [M+H] + 2210.7937, found 2210.7540. Example 24: Synthesis of compound BG-23 Starting from PBG-1, the mixture was fed according to general methods B, C, F (compound 29 as donor), A, F (compound 29 as donor), and G to obtain white powder BG-23 (4 mg, 25%).

[0096] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.69 (d, 9H), 4.51 (d, J =7.9 Hz, 3H), 4.49 – 4.46 (m, 6H), 4.45 (d, J = 8.0 Hz, 1H), 4.19 (t, J = 14.3Hz, 9H), 3.88 (d, J = 12.4 Hz, 12H), 3.83 (dt, J = 11.6, 5.7 Hz, 9H), 3.77 –3.64 (m, 25H), 3.60 – 3.41 (m, 56H), 3.36 (t, J = 9.3 Hz, 5H), 3.32 (d, J =8.9 Hz, 1H), 3.30 – 3.26 (m, 9H), 2.97 (t, J = 7.6 Hz, 2H), 1.65 (dp, J =13.4, 7.2, 6.7 Hz, 4H), 1.42 (p, J = 7.9 Hz, 2H); 13C NMR (151 MHz, D2O) δ103.0, 102.9, 102.5, 101.9, 100.3, 75.9, 75.6, 75.5, 74.9, 73.3, 73.12,73.10, 73.08, 73.03, 73.0, 69.6, 69.44, 69.35, 68.6, 68.1, 60.7, 39.3, 28.1,26.4, 22.0; ESI-HRMS calcd for C 119 H 204 NO 96 [M+H] + 3183.1106, found 3183.1125. Example 25: Synthesis of compound BG-24 Starting from PBG-1, following general procedures B, C, F (compound 29 as donor), A, D, E, G, the white powder BG-24 (2 mg, 15%) was obtained:

[0097] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 (d, J = 7.6 Hz, 9H), 4.51 –4.45 (m, 9H), 4.44 (d, J = 8.1 Hz, 1H), 4.16 (d, J = 12.5 Hz, 9H), 3.89 –3.86 (m, 10H), 3.81 (dt, J = 11.1, 5.5 Hz, 9H), 3.76 – 3.63 (m, 30H), 3.59 –3.39 (m, 57H), 3.35 (t, J = 8.8 Hz, 6H), 3.31 (d, J = 8.9 Hz, 2H), 3.26 (dt, J = 10.6, 7.3 Hz, 10H), 2.95 (t, J = 7.6 Hz, 2H), 1.63 (dp, J = 13.3, 7.1,6.7 Hz, 4H), 1.41 (p, J = 7.8 Hz, 2H); 13C NMR (151 MHz, D2O) δ 103.0, 102.88,102.87, 102.85, 102.82, 102.77, 102.7, 102.63, 102.59, 102.57, 102.55,102.54, 102.52, 76.0, 75.99, 75.90, 75.85, 75.83, 75.81, 75.7, 75.58, 75.55,75.54, 75.52, 75.50, 74.93, 74.90, 74.89, 74.54, 74.52, 73.14, 73.06, 69.6,68.60, 68.1, 60.7, 39.3, 28.1, 26.4, 22.1; ESI-HRMS calcd for C 114 H 194 NO 91 [M+H] + 3021.0578, found 3021.0602. Example 26: Synthesis of compound BG-25 Starting from PBG-1, the mixture was fed according to general methods B, F (with compound 28 as the donor), A, C, E, and G to obtain white powder BG-25 (4 mg, 23%).

[0098]

[0099] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.68 (m, 11H), 4.51 (d, J = 8.0 Hz, 1H), 4.49 (d, J = 7.9 Hz, 2H), 4.44 (d, J = 8.1 Hz, 1H), 4.18 (d, J = 11.4 Hz, 3H), 3.88 (ddd, J = 10.3, 4.4, 2.2 Hz, 16H), 3.78 – 3.62 (m, 28H), 3.57 – 3.39 (m, 39H), 3.36 (t, J = 9.1 Hz, 4H), 3.33 – 3.29 (m, 2H), 3.26(dd, J = 9.4, 8.0 Hz, 2H), 2.96 (t,J = 7.6 Hz, 2H), 1.63 (dq, J = 13.4, 7.2,6.7 Hz, 4H), 1.42 (p, J = 7.8 Hz, 2H); 13 C NMR (151 MHz, D2O) δ 102.7, 102.61,102.57, 102.55, 102.53, 102.48, 101.9, 84.68, 84.65, 84.6, 84.33, 84.27,84.0, 83.9, 83.8, 76.0, 75.8, 75.59, 75.59, 75.54, 75.53, 75.45, 74.5, 73.4,73.3, 73.18, 73.15, 73.13, 73.11, 73.09, 73.01, 73.01, 72.94, 72.93, 72.91,72.87, 70.1, 69.5, 68.0, 60.7, 39.3, 28.1, 26.4, 22.0; ESI-HRMS calcd forC 95 H 164 NO 76 [M+H] + 2534.8993, found 2534.9011. Example 27: Synthesis of compound BG-26 Starting from PBG-1, feed was performed according to general method B, H, G to obtain white powder BG-26 (6 mg, 65%).

[0100]

[0101] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.77 – 4.71 (m, 9H), 4.45 (d, J =8.2 Hz, 1H), 4.32 (d, J = 9.8 Hz, 1H), 4.19 (dd, J = 11.1, 5.4 Hz, 1H), 3.88(dt, J = 12.4, 2.4 Hz, 10H), 3.79 – 3.64 (m, 20H), 3.58 – 3.40 (m, 29H), 3.36(t, J= 9.5 Hz, 1H), 3.34 – 3.30 (m, 1H), 2.97 (t, J = 7.6 Hz, 2H), 1.65 (td, J = 14.8, 14.3, 6.8 Hz, 4H), 1.45 – 1.39 (m, 2H). 13 C NMR (151 MHz, D2O) δ102.8, 102.5, 102.5, 101.9, 84.6, 84.4, 84.1, 83.9, 83.5, 77.5, 75.9, 75.6,75.5, 75.5, 73.4, 73.2, 73.1, 72.8, 70.0, 69.5, 68.1, 68.0, 67.7, 67.0, 60.6,39.3, 28.1, 26.4, 22.0.ESI-HRMS calcd for C61H104NO54S- [M] - 1746.5149, found1746.4563. Example 28: Synthesis of compound BG-27 Starting from PBG-1, feed was carried out according to general methods B, C, E, A, D, E, G to obtain white powder BG-27 (4 mg, 43%).

[0102]

[0103] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.78 – 4.72 (m, 9H), 4.51 (d, J =8.0 Hz, 4H), 4.46 (d, J = 8.1 Hz, 1H), 3.91 – 3.85 (m, 15H), 3.80 – 3.64 (m,28H), 3.60 – 3.41 (m, 38H), 3.40 – 3.31 (m, 8H), 3.28 (dd, J = 9.5, 8.0 Hz, 4H), 2.98 (t, J = 7.6 Hz, 2H), 1.66 (dp, J = 13.3, 7.1, 6.6 Hz, 4H), 1.44 (p, J = 7.8 Hz, 2H); 13C NMR (151 MHz, D2O) δ 102.7, 102.6, 102.54, 102.49,102.46, 101.9, 84.6, 84.3, 83.7, 76.0, 75.8, 75.54, 75.50, 74.48, 74.48,73.4, 73.2, 73.1, 73.0, 70.1, 69.5, 68.7, 68.1, 68.02, 68.0, 60.7, 39.3,28.1, 26.4, 22.0; ESI-HRMS calcd for C 89 H 154 NO 71 [M+H] + 2374.1465, found2374.1488. Example 29: Synthesis of compound BG-28 Starting from PBG-1, feed was carried out according to the general procedure B, C, F (compound 28 as donor), A, D, F (compound 28 as donor), G, to obtain white powder BG-28 (5 mg, 24%).

[0104]

[0105] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.71 (d, J = 9.2 Hz, 17H), 4.52(d, J = 8.1 Hz, 4H), 4.45 (d, J = 7.9 Hz, 1H), 4.19 (d, J = 11.4 Hz, 4H), 3.89 (d, J = 12.5 Hz, 23H), 3.71 (tt, J = 17.9, 10.5 Hz, 46H), 3.58 – 3.43(m, 66H), 3.34 (dt, J = 28.9, 8.7 Hz, 13H), 2.97 (t, J = 7.6 Hz, 1H), 2.49(s, 1H), 1.75 – 1.59 (m, 4H), 1.42 (t, J = 8.1 Hz, 2H); 13C NMR (151 MHz, D2O)δ 102.82, 102.78, 102.63, 102.60, 102.58, 102.5, 76.13, 76.10, 76.08, 76.0,75.9, 75.60, 75.57, 75.53, 75.46, 75.42, 75.41, 73.4, 73.20, 73.18, 73.15,72.9, 69.6, 68.10, 68.09, 68.07, 68.0, 60.7, 60.64, 60.62, 60.59, 37.2, 29.1,26.0, 21.3; ESI-HRMS calcd for C 137 H 234 NO 111 [M+H] + 3669.2691, found 3669.2834. Example 30: Synthesis of compound BG-29 Starting from PBG-1, the compound was fed according to general methods B, C, F (compound 29 as donor), A, D, F (compound 29 as donor), and G to obtain white powder BG-29 (5 mg, 37%).

[0106] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.71 (m, 9H), 4.51 (d, J =8.0 Hz, 4H), 4.48 (dd, J = 7.9, 6.5 Hz, 8H), 4.45 (d, J = 8.1 Hz, 1H), 4.19(t, J = 14.4 Hz, 12H), 3.88 (dd, J = 12.4, 2.2 Hz, 12H), 3.83 (dt, J = 11.6,5.7 Hz, 13H), 3.78 – 3.63 (m, 28H), 3.61 – 3.40 (m, 65H), 3.36 (t, J = 9.3Hz, 6H), 3.32 (d, J = 8.8 Hz, 1H), 3.30 – 3.26 (m, 13H), 2.97 (t,J = 7.6 Hz, 2H); 13 C NMR (151 MHz, D2O) δ 103.0, 102.9, 102.82, 102.75, 102.53, 102.46,101.9, 75.9, 75.6, 75.52, 75.50, 75.49, 75.45, 75.4, 74.88, 74.86, 74.8,73.1, 73.02, 73.0, 69.6, 69.5, 69.42, 69.35, 69.32, 69.31, 60.7, 39.3, 28.1,26.4, 22.0; ESI-HRMS calcd for C 137 H 234 NO 111 [M+H] + 3669.2691, found 3669.2755. Example 31: Synthesis of compound BG-31 Starting from PBG-1, feed was performed according to the general method B, C, H, G to obtain white powder BG-31 (4 mg, 60%):

[0107] 1 H NMR (600 MHz, Deuterium Oxide) δ 4.76 – 4.71 (m, 9H), 4.44 (d, J =8.1 Hz, 1H), 4.31 (d, J = 11.0 Hz, 2H), 4.19 (d, J = 4.7 Hz, 2H), 3.88 (d, J = 12.4 Hz, 9H), 3.78 – 3.64 (m, 23H), 3.57 – 3.40 (m, 32H), 3.38 – 3.34 (m,1H), 3.31 (t, J = 8.6 Hz, 1H), 2.96 (t, J = 7.3 Hz, 2H), 1.65 (dq, J = 14.6, 7.3 Hz, 4H), 1.43 (d, J = 7.0 Hz, 2H); 13C NMR (151 MHz, D2O) δ 102.8, 102.64,102.62, 102.60, 102.57, 102.56, 102.54, 102.52, 102.47, 101.9, 75.9, 75.61,75.57, 75.56, 75.52, 75.49, 73.4, 73.28, 73.26, 73.24, 73.22, 73.15, 73.14,73.08, 73.07, 70.0, 69.54, 69.53, 68.12, 68.06, 68.0, 60.6, 56.9, 39.3, 28.1,26.4, 22.3, 22.1; ESI-HRMS calcd for C 65 H 111 NO 57 S2 [M] 2- 940.7635, found 940.7633. Experimental Example 1: Synthetic Compounds Inducing Macrophage Cytokine Expression RAW264.7 cells were planted at a density of 1 × 10⁶ cells per well. 6 Cells were seeded at a density of 100 μM and 10 μM in 96-well plates, and treated with the working solution of the compound to achieve final compound concentrations of 100 μM and 10 μM, respectively. The final concentrations of lipopolysaccharide (LPS) were set at 100 ng / mL, 10 ng / mL, 1 ng / mL, and 0.1 ng / mL, while the final concentrations of laminarin (LAM) were 2000 μg / mL, 200 μg / mL, 20 μg / mL, and 2 μg / mL. Cells and the compound of formula I were co-cultured at 37 °C in a 5% CO2 incubator for 24 hours, after which the supernatant was collected. Cytokine levels were detected using a self-coated double-antibody sandwich ELISA system. The absorbance at 450 nm (reference wavelength 630 nm) was measured using a microplate reader, and the concentrations of cytokines TNF-α and IL-6 were calculated accordingly.

[0108] Experimental Example 2: Effects of Synthetic Compounds on Macrophage Phagocytosis RAW264.7 cells were planted at a density of 1 × 10⁶ cells per well. 6Cells were seeded at a density of [number] cells per well in 96-well plates and treated with the working solution of the compound to achieve the final concentration described above. Cells and the compound were co-cultured at 37 °C in a 5% CO2 incubator for 24 hours. Subsequently, fluorescently labeled latex beads were added to a final concentration of 2.5 μL / mL, and the cells were incubated at 37 °C for 2 hours to allow macrophages to phagocytose the fluorescent microspheres. After incubation, the supernatant was removed, and the cells were washed three times with PBS. Finally, 200 μL of PBS was added to each well, and phagocytosis was observed under a fluorescence microscope. The fluorescence intensity was then measured using a microplate reader to quantify phagocytic activity.

[0109] Experiment Example 3: Active compounds enhance NK cell-mediated killing effects Primary NK cells were isolated from the spleen of mouse C57BL / 6 mice and treated by co-incubation with synthetic dextran or a positive control for 24 hours. After incubation, effector NK cells were collected, washed twice with PBS, and then resuspended in RPMI-1640 medium. The cell density was adjusted to 1 × 10⁶ cells / year in RPMI-1640 medium containing 10% FBS. 7 Cells / mL, take 100 μL of the cell suspension and seed it into each well of a 96-well plate.

[0110] For target cells, logarithmically growing Yac-1 cells were labeled with 20 μM Calcein-AM at 37 °C for 30 min. After washing twice with PBS to remove excess dye, the labeled Yac-1 cells were resuspended in RPMI-1640 (containing 10% FBS) and added to effector cells at the specified effector-to-target ratio (E:T ratio). Spontaneous release (negative control) and maximum release (positive control) groups were established by incubating Yac-1 cells with RPMI-1640 and 0.2% Triton X-100, respectively. After co-incubation at 37 °C for 4 hours, 75 μL of the supernatant was transferred to a black-bottomed 96-well plate. Fluorescence intensity was quantified using a microplate reader.

[0111] Results analysis: Different β-glucan samples all showed varying degrees of enhancement effect on macrophage phagocytic function. ELISA detection showed (e.g.) Figure 1 As shown in A~D in the diagram, compounds BG-8, 15, 19, 23, 24, 25, 27, 28, 29, and 30 stimulated the secretion of cytokines TNF-α and IL-6 at both concentrations. These ten compounds were then used to test their effects on macrophage phagocytic capacity.

[0112] Fluorescence microscopy observation shows (e.g.) Figure 2As shown in the figure, macrophages treated with BG-15, 19, 28, and 30 exhibited significantly enhanced internalization under a fluorescence microscope in a concentration-dependent manner. This immunomodulatory effect was further confirmed by assessing NK cell-mediated lysis. A graph was plotted showing the change in NK cell lysis rate (%) as the effector cell to target cell ratio (E:T ratio) decreased (from 50:1 to 6.25:1). The results showed that BG-15, 19, 28, and 30 significantly enhanced NK cell-mediated killing in an E:T ratio-dependent manner (e.g., macrophages treated with BG-15, 19, 28, and 30). Figure 3 (As shown). Notably, at high E:T ratios, the immunomodulatory effects of these synthetic dextrans are comparable to, and even surpass, known immunostimulants such as LPS and LAM. These results suggest that the structure, spacing, and number of the 6-position side chain have a significant impact on immune activity.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A β-1,3-glucan containing an O-6 side chain, characterized in that, The structure is shown in Equation I: ， R1, R2, R3, and R4 are each independently selected from any one of hydrogen, β-linked glucose, β-1,3-linked glucosylbiose, β-1,3-linked glucosyltrisaccharide, β-1,3-linked glucosyltetrasaccharide, β-1,6-linked glucosylbiose, β-1,6-linked glucosyltrisaccharide, β-1,6-linked glucosyltetrasaccharide, sulfonic acid group, and phosphate group.

2. The O-6 side chain containing β-1,3-glucan according to claim 1, characterized in that, In the β-1,3-glucan containing the O-6 side chain, R1, R2, R3 and R4 are each independently selected from any one of hydrogen, β-linked glucose, β-1,3-linked glucosyltrisaccharide, β-1,6-linked glucosyltrisaccharide, and sulfonic acid group.

3. The O-6 side chain containing β-1,3-glucan of claim 2, characterized in that, The β-1,3-glucan containing the O-6 side chain is selected from any of the following structures: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 4. The O-6 side chain containing β-1,3-glucan of claim 3, characterized in that, The β-1,3-glucan containing the O-6 side chain is selected from any of the following structures: 、 、 、 、 、 、 、 、 、 、 。 5. The β-1,3-glucan containing an O-6 side chain according to claim 4, characterized in that, The β-1,3-glucan containing the O-6 side chain is selected from any of the following structures: 、 、 、 。 6. The method for preparing β-1,3-glucan containing an O-6 side chain according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) A one-pot glycosylation reaction was carried out using a trisaccharide trifluoroacetylimine ester donor 1, a tetrasaccharide acceptor 2 containing an o-alkynyl benzoate group and a reducing end trisaccharide acceptor 3 to obtain a decasaccharide skeleton compound PBG-1. (2) Remove the orthogonal protecting group from the decasaccharide skeleton compound PBG-1, and then react it with the donor containing R1, R2, R3 or R4 substituents respectively. Finally, remove the various ester protecting groups under alkaline conditions and remove all benzyl protecting groups by hydrogenation to obtain β-1,3-glucan containing O-6 side chain. The specific reaction route is as follows: 。 7. The method for preparing β-1,3-glucan containing an O-6 side chain according to claim 6, characterized in that, The preparation method of the trisaccharide trifluoroacetylimine ester donor 1, Includes the following steps: Trifluoroacetylimine ester donor 4 was glycosylated with acceptor 5 containing p-toluenethio group at the anomeric position under TMSOTf catalysis to obtain trisaccharide 6. After the acetylpropionyl group of trisaccharide 6 was removed under hydrazine acetate conditions and replaced with Fmoc protecting group, compound 7 was obtained. Compound 7 was hydrolyzed to hemiacetal under trichloroisocyanuric acid conditions, and then reacted with trifluoroacetylimine chloride to prepare donor 1. The specific route is as follows: 。 8. The method for preparing β-1,3-glucan containing an O-6 side chain according to claim 6, characterized in that, The method for preparing the tetrasaccharide receptor 2 containing an o-alkynylbenzoate group, Includes the following steps: Trifluoroacetylimine ester donor 8 and acceptor 5 containing p-toluenethio group at the anodic position are catalyzed by TMSOTf to generate tetrasaccharide 9. After the anodic STol is hydrolyzed to hemiacetal by TCCA, it undergoes a condensation reaction with o-alkynylbenzoic acid to prepare compound 10. After removing the Lev of the tetrasaccharide, it is converted into an Alloc protecting group. The non-reducing end TBS protecting group is removed using a pyridine hydrogen fluoride reagent to obtain acceptor 2 containing o-alkynylbenzoic acid ester group. The specific route is as follows: 。 9. The method for preparing β-1,3-glucan containing an O-6 side chain according to claim 6, characterized in that, The method for preparing the reduced-terminal trisaccharide receptor 3 includes the following steps: The disaccharide trifluoroacetylimine ester donor 11 was used to undergo a glycosylation reaction with a monosaccharide acceptor 12 with a connector. The resulting product was then treated with a pyridine fluoride reagent to obtain a reduced-terminal trisaccharide acceptor 3 with a hydroxyl group exposed at the 3-position. The specific route is as follows: 。 10. The application of β-1,3-glucan containing an O-6 side chain according to any one of claims 1 to 6 in the preparation of immunomodulators.

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