N-acetylgalactosamine modified pentaerythritol derivative for oligonucleotide end capping, preparation method thereof, delivery compound and nucleotide drug

Abstract

The invention relates to the technical field of chemical synthesis, in particular to an oligonucleotide-terminated N-acetylgalactosamine modified pentaerythritol derivative, a preparation method thereof, a delivery compound and a nucleotide drug. The N-acetylgalactosamine modified pentaerythritol ether derivative is selected from compounds shown in the following structural formula: # imgabs0 #, X is H or a hydroxyl protecting group, Y is an amino protecting group, A, B and C are independently selected from linking groups formed by at least one of a hydrogen element, a carbon element, an oxygen element, a sulfur element and a phosphorus element respectively, and D is a linking group for solid-phase synthesis of oligonucleotide. The compound can be used as an end-capping reagent of oligonucleotides, can be bonded with the oligonucleotides, and then can be used for delivering drugs so as to realize RNAi (Ribonucleic Acid Interference) therapy.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and in particular to an N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, a preparation method thereof, a delivery compound and a nucleotide drug. Background Art

[0002] With the accelerated approval and marketing of RNAi therapy in recent years, the popularity of RNAi therapy has gradually risen, and all this is inseparable from the boost of delivery technology. There are two main challenges for siRNA to enter cells: one is that siRNA will have stability problems and cause immunogenicity when exposed to the blood; the other is that large molecular weight negatively charged siRNA cannot cross the membrane and enter the cell by itself. The third-generation delivery solution based on GalNAc (N-acetylgalactose) has solved some problems encountered by the second-generation liposome (LNP) delivery in the field of liver disease with low immunogenicity, low cytotoxicity and high targeting, allowing siRNA to play a big role in liver disease. The principle is that GalNAc has a high affinity for asialoglycoprotein (ASGPR). ASGPR is a large number of hetero-oligomer endocytic receptors that only exist in liver parenchymal cells and can specifically recognize and bind GalNAc. Therefore, GalNAc modification of siRNA can achieve specific delivery of siRNA to the liver, and enable siRNA to enter cells and function through ASGPR-mediated cellular endocytosis.

[0003] After years of continuous research and development, Alnylam, a US company, has made a breakthrough in utilizing the GalNAc / ASGPR drug delivery mechanism. From its public literature and patents, we can see that the distances between the three antennae of the GalNAc-conjugated siRNA molecule it developed are It has a high affinity for ASGPR (dissociation constant (Kd) = 2.7nM). They compared intravenous administration with subcutaneous administration and found that subcutaneous administration was more effective. Based on this GalNAc conjugation drug delivery technology, Alnylam has developed a series of siRNA drug varieties, including ALN-TTRsc (for the treatment of amyloid lesions), ALN-AT3 (for the treatment of hemophilia and rare bleeding disorders), ALN-CC5 (for the treatment of complement-mediated diseases), ALN-AS1 (for the treatment of liver porphyria), ALN-PCSsc (for the treatment of hypercholesterolemia), ALN-HBV (for the treatment of hepatitis B), ALN-AGT (for the treatment of gestational hypertension, including preeclampsia) and other projects. Among the RNA drugs currently approved for marketing, three are based on the delivery of siRNA drugs based on GalNAc coupling technology. The three siRNA drugs on the market were all developed by Alnylam, namely Givosiran, Lumasiran, and Inclisiran. Inclisiran was jointly developed by Alnylam and Novartis. All three products have significant advantages in the treatment of liver-related diseases. After Alnylam successfully industrialized this technology, other siRNA companies, such as Arrowhead and Dicerna, also began to follow this delivery method. For example, the compound shown in the following structural formula:

[0004]

[0005] It can be seen that designing new GalNAc-modified linking groups (end groups of oligo synthesis) or monomers with GalNAc groups is of great significance. However, the design of GalNAc molecules is very difficult from design to finalization due to its complex synthesis, and the designed GalNAc molecules are required to have a good delivery effect.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide an N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping and a preparation method thereof, a delivery compound and a nucleotide drug. The embodiment of the present invention provides a new N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, which can be used to deliver siRNA with good delivery effect and can be used for RNAi treatment.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides an N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, which is selected from the compounds represented by the following structural formula:

[0010] Wherein, X is H or a hydroxyl protecting group, Y is an amino protecting group, A, B and C are independently selected from at least one of hydrogen, carbon, oxygen, sulfur and phosphorus to form a linking group, and D is a linking group for solid phase synthesis of oligonucleotides.

[0011] In a second aspect, the present invention provides a method for preparing an N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping as described in the aforementioned embodiment, comprising: using a terminal alkyne or terminal olefin containing a protective group to carry out a Michael addition reaction to construct three ether bonds; then modifying the protective group to attach a group containing GalNAc;

[0012] Alternatively, a halogen-containing compound is used to carry out an alkylation reaction to construct three ether bonds, and then the protective group above is modified to connect a GalNAc-containing group.

[0013] In a third aspect, the present invention provides a delivery compound capable of achieving drug delivery, comprising a bonding compound and the N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping described in the aforementioned embodiment, wherein the bonding compound and the N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping are connected via their D groups;

[0014] Preferably, the bonding compound is selected from a nucleotide chain or a fluorescent compound.

[0015] In a fourth aspect, the present invention provides a nucleotide drug, which includes the delivery compound capable of achieving drug delivery as described in the aforementioned embodiment.

[0016] The present invention has the following beneficial effects: An embodiment of the present invention provides an N-acetylgalactosamine modified pentaerythritol derivative, which uses pentaerythritol as a matrix, connects three N-acetylgalactosamines with various carbon-carbon bonds and carbon-oxygen bonds, and another ether bond is connected to a functionalized group D through a connecting group formed by a carbon-carbon bond, a carbon-oxygen bond, a carbon-nitrogen bond or a phosphorus-oxygen bond or at least one of other hydrogen, carbon, oxygen, sulfur and phosphorus elements, so that the formed N-acetylgalactosamine modified pentaerythritol derivative can be used as an oligonucleotide capping agent, can be bonded to the oligonucleotide, and then can deliver drugs, thereby realizing RNAi therapy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a diagram of experimental results provided for Experimental Example 1 of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0020] In a first aspect, an embodiment of the present invention provides an N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, which is selected from the compounds represented by the following structural formula:

[0021] Wherein, X is H or a hydroxyl protecting group, Y is an amino protecting group, A, B and C are independently selected from at least one of hydrogen, carbon, oxygen, sulfur and phosphorus to form a linking group, and D is a linking group for solid phase synthesis of oligonucleotides.

[0022] For example, the N-acetylgalactosamine modified pentaerythritol derivative is selected from any one of the compounds shown in the structural formula:

[0023]

[0024] Wherein, in Formula Ia, when LR is used as a group, LR can be selected from H or phosphoramidite; that is, LR is used as a substituent as a whole.

[0025] When L and R are two groups, L is selected from an ester group or an amide bond; R is selected from a group connected to L or a solid phase carrier; that is, L and R represent two different groups respectively.

[0026] Z is selected from a hydroxyl protecting group or H; for example, the hydroxyl protecting group may be a hydroxyl protecting group in the prior art, such as but not limited to 4,4'-dimethoxytriphenylmethyl (DMTr).

[0027] The dotted line in formula Ia may represent a ring structure, in which case L and Any position on the ring; the dotted line in formula Ia represents a chain structure, lie in Any position on the chain.

[0028] In formula Ib, R1 is selected from a phosphoramidite group or a solid phase support.

[0029] Further, it is selected from the compounds shown in the following structural formula:

[0030] Z is selected from a hydroxyl protecting group or H; L is selected from an ester group or an amide bond; and R is selected from a group connected to L or a solid phase carrier.

[0031] Furthermore, the group A is an amide group or an alkyl group; more preferably a C1-C10 amide group and a C1-C15 unsubstituted alkyl group; further preferably a C1-C5 amide group and a C1-C10 unsubstituted alkyl group; more preferably any one of formamide, acetamide, methyl, ethyl and propyl.

[0032] The above group C is an amide group or a triazole; further, n is any value between 1 and 5, for example, n is any value between 1 and 5, such as 1, 2, 3, 4 and 5. The above “—” indicates the position connected to the mother core.

[0033] For example, the compound shown in the following structural formula is used:

[0034]

[0035]

[0036] The group B is selected from an alkyl group or a polyether group; preferably a C1-C20 unsubstituted alkyl group or a polyethylene glycol group of different lengths; more preferably a C1-C10 unsubstituted alkyl group or -(CH2CH2O) m , m is 2-15; most preferably C1-C5 unsubstituted alkyl.

[0037] X and Y are independently selected from acyl groups, preferably C2-C10 acyl groups, including but not limited to acetyl, benzoyl or isopropanoyl.

[0038] Furthermore, it is selected from any one of the compounds represented by the following structural formulas:

[0039]

[0040]

[0041] In a second aspect, an embodiment of the present invention provides a method for preparing the above-mentioned N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, comprising: using a terminal alkyne or terminal olefin containing a protective group to carry out a Michael addition reaction to construct three ether bonds; then modifying the above-mentioned protective group to connect a group containing GalNAc;

[0042] Alternatively, a halogen-containing compound is used to carry out an alkylation reaction to construct three ether bonds, and then the protective group above is modified to connect a GalNAc-containing group.

[0043] The synthesis reaction used in the synthesis route is an existing synthesis reaction, and therefore, the embodiment of the present invention will not be described in detail.

[0044] Specifically, the three ether bonds on the left are constructed in the following ways, including but not limited to:

[0045]

[0046] In a third aspect, an embodiment of the present invention provides a delivery compound capable of achieving drug delivery, comprising a bonding compound and the aforementioned N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, wherein the bonding compound and the N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping are connected via their D groups; that is, the bonding compound reacts with the D group, thereby chemically bonding the bonding compound to the N-acetylgalactosamine-modified pentaerythritol derivative.

[0047] The bonding compound is selected from a nucleotide chain or a fluorescent compound, that is, the nucleotide chain is bonded to an N-acetylgalactosamine-modified pentaerythritol derivative.

[0048] In a fourth aspect, an embodiment of the present invention provides a nucleotide drug, which includes the above-mentioned delivery compound capable of achieving drug delivery.

[0049] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0050] Example 1

[0051] The embodiment of the present invention provides an N-acetylgalactosamine modified pentaerythritol derivative (I1), and its synthesis route is as follows:

[0052]

[0053]

[0054] In this Example 1, compound 1 was used as the starting material and compound I1 was synthesized through 7 steps of reaction. Compound I1 can be used as a modification group of RNA to introduce a GalNAc protective group with pentaerythritol as the backbone. The synthesis process of compound I1 is as follows:

[0055] S1. Synthesis of compound 2:

[0056] Compound 1 pentaerythritol (80 g, 5 eq.) was dissolved in 650 g DMSO, 65 mL 0.5 N NaOH solution was added to the solution, 17 g tert-butyl acrylate (17 g, 1 eq.) was added at once while stirring at 28 °C, and the mixture was stirred at 25±5 °C for 17 hours.

[0057] Post-treatment: Pour the reaction solution into 1300g saturated brine, add THF (300mL*5) for extraction, combine the THF layers, and directly concentrate to obtain 61g of crude product. The crude product is passed through a column with 180g of silica gel, and the column is washed with n-heptane / ethyl acetate 5 / 1 to 1 / 1 (v / v) to obtain 25g of product.

[0058] Compound 2, colorless oil, yield 79%. 1 H NMR (500 MHz, CDCl 3) δ3.69-3.60(m,8H),3.50(s,2H),3.39(s,2H),2.48(t,J=5.9Hz,2H),1.46(s,9H).

[0059] S2. Synthesis of compound 3:

[0060] Compound 2 (25 g, 1 eq.) was dissolved in 300 mL of toluene, 150 g of 10% potassium hydroxide aqueous solution and 0.5 g of TBAB were added to the solution, acrylonitrile (40 g, 8 eq.) was added at 5°C, the temperature was maintained at 5-10°C, and stirred for 5 hours. TLC showed the end point of the reaction.

[0061] Post-treatment: Add 200 mL of water, extract and separate the organic phase, extract the water layer twice with toluene, 150 mL each time, combine the toluene layers, wash twice with water, and concentrate to obtain a crude product. The crude product is passed through a column with 150 g of silica gel, and the column is washed with n-heptane / ethyl acetate 100 / 1 to 10 / 1 (v / v) to obtain 18 g of the product.

[0062] Compound 3, light yellow oil, yield 45%. 1 H NMR (500MHz, CDCl3) δ3.57 (s, 6H), 3.45 (s, 2H), 3.35 (m, 8H), 2.68 (m, 6H), 2.40 (t, J = 6.2Hz, 2H), 1.40 (s, 9H).

[0063] S3, synthesis of compound 4;

[0064] Add 25 mL of methanol to compound 3 (5 g, 1 eq.) to dissolve it, add 16 mL of ammonia water and 16 mL of water, add 10 g (200 w%) of Raney nickel under nitrogen protection at 25 °C, replace the system with hydrogen and set the pressure to 0.8 MPa, stir for 20 hours, and after the reaction is completed, filter, rinse the residue three times with 50 mL of methanol, and concentrate to obtain 4.2 g of oil. The crude product is directly used for the next synthesis.

[0065] S4, synthesis of compound 6;

[0066] To compound 5 (13.2 g, 3.5 eq.) and HOBT (0.6 g, 0.6 eq.) was added 84 mL of DCM and 36 mL of DMF, and the mixture was stirred to dissolve. The system was cooled to 10°C, and DIPEA (18 g, 20.2 eq.) and HBTU (10.4 g, 4.0 eq.) were added. After stirring for 10 minutes, a solution of compound 4 (3 g, 1.0 eq.) in DMF (36 mL) was added, and the reaction was stirred at 25°C for 17 h.

[0067] Post-treatment: Add 180 mL of DCM to the system, then add 270 mL of 5% sodium bicarbonate aqueous solution, stir for 30 minutes, separate the liquids to obtain the DCM layer, wash the organic phase once with 100 mL of saturated brine, dry over anhydrous sodium sulfate, filter, and concentrate to obtain a crude oil. Pass the column through a silica gel column, wash the column with DCM / EA 100 / 1 to 10 / 1 (v / v), and obtain 4.5 g of a white solid.

[0068] Compound 6, white solid, yield 45%. 1 H NMR (500MHz, CDCl3) δ6.53-6.75(m,6H),5.35(s,3H),5.20(m,3H),4.62(m,3H),4.10-4.17(m,19H),3.90-3.93(m,10H),3.29- 3.63(m,36H),2.45(t,J=10Hz,2H),2.14-2.25(m,17H),1.94-2.02(m,19H),1.73-1.78(m,9H),1.60-1.67(m,6H),1.46(s,9H).

[0069] S5. Synthesis of compound 9;

[0070] To compound 6 (4 g, 1 eq.) was added 30 mL of formic acid, and after stirring at 25°C for 6 hours, the formic acid was concentrated to obtain compound 7 which was directly used for the next step.

[0071] 60 mL of DCM was added to compound 7 to dissolve it, and DIPEA (2.4 g, 7.7 eq.), HOBT (0.8 g, 1.5 eq.) and compound 8 (1.6 g, 1.67 eq.) were added in sequence. After stirring for 20 min, EDCI (1.6 g, 3.3 eq.) was added and the reaction was stirred at 25 °C for 17 h.

[0072] Post-treatment: add 60 mL of 5% sodium bicarbonate aqueous solution, stir for 30 min, separate the organic phase, wash once with 60 mL of saturated brine, dry over anhydrous sodium sulfate, filter, and concentrate to obtain a crude oil. C18 preparative separation, obtain 2 g of white solid.

[0073] Compound 9, white solid, yield 50%. 1 H NMR(500MHz,DMSO-d6)δ8.58(m,5H),7.91–7.67(m,8H),7.43–7.14(m,14H),6.95–6.81(m,4H),5.21(d,J=2.8Hz,3H),5.01–4.92(m,3H),4. 49(d,J=8.4Hz,3H),4.02(s,9H),3.88(m,3H),3.78–3.65(m,9H),3.3 1–3.16(m,13H),3.05(m,8H),2.18–1.73(m,45H),1.64–1.36(m,18H).

[0074] S6. Synthesis of compound I1:

[0075] Compound 9 (1 g, 1.0 eq.) was dissolved in 10 mL DCM, TEA (87 mg, 2 eq.) was added to the system, and then the temperature was lowered to 0°C, and then succinic anhydride reagent (64.5 mg, 1.5 eq.) was added to the system, and the reaction was stirred at 25°C for 2 h.

[0076] Post-treatment: add 10 mL of 10% sodium bicarbonate aqueous solution, stir for 30 min, separate the organic phase, wash once with 10 mL of saturated brine, dry over anhydrous sodium sulfate, filter, and concentrate to obtain a crude oil. The crude product is dissolved in DCM and MTBE is added to precipitate, and finally 0.8 g of brown solid is obtained.

[0077] Compound I1, brown solid, yield 50%, purity 99.27%.

[0078] Example 2

[0079] The embodiment of the present invention provides an N-acetylgalactosamine modified pentaerythritol derivative (I2), and its synthesis route is as follows:

[0080]

[0081]

[0082] The synthesis method provided in this embodiment is the same as the synthesis method in Example 1, both of which use compound 1 as the starting material, and compound I2 is synthesized through 8 steps of reaction. Compound I2 can also be used as a modification group of RNA to introduce a GalNAc protective group with pentaerythritol as the backbone. The synthesis of compound I2 is simpler than that of I1, and the yield is higher. Specifically, the synthesis process of I2 is as follows:

[0083] S1. Synthesis of compound 10;

[0084] Compound 2 (26.4 g, 1.0 eq), NMM (40 g, 4.0 eq), and ethyl propiolate (40 g, 3.3 eq) were dissolved in 100 mL DCM and stirred at room temperature for 4.0 hours. The reaction was completed by TLC monitoring.

[0085] The mixture was washed three times with 10% NaCl solution, and the organic phase was dried over anhydrous sodium sulfate, concentrated, and chromatographed on a silica gel column (n-heptane / ethyl acetate 15 / 1-10 / 1) to obtain 46 g of the product.

[0086] Compound 10, colorless oil, yield 82%. 1 H NMR (500MHz, CDCl3) δ7.54 (d, J = 10Hz, 3H), 5.23 (d, J = 15Hz, 3H), 4.16 (t, J = 6.7Hz, 6H), 3.88 (s, 6H), 3.64 (t, J = 5Hz, 2H), 3.49 (s, 2H), 2.45 (t, J = 5Hz, 2H), 1.44 (s, 9H), 1.27 (t, J = 6.25Hz, 9H).

[0087] S2, synthesis of compound 11;

[0088] Compound 10 (46 g, 1.0 eq.) was dissolved in 460 mL of ethyl acetate, and 4.6 g of Pd / C was added. The atmosphere was replaced with nitrogen and then hydrogen. The reaction was carried out at room temperature for 10 hours. The starting material disappeared after TLC detection.

[0089] The reaction solution was filtered, and the filtrate was washed three times with 10% NaCl solution. The organic phase was dried over anhydrous sodium sulfate and concentrated to obtain 47 g of a clean product.

[0090] Compound 11, colorless oil, yield 99%. 1H NMR(500MHz, CDCl3)δ4.14(t,J=6.7Hz,6H),3.58-3.65(m,8H),3.34-3.35(m,8H) ), 2.52 (t, J = 5Hz, 6H), 2.43 (t, J = 5Hz, 2H), 1.45 (s, 9H), 1.27 (t, J = 6.25Hz, 9H).

[0091] S3, synthesis of compound 12;

[0092] Compound 11 (26 g, 1.0 eq.) and 230 mL formic acid were stirred at room temperature for 6 hours. After the formic acid was concentrated, 25 g of crude product was obtained, which was directly used in the next step.

[0093] S4, synthesis of compound 14;

[0094] Compound 12 (25 g, 1.0 eq.) was dissolved in 200 mL DCM, and DIPEA (17.2 g, 3.0 eq.), HOBT (5.94 g, 1.0 eq.) and compound 13 (17.2 g, 1.0 eq.) were added in sequence. After stirring for 20 min, EDCI (10.2 g, 1.2 eq.) was added and stirred at room temperature for 17 hours. The reaction solution was washed twice with NaHCO3 aqueous solution at 0-5°C, and the organic phase was washed twice with 10% NaCl solution. The organic phase was dried over anhydrous sodium sulfate, concentrated, and chromatographed on a silica gel column (n-heptane / ethyl acetate 10 / 1) to obtain 27 g of the product.

[0095] Compound 14, light yellow oil, yield 62%. 1 H NMR (500MHz, DMSO-d6) δ7.20-7.42(m,9H),6.88(d,J=10Hz,4H),4.95(d,J=5Hz,1H),4.02-4.08(m,6H),3.74 (s, 6H), 3.46-3.56 (m, 8H), 3.22-3.24 (m, 8H), 2.86-3.03 (m, 3H), 2.28 (t, J = 5Hz, 2H), 1.18 (t, J = 6.25Hz, 9H).

[0096] S5. Synthesis of compound 15;

[0097] Compound 14 (27 g, 1.0 eq.) was dissolved in 200 mL THF, and LiOH (2 eq.) aqueous solution was added and stirred at room temperature for 6 hours. After the reaction, the temperature was lowered to 0°C, and the pH was adjusted to weak alkalinity with 5% acetic acid solution. The product was directly concentrated to obtain 28 g of crude product, which was directly used for the next step.

[0098] S6, synthesis of compound 17;

[0099] Compound 15 (14 g) was added and dissolved in 140 mL DCM. The temperature was lowered to 0-5 degrees. DIPEA (10 eq.), compound 16 (3.9 eq.), HOBt (0.5 eq.), and EDCI (4 eq.) were added and stirred at room temperature for 14 hours.

[0100] The reaction solution was washed twice with a NaHCO3 aqueous solution at 0-5°C, and the organic phase was washed twice with a 10% NaCl solution. The organic phase was dried over anhydrous sodium sulfate, concentrated, and then reversed to obtain 12 g of the product.

[0101] Compound 17, light yellow oil, yield 33%. 1 H NMR(500MHz,DMSO-d6)δ8.57-8.59(m,7H),7.77-7.84(m,10H),7.25-7.40(m ,16H),6.88(d,J=10Hz,4H),4.96-4.99(m,4H),4.49(d,J=10Hz,3H),3.69-4. 04(m,22H),3.38-3.52(m,11H),3.21(s,8H),2.92-3.04(m,8H),2.25-2.29(m ,7H),2.1(s,9H),1.99(s,9H),1.89(s,9H),1.77(s,9H),1.24-1.46(m,24H).

[0102] S7, synthesis of compound I2;

[0103] Compound 17 (9 g, 1.0 eq.) was dissolved in 100 mL DCM, TEA (2 eq.) was added to the system and the temperature was lowered to 0°C, and then succinic anhydride reagent (1.5 eq.) was added to the system, and the reaction was stirred at 25°C for 2 h.

[0104] Post-treatment: add 10% sodium bicarbonate aqueous solution, stir for 30 minutes, separate the organic phase, wash once with saturated brine, dry over anhydrous sodium sulfate, filter, and concentrate to obtain a crude oil. The crude product is dissolved in DCM and MTBE is added thereto to precipitate, and finally 7g of brown solid is obtained.

[0105] Compound I2, brown solid, yield 74%, purity 99.15%.

[0106] Example 3

[0107] The embodiment of the present invention provides an N-acetylgalactosamine modified pentaerythritol derivative (I3), and the synthesis method thereof is as follows:

[0108] Using compound 18 as the starting material, an important nucleic acid modified end group compound 23 was synthesized through 5 steps of reaction (refer to the following synthesis route). Compound 23 can then be used as a modification group for RNA. After the modified RNA chain is synthesized, it undergoes a click reaction with compound 30 to obtain GalNAc modified nucleic acid I3 with triazole as the connecting group. The synthesis of compound 30 referred to patent WO2020139788A2 and compared with nuclear magnetic resonance data. Compound 30 was synthesized in the embodiment of the present invention. Among them, the structural formula of I3 is as follows:

[0109]

[0110] S1. Synthesis of compound 19:

[0111] Compound 18 (50 g, 1 eq.) was dissolved in 300 mL of DCM, imidazole (2.73 eq.) was added all at once at 0-5°C, TBDPS-Cl (0.91 eq.) was slowly added dropwise, and the mixture was reacted at 25°C for 3.5 h.

[0112] The mixture was filtered through diatomaceous earth, and the organic phase of the filtrate was washed once with 5% NaHCO3 solution, twice with 2% acetic acid aqueous solution, once with 5% NaHCO3 solution, and once with 10% NaCl solution. The organic phase was dried over anhydrous sodium sulfate and concentrated to obtain 102.8 g of an oily substance, which was used directly in the next step.

[0113] S2. Synthesis of compound 20:

[0114] Take compound 19 (102g, 1.0eq.) and concentrate it with DCM to KF 87ppm, then concentrate it to dryness and dissolve it with 120mL DCM. Take compound 1 (165.5g, 5eq.) and dissolve it with 800mL DMSO. Cool the system of compound 1 to 15-20℃, add potassium tert-butoxide (54.4g, 2.0eq.) twice under nitrogen protection, 27.2g each time, and 5-10 minutes interval each time. After adding, heat it to 20-25℃ and stir for 20-25 minutes. Cool the reaction system to 7-13℃, slowly add the qualified F001 solution of CP-A440-M1 with water to the reaction system, and heat it to 20-25℃ and react for 4.5h after adding.

[0115] After the reaction, the reaction system was added dropwise to 8% acetic acid aqueous solution. After stirring for 10 to 15 minutes, the pH of the system was measured. If the pH was 5 to 6, 1.5 L of ethyl acetate was added, and the upper organic phase was separated and washed with 10% NaCl solution three times. The organic phase was dried over anhydrous sodium sulfate, concentrated, and chromatographed on a silica gel column (n-heptane / ethyl acetate 2 / 1–0 / 1) to obtain 67.6 g of the product.

[0116] Compound 20, colorless oil, two-step yield 51%. 1 H NMR (500MHz, CDCl3) δ7.60-7.67(m,4H),7.42-7.48(m,6H),4.16(t,J=5Hz,2 H), 3.64 (t, J = 5Hz, 2H), 3.38 (d, J = 5Hz, 4H), 3.26-3.31 (m, 4H), 0.99 (s, 9H).

[0117] S3, synthesis of compound 21;

[0118] Add 600 mL of THF to compound 20 (67.6 g, 1.0 eq.) and stir to dissolve; add NaH (33.4 g, 9.0 eq.) under nitrogen protection, and slowly drop propargyl bromide (6.0 eq.) under nitrogen protection. After the addition is completed, heat to 25±5°C and react for 60 h.

[0119] The reaction mixture was cooled to 0-5°C, quenched with NH4Cl aqueous solution, extracted with ethyl acetate, and the organic phase was washed three times with 10% NaCl solution, dried over anhydrous sodium sulfate, concentrated, and chromatographed on a silica gel column (n-heptane / ethyl acetate 50 / 1) to obtain 42.4 g of the product.

[0120] Compound 21, colorless oil, yield 51%. 1 H NMR (500MHz, CDCl3) δ7.66-7.67(m,4H),7.36-7.43(m,6H),4.11(d,J=5Hz,6H),3.65(t,J=5Hz,2H),3 .52(s,6H),3.35-3.38(m,4H),3.38(t,J=5Hz,3H),1.49-1.61(m,4H),1.31-1.37(m,4H),1.05(s,9H).

[0121] S4. Synthesis of compound 22:

[0122] Compound 21 (41.7 g, 1.0 eq.) was dissolved in 400 mL F025, and TBAF (5.0 eq.) was added at 0-5°C, and the temperature was raised to 20°C for reaction for 16 h. The mixture was extracted with ethyl acetate, and the organic phase was washed three times with 10% NaCl solution, dried over anhydrous sodium sulfate, concentrated, and chromatographed on a silica gel column (n-heptane / ethyl acetate 50 / 1-1 / 1) to obtain 23.4 g of the product.

[0123] Compound 22, light yellow oil, yield 94%. 1H NMR(500MHz, CDCl3)δ4.12(d,J=5Hz,6H),3.64(q,J=5Hz,2H),3.52(s,6H),3 .38-3.41(m,4H),2.41(t,J=5Hz,3H),1.53-1.60(m,4H),1.36-1.38(m,4H).

[0124] S5. Synthesis of compound 23:

[0125] Compound 22 (15.6 g, 1.0 eq.) was dissolved in 150 mL DCM to obtain 66 ppm of KF, and triethylamine (2 eq.) and diisopropylamino cyanoethoxyphosphonium chloride (1.5 eq.) were added at 0-5°C, and the temperature was raised to 20°C for 4 h. The reaction of the raw material was monitored by TLC.

[0126] The reaction solution was washed twice with NaHCO3 aqueous solution at 0-5°C, and the organic phase was washed twice with 10% NaCl solution. The organic phase was dried over anhydrous sodium sulfate, concentrated, and chromatographed on a silica gel column (n-heptane / ethyl acetate 10 / 1) to obtain 10.7 g of the product.

[0127] Compound 23, light yellow oil, yield 44%. 1 H NMR (500MHz, CDCl3) δ4.11 (d, J = 5Hz, 6H), 3.79-3.85 (m, 2H), 3.56-3.68 (m, 4H), 3.51 (s, 6H), 3.37-3.39 (m, 4 H), 2.64 (t, J = 5Hz, 2H), 2.63 (t, J = 5Hz, 3H), 1.51-1.64 (m, 4H), 1.36-1.37 (m, 4H), 3.64 (dd, J = 5Hz, 5Hz, 12H). 31 PNMR (202MHz, CDCl3) δ147.4ppm.

[0128] Application Synthesis Example 1

[0129] The delivery compound (Compound 39) was synthesized according to the following synthetic route:

[0130]

[0131]

[0132] S1. Synthesis of compound 36:

[0133] Compound 17 (0.4 g, 1.0 eq.) was dissolved in dichloromethane (10 V, 4 ml) at 20-25 °C, cooled to 0-10 °C, and powdered molecular sieves (0.3 g) were directly added. After stirring for 20 minutes, compound 31 (0.264 g, 1.0 eq) was added, followed by tetrazole (0.02 g, 1.5 eq). After addition, the mixture was reacted at 27±2 °C for 1 h. The solution was directly used in the next step.

[0134] S2. Synthesis of compound 37:

[0135] To the reaction system of compound 36 in the previous step, tert-butyl hydroperoxide solution (0.0345 g, 2.0 eq) was added and the mixture was reacted at 27±2°C for 1 h.

[0136] Post-treatment: The reaction solution was cooled to 0-10°C, quenched by adding 10 ml of 10% sodium thiosulfate aqueous solution, stirred for 10 minutes, extracted with diatomaceous earth (3 g), and the filtrate was separated. The organic phase was extracted once with 10 ml of 5% sodium bicarbonate aqueous solution, and then extracted once with 10 ml of 10% sodium chloride aqueous solution. The organic phase was dried over 3 g of sodium sulfate and concentrated under reduced pressure at 30±2°C to give 0.4 g of crude product, which was used directly in the next step.

[0137] S3. Synthesis of compound 38:

[0138] Add 45 ml of a mixed solution of ammonia and ethanol = 2 / 1 (V / V) to the crude product of compound 37 in the previous step, and react at 27±2℃ for 15h.

[0139] Post-treatment: The reaction solution was directly concentrated to dryness at 30±2°C to obtain 0.3 g of a crude product, which was directly used in the next step.

[0140] S4. Synthesis of compound 39:

[0141] Compound 38 (0.3 g, 1 eq.) was dissolved in a mixed solution of 10 ml methanol and 3 ml dichloromethane, and dodecanethiol (0.27 g, 7 eq) and dichloroacetic acid (0.17 g, 7 eq) were added at 0-5°C and reacted for 15 h.

[0142] Post-treatment quenching: add 3 ml of 5% sodium bicarbonate aqueous solution to the reaction solution for quenching, stir for 10 minutes, and concentrate the reaction system to dryness under reduced pressure at 30±2° C. The crude product was prepared by reverse phase to obtain 0.11 g of product.

[0143] Compound 6 is a purple oil with a yield of 36.6%. Purity spectrum: 1H NMR (500MHz, DMSO) δ8.36(dd,J=30.6,17.1Hz,1H),8.00–7.87(m,J=12.8,7.6Hz,2H),7.73(d,J=9.0Hz,2H),7.62(d,J=7.0Hz, 1H),7.49–7.38(m,2H),7.33–7.24(m,J=7.1Hz,1H),6.68(d,J=13.5Hz,1H),6.60(d,J=13.5Hz,1H),4.21(d,J=8.3Hz,4H),4.0 9–3.76(m,3H),3.74–3.60(m,7H),3.57–3.40(m,14H),3.38–3.24(m,6H),3.20(s,6H),3.00(d,J=5.9Hz,4H),2.34–2.20(m,6H ),2.01(s,1H),1.95–1.82(m,3H),1.77(d,J=17.5Hz,59H),1.70(d,J=3.5Hz,7H),1.45–1.30(m,8H),1.21(d,J=20.6Hz,10H). 31 P NMR (202 MHz, DMSO) δ 0.03.

[0144] Application Example 2

[0145] The delivery compound (Compound 45) was synthesized according to the following synthetic route:

[0146]

[0147]

[0148] S1. Synthesis of compound 41:

[0149] Compound 23 (0.2 g, 1.0 eq.) was dissolved in dichloromethane (10 V, 2 ml) at 20-25 °C, cooled to 0-10 °C, and powdered molecular sieves (0.4 g) were directly added. After stirring for 20 minutes, compound 40 (0.39 g, 1.5 eq) was added, and then tetrazole (0.0509 g, 2.0 eq) was added. After addition, the mixture was reacted at 27±2 °C for 1 h. The solution was directly used in the next step.

[0150] S2. Synthesis of compound 42:

[0151] To the reaction system of compound 41 in the previous step, tert-butyl hydroperoxide solution (0.66 g, 2.0 eq) was added and the mixture was reacted at 27±2°C for 1 h.

[0152] Post-treatment: The reaction solution was cooled to 0-10°C, quenched by adding 10 ml of 10% sodium thiosulfate aqueous solution, stirred for 10 minutes, extracted with diatomaceous earth (3 g), and the filtrate was separated. The organic phase was extracted once with 10 ml of 5% sodium bicarbonate aqueous solution, and then extracted once with 10 ml of 10% sodium chloride aqueous solution. The organic phase was dried over 1 g of sodium sulfate and concentrated under reduced pressure at 30±2°C to give 0.35 g of a crude product, which was used directly in the next step.

[0153] S3. Synthesis of compound 43:

[0154] The crude compound 42 (0.35 g, 1 eq.) from the previous step was dissolved in methanol (4 mL). After dissolution, compound 5 (0.997 g, 3.625 eq.) was added. THPTA (0.06 g, 0.375 eq.) and copper sulfate (0.0069 g, 0.076 eq.) were added to 0.5 ml of water in sequence. After complete dissolution, they were added to the reaction system. Then sodium ascorbate (0.0111 g, 0.151 eq.) was added to 0.5 ml of water. After addition, the mixture was stirred for 10 minutes and the stirring timer was started for 15 hours.

[0155] Post-treatment: The reaction solution was cooled to 0-5°C, extracted once with 10 ml of 5% sodium bicarbonate aqueous solution, and then extracted once with 10 ml of 10% sodium chloride aqueous solution, the lower organic phase was separated, and the organic phase was concentrated to dryness at 30±2°C to obtain 0.75 g of crude product, which was directly used in the next step.

[0156] S4. Synthesis of compound 44:

[0157] Compound 43 (0.75 g, 1 eq.) was dissolved in 45 ml of a mixed solution of ammonia and ethanol = 2:1 and reacted at 27±2°C for 30 h.

[0158] Post-treatment quenching: add 3 ml of 5% sodium bicarbonate aqueous solution to the reaction solution for quenching, stir for 10 minutes, and concentrate the reaction system under reduced pressure at 30±2°C to dryness. Obtain 0.7 g of crude product, which is prepared by reverse phase, and 250 ml of reverse phase preparation solution is concentrated under reduced pressure at 30±2°C to dryness to obtain 0.5 g of product, which is directly used in the next step.

[0159] S5. Synthesis of compound 45:

[0160] Compound 44 (0.5 g, 1 eq.) was dissolved in a mixed solution of 10 ml methanol and 3 ml dichloromethane, and dodecanethiol (0.44 g, 5 eq) and dichloroacetic acid (0.28 g, 6 eq) were added at 0-5°C and reacted for 15 h.

[0161] Post-treatment quenching: add 3 ml of 5% sodium bicarbonate aqueous solution to the reaction solution for quenching, stir for 10 minutes, and concentrate the reaction system under reduced pressure at 30±2°C to dryness. Obtain 0.3 g of crude product, which is prepared by reverse phase, and 250 ml of reverse phase preparation solution is concentrated under reduced pressure at 30±2°C to dryness to obtain 0.15 g of product.

[0162] Compound 45 is a purple oil with a yield of 30%. Purity spectrum:

[0163] 1 H NMR (500MHz, DMSO) δ8.01(s,2H),7.73(dd,J=16.1,9.0Hz,2H),7.62(dd,J=7.4,1.8Hz,1H),7.44(ddd,J=20.9,8.1,2.8Hz,2H ),7.28(dd,J=12.2,7.0Hz,1H),7.13–6.97(m,1H),6.79–6.60(m,2H),4.50(t,J=5.2Hz,7H),4.43(s,6H),4.27(dd,J=8.4,1.6 Hz,3H),4.20(s,3H),3.80(t,J=5.2Hz,5H),3.78–3.60(m,12H),3.57–3.38(m,35H),3.32–3.19(m,6H),3.16(s,7H),1.84–1.7 5(m,46H),1.69(d,J=3.1Hz,5H),1.51(s,1H),1.46(s,2H),1.37(dt,J=13.6,6.8Hz,1H),1.21(d,J=23.6Hz,5H),0.86(s,1H). 31 P NMR (202 MHz, DMSO) δ 0.03.

[0164] Application Comparative Example 1

[0165] The delivery compound (Compound 35) was synthesized according to the following synthetic route:

[0166]

[0167] S1. Synthesis of compound 32:

[0168] Compound L96 (1 g, 1.0 eq.) was dissolved in dichloromethane (10 V, 10 ml) at 20-25 °C, cooled to 0-10 °C, and powdered molecular sieves (0.6 g) were directly added. After stirring for 20 minutes, compound 31 (0.27 g, 1.0 eq) was added, and then tetrazole (0.04 g, 1.5 eq) was added. After addition, the mixture was reacted at 27±2 °C for 1 h. The solution was directly used in the next step.

[0169] S2. Synthesis of compound 33:

[0170] To the reaction system of compound 32 in the previous step, tert-butyl hydroperoxide solution (0.069 g, 2.0 eq) was added and the mixture was reacted at 27±2°C for 1 h.

[0171] Post-treatment: The reaction solution was cooled to 0-10°C, quenched by adding 10 ml of 10% ammonium thiosulfate aqueous solution, stirred for 10 minutes for extraction, filtered with diatomaceous earth (3 g), the filtrate was separated, the organic phase was extracted once with 10 ml of 5% sodium bicarbonate aqueous solution, and then extracted once with 10 ml of 10% sodium chloride aqueous solution. The organic phase was dried over 1 g of sodium sulfate and concentrated under reduced pressure at 30 ± 2°C to give 1 g of crude product, which was used directly in the next step.

[0172] S3. Synthesis of compound 34:

[0173] Add 45 ml of a mixed solution of ammonia and ethanol = 2 / 1 (V / V) to the crude product of compound 33 in the previous step, and react at 27±2℃ for 15h.

[0174] Post-treatment: The reaction solution was directly concentrated to dryness at 30±2°C to obtain 0.8 g of a crude product, which was directly used in the next step.

[0175] S4. Synthesis of compound 35:

[0176] Compound 34 (0.8 g, 1 eq.) was dissolved in a mixed solution of 10 ml methanol and 3 mL dichloromethane, and dodecanethiol (0.54 g, 7 eq) and dichloroacetic acid (0.35 g, 7 eq) were added at 0-5°C and reacted for 15 h.

[0177] Post-treatment quenching: add 3 ml of 5% sodium bicarbonate aqueous solution to the reaction solution for quenching, stir for 10 minutes, and concentrate the reaction system to dryness under reduced pressure at 30±2° C. The crude product is prepared by reverse phase to obtain 0.2 g of product.

[0178] Compound 35 is a purple oil with a yield of 40%. Purity spectrum:

[0179] 1H NMR (500MHz, DMSO) δ8.34(t,J=13.4Hz,1H),7.94(d,J=5.3Hz,2H),7.86(t,J=5.3Hz,2H),7.77(d,J=9.1Hz,2H),7.62(d,J=7.2Hz,1H), 7.50–7.38(m,J=8.1Hz,3H),7.28(dd,J=12.0,6.9Hz,1H),7.02(s,1H),6.66(dd,J=38.4,13.4Hz,2H),4.67(s,1H),4.21(d,J=8.4Hz,5 H),3.95(s,1H),3.80–3.63(m,10H),3.59–3.37(m,23H),3.38–3.25(m,6H),3.10–2.92(m,11H),2.28(t,J=6.3Hz,5H),2.14(dd,J=9.8 ,6.7Hz,1H),2.04(t,J=7.3Hz,7H),2.01–1.88(m,4H),1.78(d,J=8.3Hz,44H),1.70(d,J=4.1Hz,9H),1.56–1.34(m,21H),1.19(s,12H). 31 P NMR (202 MHz, DMSO) δ -1.87.

[0180] Experimental Example 1

[0181] Using flow cytometry, monkey primary hepatocytes were tested for their internalization effects on the above three delivered compounds (Compound 35, Compound 39 and Compound 45).

[0182] The experimental conditions are as follows:

[0183]

[0184] Experimental methods:

[0185] 1. Cell culture plate coating (adherent hepatic parenchymal cells)

[0186] The surface of the 96-well plate was pretreated with 100 μL of collagen coating solution (HCM-R) to enhance the adhesion of hepatic parenchymal cells to the surface of the culture plate, and the coating was incubated in a CO2 incubator at 37°C for 4 hours.

[0187] 2. Cell Recovery

[0188] Remove the cell cryovial from the liquid nitrogen tank and immediately place it in a 37°C water bath. Gently shake the cryovial for about 1 min 45 s to melt until a small amount of ice crystals (soybean size) remain in the tube. Disinfect the surface of the cryovial with 75% alcohol and quickly transfer it to a biosafety cabinet. Quickly pour the liquid in the cryovial into the preheated 40 mL recovery medium (HTS-R). Pipette 1 mL of recovery medium to rinse the inner wall of the cryovial (2 to 3 times), and transfer the rinsed medium to the centrifuge tube in step 3). Tighten the centrifuge tube cap and slowly turn the centrifuge tube upside down twice to mix the cell suspension. Centrifuge at room temperature. Please select the centrifugation speed and time according to the cell species (monkey hepatocytes 180g, 1 min), set the speed up to 5, the speed down to 1, and turn off the brake mode. Use a pipette or Pasteur pipette to carefully remove the supernatant (do not pour the supernatant directly to avoid cell loss). Please keep about 0.5 mL of supernatant. Do not let the pipette or pipette touch the cell pellet. Please select the appropriate culture medium for resuspending and fixing the volume according to the specific type of hepatocytes. For adherent hepatocytes, use the plating medium (HPM-R). Add 2mL of the corresponding culture medium, flick the bottom of the centrifuge tube to resuspend the cells and fix the volume to 3mL. Do not shake violently or blow repeatedly during this process.

[0189] 3. Cell Plating

[0190] Dilute the cell suspension to 4.0×10 5 / mL inoculation concentration. Gently shake the cell suspension, take 100μL of cell suspension and inoculate it into the coated cell culture plate (discard the coating solution), and ensure that the number of cells in the duplicate wells is as similar as possible.

[0191] 4. Preparation of labeled drugs and addition to cell plates

[0192] Dilute the labeled drug to 5 times the final concentration of the corresponding action with maintenance medium. Add the diluted labeled drug to the corresponding cell wells at 25 μL / well (starting at 100uM, 5-fold dilution, 9 concentrations), and fill the blank control with maintenance medium to 125 μL. Place the 96-well plate in the incubator for incubation, and set the incubation time to 24h.

[0193] 5. Sample collection and testing

[0194] Remove the cell plate from the incubator, wash the cells once with PBS, add preheated trypsin for digestion, then terminate the digestion with maintenance medium, centrifuge at 180g for 1 minute, and discard the supernatant. Add 100μL / well culture medium to resuspend the cells and complete the sample preparation for the machine. Collect samples using Beckman cytoflex flow cytometer. Determine the voltage parameters based on the control tube. After completing the sample collection, use Flowjo software to analyze the MFI value.

[0195] Results Figure 1 , where HG-A represents the result for compound 35; HG-B represents the result for compound 39; and HG-C represents the result for compound 45.

[0196] Compared with the most commonly used L96 GalNAc, the delivery compounds provided in the application examples of the present invention have achieved ideal cellular uptake effects, indicating that the N-acetylgalactosamine-modified pentaerythritol derivatives provided in the embodiments of the present invention can achieve good use effects in practical applications, and compared with the GalNAc molecules currently on the market, it provides a new structure and has the advantages of simple synthesis and high efficiency.

[0197] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping, characterized in that: It is selected from the compounds represented by the following structural formula: Wherein, X is H or a hydroxyl protecting group, Y is an amino protecting group, A, B and C are independently selected from at least one of hydrogen, carbon, oxygen, sulfur and phosphorus to form a linking group, and D is a linking group for solid phase synthesis of oligonucleotides.

2. The N-acetylgalactosamine-modified pentaerythrityl tetraether derivative for oligonucleotide end-capping according to claim 1, characterized in that: It is selected from any one of the compounds represented by the following structural formulas: Wherein, when LR is used as a group, LR can be selected from H or phosphoramidite; When L and R are two groups, L is selected from an ester group or an amide bond; R is selected from a group connected to L or a solid support; Z is selected from a hydroxy protecting group or H; In the structural formula Ia, the dotted line represents a ring structure, L and Any position on the ring; The dotted line in structural formula Ia represents a chain structure. lie in Any position on the chain; R1 is selected from a phosphoramidite group or a solid support; Preferably, it is selected from the compounds shown in the following structural formula: Z is selected from a hydroxyl protecting group or H; L is selected from an ester group or an amide bond; and R is selected from a group connected to L or a solid phase carrier.

3. The N-acetylgalactosamine-modified pentaerythrityl tetraether derivative for oligonucleotide end-capping according to claim 1 or 2, characterized in that: C is an amide group or a triazole; Preferably, C is n is any value from 1 to 5.

4. The N-acetylgalactosamine-modified pentaerythrityl tetraether derivative for oligonucleotide end-capping according to claim 3, characterized in that: X and Y are each independently selected from an acyl group, preferably a C2-C10 acyl group, more preferably an acetyl group, a benzoyl group or an isopropanoyl group.

5. The N-acetylgalactosamine-modified pentaerythrityl tetraether derivative for oligonucleotide end-capping according to claim 3, characterized in that: A is an amide group or an alkyl group; more preferably a C1-C10 amide group and a C1-C15 unsubstituted alkyl group; further preferably a C1-C5 amide group and a C1-C10 unsubstituted alkyl group; more preferably any one of formamide, acetamide, methyl, ethyl and propyl.

6. The N-acetylgalactosamine-modified pentaerythrityl tetraether derivative for oligonucleotide end-capping according to claim 3, characterized in that: B is an alkyl group or a polyether group; preferably a C1-C20 unsubstituted alkyl group or a polyethylene glycol group of different lengths; more preferably a C1-C10 unsubstituted alkyl group or -(CH2CH2O) m , m is 2-15; most preferably C1-C5 unsubstituted alkyl.

7. The N-acetylgalactosamine-modified pentaerythrityl tetraether derivative for oligonucleotide end-capping according to claim 3, characterized in that: It is selected from any one of the compounds represented by the following structural formulas:

8. A method for preparing the N-acetylgalactosamine modified pentaerythritol derivative for oligonucleotide end-capping according to claim 3, characterized in that: include: After constructing three ether bonds by Michael addition reaction using terminal alkynes or terminal olefins containing protective groups; The above-mentioned protecting group is then modified to attach a group containing GalNAc; Alternatively, a halogen-containing compound is used to carry out an alkylation reaction to construct three ether bonds, and then the protective group above is modified to connect a GalNAc-containing group.

9. A delivery compound capable of achieving drug delivery, characterized in that: It comprises a bonding compound and the N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping according to claim 1, wherein the bonding compound and the N-acetylgalactosamine-modified pentaerythritol derivative for oligonucleotide end-capping are connected through their D groups; Preferably, the bonding compound is selected from a nucleotide chain or a fluorescent compound.

10. A nucleotide drug, characterized in that: It comprises the delivery compound capable of achieving drug delivery as claimed in claim 9.

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