Chemical synthesis of cytidine-5'-monophospho-N-glycyl-sialic acid

Abstract

Aspects of the present disclosure provide a method for chemically synthesizing cytidine-5'-monophospho-N-glycyl-sialic acid (GSC).

Description

[Technical field]

[0001] <Related Applications> This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 265,744, filed December 20, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] The present disclosure relates to the field of chemical synthesis of cytidine-5'-monophospho-N-glycyl-sialic acid. Summary of the Invention

[0003] An embodiment of the present disclosure provides a method for the synthesis of cytidine-5'-monophospho-N-glycyl-sialic acid (GSC).

[0004] In some embodiments, the method of the present invention comprises two or more steps, and a first step of the two or more steps comprises benzylation of N-acetylneuraminic acid. In some embodiments, the first step comprises synthesis of benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate. In some embodiments, the two or more steps include synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof. In some embodiments, the two or more steps include a step of synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate, a step of synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate, and a step of synthesizing benzyl (2R,4S,5R)-5-acetamido-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate. a step of synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-[acetyl(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; a step of synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-(tert-butoxycarbonylamino)-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate;A step of synthesizing 6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium, a step of synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate, and a step of synthesizing benzyl (2S,4S,5R)- a step of synthesizing 4-acetoxy-2-hydroxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; and a step of synthesizing benzyl(2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphanyloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate. and synthesizing benzyl(2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate. and synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof.

[0005] Provided herein is a method for synthesizing cytidine-5'-monophospho-N-glycyl-sialic acid (GSC), the method comprising the steps of synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate, synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate, and reacting benzyl (2R, A process for synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-[acetyl(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; a process for synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; a step of synthesizing [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium; and a step of synthesizing benzyl(2R,4S,5R)-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate. a step of synthesizing benzyl (2S,4S,5R)-4-acetoxy-2-hydroxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; a step of synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphanyloxy-6-[(1S,A process for synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; a process for synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; The method includes the steps of synthesizing N-acetylneuraminic acid, (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof, or any combination of the steps described above. In some embodiments, the starting material is N-acetylneuraminic acid.

[0006] Provided herein is a method for synthesizing cytidine-5'-monophospho-N-glycyl-sialic acid (GSC) from N-acetylneuraminic acid, the method comprising one or more of the following reactions: benzylation, acetylation, introduction of a thiophenol group, Boc protection, deacetylation, Boc deprotection, introduction of a TFA-Gly group, removal of the thiophenol group, introduction of a phosphite group, debenzylation, triacetyl-cytidine coupling, acetyl and trifluoroacetamide deprotection.

[0007] Provided herein is a process for producing cytidine-5'-monophospho-N-glycyl-sialic acid (GSC), comprising: a. Benzylation of Neu5AC to obtain intermediate 1; [ka] b. acetylation of intermediate 1 to obtain intermediate 2; [ka] c. introducing a thiophenol group into intermediate 2 to obtain intermediate 3; [ka] d. Boc protection of intermediate 3 to give intermediate 4; [ka] e. deacetylation of intermediate 4 to obtain intermediate 5; [ka] f. acetylation of intermediate 5 to obtain intermediate 6; [ka] g. Boc deprotection of intermediate 6 to give intermediate 7; [ka] h. introducing a TFA-Gly group into intermediate 7 to obtain intermediate 8; [ka] i. removal of the thiophenol group of intermediate 8 to obtain intermediate 9; [ka] j. introducing a phosphite group into intermediate 9 to obtain intermediate 10; [ka] k. oxidation of intermediate 10 to obtain intermediate 11; [ka] l. debenzylation of intermediate 11 to obtain intermediate 12; [ka] m. triacetyl-cytidine coupling of intermediate 12 to obtain intermediate 13; [ka] n. Acetyl and trifluoroacetamide deprotection of intermediate 13; [ka] A method is provided that includes: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the compositions and methods of the present disclosure.

[0009] Disclosed herein is a process for synthesizing cytidine-5'-monophospho-N-glycyl-sialic acid. In some embodiments, the synthesis comprises several steps.

[0010] In some embodiments, the process has 2 or more steps. In some embodiments, the process has 3 or more steps. In some embodiments, the process has 4 or more steps. In some embodiments, the process has 5 or more steps. In some embodiments, the process has 6 or more steps. In some embodiments, the process has 7 or more steps. In some embodiments, the process has 8 or more steps. In some embodiments, the process has 9 or more steps. In some embodiments, the process has 10 or more steps. In some embodiments, the process has 11 or more steps. In some embodiments, the process has 12 or more steps. In some embodiments, the process has 13 or more steps. In some embodiments, the process has 14 or more steps. In some embodiments, the process has between 2 and 14 steps. In some embodiments, the process of the present invention is a 14 step process.

[0011] In some embodiments, the process of the present invention comprises one or more of benzylation, acetylation, thiophenol group introduction, Boc protection, deacetylation, Boc deprotection, TFA-Gly group introduction, thiophenol group removal, phosphite group introduction, debenzylation, triacetyl-cytidine coupling, acetyl and trifluoroacetamide deprotection reactions.

[0012] In some embodiments, the process of the present invention is a 14-step process. In some embodiments, the 14-step process comprises: Step 1: Benzylation of N-acetylneuraminic acid (NeuAc) Step 2: Acetylation Step 3: Thiophenol group introduction Step 4: Boc protection Step 5: Deacetylation Step 6: Acetylation Step 7: Boc deprotection Step 8: TFA-Gly group introduction Step 9: Removal of thiophenol group Step 10: Phosphite group introduction Step 11: Oxidation Step 12: Debenzylation Step 13: Triacetyl-cytidine coupling Step 14: Acetyl and trifluoroacetamide deprotection Includes.

[0013] In some embodiments, one or more steps may be removed and / or replaced. For example, in some embodiments, the process of the invention may have 13 steps, 12 steps, 11 steps, 10 steps, 9 steps, or less than 9 steps. In some embodiments, one or more steps may be replaced. In some embodiments, other reagents that are compatible with the overall chemistry and known in the art may be substituted.

[0014] In some embodiments, the process of the invention involves synthesizing one or more of the compounds in Tables 1-1-3.

[0015] [Table 1-1]

[0016] [Table 1-2]

[0017] [Table 1-3]

[0018] In some embodiments, the process of the invention involves the synthesis of an intermediate in Table 1.

[0019] In some embodiments, the starting material comprises or is N-acetylneuraminic acid. In some embodiments, the starting material comprises or is N-acetylneuraminic acid, and the method of the invention comprises (2R,4S,5R)-5-[(2-aminoacetyl)amino]-2-[[(2R,3S,4R,5R)-5-(4-amino-2-oxo-pyrimidin-1-yl)-3,4-dihydroxy-tetrahydrofuran-2-yl]methoxy-oxido-phosphoryl]oxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyrimidin-1-yl]oxy]. The method includes a step of synthesizing disodium (2R,4S,5R)-5-[(2-aminoacetyl)amino]-2-[[(2R,3S,4R,5R)-5-(4-amino-2-oxo-pyrimidin-1-yl)-3,4-dihydroxy-tetrahydrofuran-2-yl]methoxy-oxido-phosphoryl]oxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate or a salt thereof.

[0020] In some embodiments, the methods of the present invention include the step of preparing a compound comprising (2R,4S,5R)-5-[(2-aminoacetyl)amino]-2-[[(2R,3S,4R,5R)-5-(4-amino-2-oxo-pyrimidin-1-yl)-3,4-dihydroxy-tetrahydrofuran-2-yl]methoxy-oxide-phosphoryl]oxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate or its derivative. The salt may be prepared, for example, by synthesis of disodium; (2R,4S,5R)-5-[(2-aminoacetyl)amino]-2-[[(2R,3S,4R,5R)-5-(4-amino-2-oxo-pyrimidin-1-yl)-3,4-dihydroxy-tetrahydrofuran-2-yl]methoxy-oxide-phosphoryl]oxy-4-hydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate.

[0021] In some embodiments, the methods of the invention include synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate.

[0022] In some embodiments, the methods of the invention include synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate.

[0023] In some embodiments, the methods of the invention include synthesizing benzyl (2R,4S,5R)-5-acetamido-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate.

[0024] In some embodiments, the method of the present invention includes synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-[acetyl(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate.

[0025] In some embodiments, the method of the present invention includes synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-(tert-butoxycarbonylamino)-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate.

[0026] In some embodiments, the method of the present invention comprises synthesizing [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium. In some embodiments, the method of the present invention comprises synthesizing [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium salt. In some embodiments, the method of the present invention comprises synthesizing [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium chloride.

[0027] In some embodiments, the methods of the invention include synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate.

[0028] In some embodiments, the methods of the invention include synthesizing benzyl (2S,4S,5R)-4-acetoxy-2-hydroxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate.

[0029] In some embodiments, the methods of the invention include synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphanyloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate.

[0030] In some embodiments, the methods of the invention include synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate.

[0031] In some embodiments, the method of the invention includes synthesizing [(2R,4S,5R)-4-acetoxy-2-carboxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-yl]hydrogenphosphate;triethylammonium.

[0032] In some embodiments, the method of the present invention includes synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof.

[0033] In some embodiments, the method of the present invention includes one or more steps, the one or more steps being a step of synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate, a step of synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate, and a step of synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate. A step of synthesizing amide-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate, a step of synthesizing benzyl(2R,4S,5R)-4-acetoxy-5-[acetyl(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate, and a step of synthesizing benzyl(2R,4S,5R)-4-acetoxy-5-(tert-butoxycarbonylamino) -2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium; and benzyl(2R,4S,5R)-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[ A process for synthesizing 2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate, a process for synthesizing benzyl (2S,4S,5R)-4-acetoxy-2-hydroxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate, and a process for synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphanyloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl(2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing [(2R,4S,5R)-4-acetoxy-2-carboxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[( The method includes the steps of synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof.

[0034] In some embodiments, the process of the invention is a 14-step process as described in Example 1.

[0035] For convenience, some terms used in the specification, examples, and appended claims are collected below: Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0036] As used herein, the following terms and phrases are intended to have the following meanings:

[0037] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "an element" means one element or one or more than one element.

[0038] As used herein, the terms "comprising" or "comprising" are used to refer to compositions, methods, and their respective components that are present in a particular embodiment but may include unspecified elements.

[0039] As used herein, the term "consisting essentially of" refers to elements required for a given embodiment. The term permits the presence of additional elements that do not materially affect the basic and novel or functional characteristics of that embodiment of the present disclosure.

[0040] The term "consisting of" refers to compositions, methods, and individual components described herein, and excludes any element not recited in the description of the embodiment.

[0041] As used herein, the term "comprising" includes "consisting of" and "consisting essentially of."

[0042] Whenever reference is made herein to "as above" or "above" or "above," it refers to any of the disclosures made herein in any of the preceding pages.

[0043] Whenever the description includes "as described herein," "as described herein," "as provided herein," "as described in the text," or "as described herein," it refers to either the disclosure made in the preceding or subsequent pages of the specification.

[0044] As used herein, the term "about" refers to an acceptable variation of within 20%, 10%, or 5% of the stated value. In some embodiments, "about" can refer to a variation of + / - 1%, 2%, 3%, 4%, 5%, 10%, or 20%. EXAMPLES

[0045] Example 1: 14-step process for synthesizing GSC <Step 1: Benzylation> [Table 2]

[0046] <Preparation> N-Acetylneuraminic acid (400 g, 1.288 mol, 1 eq.) was suspended in dimethylformamide (2 L). Cesium carbonate (251.4 g, 0.764 mol, 0.59 eq.) was added in three portions of 83.8 g each. The resulting suspension was stirred at room temperature for 1 h. Benzyl bromide (239 mL, 1.96 mol, 1.52 eq.) was added dropwise over 1.5 h. The reaction mixture was stirred at room temperature for 16 h.

[0047] The reaction mixture was filtered through Celite and the solid was washed twice with dimethylformamide (2×300 mL). The filtrates were combined, evaporated to dryness and coevaporated once with toluene (1×800 mL) to give an off-white gum. Isopropanol (5.2 L) was added to the residue, which was then heated at 80° C. for 15 min. The suspension was then slowly cooled to room temperature and stirred overnight. The precipitated solid was filtered, washed twice with isopropanol and then dried under reduced pressure at 40° C. to give 463.2 g of 1 as a white solid.

[0048] <Step 2: Acetylation> [Table 3]

[0049] <Preparation> The above 1 (814.8 g, 1.644 mol, 1 eq.) was suspended in tetrahydrofuran (4 L) and pyridine (1320 mL, 16.4 mol, 10 eq.). 4-Dimethylaminopyridine (32.45 g, 0.263 mol, 0.16 eq.) was added at room temperature. Acetic anhydride (1.3 L, 13.2 mol, 8 eq.) was added dropwise at 0° C. over 2 hours. The reaction mixture was stirred at room temperature for 16 hours.

[0050] The reaction mixture was concentrated to 50 mBar at 50° C. and ethyl acetate (10 L) was added. The resulting organic phase was washed successively with 2×10 L of 1N aqueous HCl, 2×10 L of saturated aqueous sodium bicarbonate, and 3 L of brine. The organic layer was dried over sodium sulfate, filtered, and evaporated to dryness to give 990 g of 2 as a white foam.

[0051] <Step 3: Introduction of thiophenol group> [Table 4]

[0052] <Preparation> 2 (920 g, 1.479 mol, 1 eq.) was dissolved in acetonitrile (2300 mL). Thiophenol (234 mL, 2.22 mol, 1.5 eq.) was added at room temperature. Boron trifluoride diethyl etherate (365 mL, 2.957 mol, 2 eq.) was added dropwise over 11 min at 0° C. The reaction mixture was stirred at 0° C. for 5 min and then at 30° C. for 22 h.

[0053] Saturated aqueous sodium carbonate (4200 mL) was added to the reaction mixture over 20 min at 0° C. Benzyl bromide (180 mL, 1.479 mol, 1 eq.) was added to quench excess thiophenol. The resulting suspension was stirred at room temperature for 22 h.

[0054] The reaction mixture was diluted with water (4 L) and ethyl acetate (4 L). The resulting organic phase was washed with brine (2 L) and evaporated under reduced pressure to give an orange oil.

[0055] The oil was dissolved in acetonitrile (4 L) and water (1 L). The resulting solution was washed five times with heptane (6×5 L), concentrated under reduced pressure, and coevaporated twice with toluene (2×4 L) and then with THF (2 L) to give 3 as a white foam.

[0056] <Step 4: Boc protection> [Table 5]

[0057] <Preparation> The above 3 (1020 g, 1.263 mol, 1.0 eq.) was dissolved in THF (1.5 L) and Na2SO4 (200 g) was added. The suspension was filtered and the solid was washed with THF (2 x 250 ml). To the obtained filtrate was added a solution of di-tert-butyl dicarbonate (557 g, 2.526 mol, 2 eq.) in tetrahydrofuran (500 mL) at room temperature, followed by 4-dimethylaminopyridine (31.2 g, 0.253 mol, 0.2 eq.). The obtained reaction mixture was stirred at 55 °C for 22 h. The reaction mixture was used directly in the next step.

[0058] <Step 5: Deacetylation> [Table 6] <Preparation>

[0059] The reaction mixture from the previous step was cooled to 0° C. and methanol (2.5 L) was added followed by hydrazine monohydrate (313 mL, 6.32 mol, 5 eq.) The resulting reaction mixture was stirred at 0° C. for 10 min and then at room temperature for 3 h.

[0060] The reaction mixture was diluted with ethyl acetate (7.0 L) and 1N aqueous HCl (5 L). The organic phase was washed with 1N aqueous HCl (2.5 L) and then with brine (2.5 L). The organic phase was evaporated under reduced pressure to give 926 g of a dark orange oil. This crude product was used directly in the next step.

[0061] In some embodiments, hydrazine monohydrate is replaced by dimethylaminopropylamine.

[0062] <Step 6: Acetylation> [Table 7]

[0063] <Preparation> The crude product from the previous step (926 g, 1.263 mol) was dissolved in tetrahydrofuran (2200 mL) and pyridine (514 mL, 6.316 mol, 5 eq.). Acetic anhydride (482 mL, 5.053 mol, 4 eq.) was added dropwise over 8 min at 0° C. 4-Dimethylaminopyridine (15.59 g, 0.126 mol, 0.1 eq.) was added at 0° C. The resulting reaction mixture was stirred at room temperature for 15 h.

[0064] The reaction mixture was diluted with ethyl acetate (7 L). The resulting organic phase was washed twice with 1N aqueous HCl (2×7 L), twice with saturated aqueous sodium bicarbonate (2×5 L), once with water (1×5 L) and finally once with brine (1×5 L). The organic phase was evaporated under reduced pressure to give 972 g of a brown oil as crude product. The crude product was purified by flash chromatography using ethyl acetate / heptane (5% to 70% ethyl acetate gradient) as eluent to give 740 g of 6 as a pale yellow foam.

[0065] <Step 7: Boc deprotection> [Table 8]

[0066] <Preparation> A solution of EtOAc (1050 ml) and MeOH (272 ml) was cooled to 0° C., and acetyl chloride (534 g, 6.67 mmol, 10.3 eq.) was added dropwise over 40 min. The solution was stirred at room temperature for 1 h. The solution was then cooled again to 0° C., and a solution of 6 (484 g, 0.647 mol, 1 eq.) in ethyl acetate (480 mL) was added slowly over 20 min. The resulting reaction mixture was stirred at 0° C. for 5 min, then at room temperature for 2 h.

[0067] The reaction mixture was then first concentrated at 30° C. (to remove HCl) and then concentrated at 40° C. to give 457 g of 7 as a pale yellow solid.

[0068] <Step 8: TFA-Gly group introduction> [Table 9]

[0069] <Preparation> A solution of 7 (455g, 0.652mol, 1eq.) in acetonitrile (1200mL) was stirred at room temperature for 10 minutes. A solution of 2-(trifluoroacetamido)acetyl chloride (213g, 0.989mol, 1.52eq.) in acetonitrile (1100mL) was added and cooled to 0°C. DIPEA (290ml, 1.66mol, 2.55eq.) was added dropwise over 25 minutes. The resulting reaction mixture was stirred at 0°C for 5 minutes and then at room temperature for 1 hour.

[0070] The reaction mixture was quenched by the addition of MeOH (52 ml, 1.30 mol, 2 eq.).

[0071] The dark orange reaction mixture was diluted with iPrOAc (2 L) and 1 M aqueous HCl (2 L). The organic phase was then washed with water (2 L), NaHCO3 1 / 2 saturated:brine (2 L:0.5 L) and finally with brine (1 L).

[0072] The organic phase was partially concentrated under reduced pressure (half of the volume removed).

[0073] Pyridine (107 ml, 1.305 mol, 2 eq.) was added to the crude product, followed by acetic anhydride (95 ml, 0.979 mol, 1.5 eq.) and dimethylaminopyridine (8.2 g, 65 mmol, 0.1 eq.) The reaction mixture was stirred at room temperature for 16 hours.

[0074] The dark orange reaction mixture was diluted with iPrOAc (2 L) and 1 M aqueous HCl (2 L). The organic phase was then washed with water (2 L), NaHCO3 1 / 2 saturated:brine (2 L:0.5 L) and finally with brine (1 L).

[0075] The organic phase was concentrated under reduced pressure to give 569.6 g of 8 as a dark brown foam.

[0076] <Step 9: Removal of thiophenol group> [Table 10]

[0077] <Preparation> The above 8 (715 g, 0.7895 mol, 1 eq.) was dissolved in acetonitrile (3200 mL) and water (71 mL, 3.947 mol, 5 eq.). The reaction mixture was cooled to 0° C. and N-iodosuccinimide (272 g, 1.184 mol, 1.5 eq.) was added. The resulting reaction mixture was stirred at 0° C. for 1 h.

[0078] The reaction mixture was diluted with 7% aqueous sodium thiosulfate (3.2 L). The solution was stirred at 0° C. for 5 minutes and then diluted with ethyl acetate (3200 ml). The organic phase was washed with 7% aqueous sodium thiosulfate and then once with saturated aqueous sodium bicarbonate (3200 ml). The organic phase was evaporated to dryness under reduced pressure at 40° C. to give 870 g of an orange gum.

[0079] The crude product was purified by flash chromatography using ethyl acetate / heptane (20% to 100% ethyl acetate gradient) as eluent to give 659 g of 9 as a white foam.

[0080] <Step 10: Introduction of phosphite group> [Table 11]

[0081] <Preparation> A suspension of 5-phenyl-1H-tetrazole (182 g, 1.236 mol, 3 eq.) in acetonitrile (950 ml) was cooled to 0° C. Dibenzyl N,N-diisopropylphosphoramidite (282 mL, 0.824 mol, 2 eq.) was added, followed by the dropwise addition of a solution of 9 (336 g, 0.412 mol, 1 eq.) in acetonitrile (450 mL) at 0° C. over 30 min. The resulting reaction mixture was allowed to stir at 0° C. for 30 min.

[0082] The reaction mixture was diluted with ethyl acetate (4200 mL). The resulting organic phase was washed with saturated aqueous sodium bicarbonate (2×4200 mL), saturated aqueous ammonium chloride (4200 mL), and then with brine (4200 mL). The organic phase was dried over sodium sulfate, filtered, and evaporated to dryness under reduced pressure to give 571 g of crude product as a pale orange oil.

[0083] The crude product was dissolved in ethyl acetate (500 mL). Heptane (4500 mL) was added dropwise at room temperature and the resulting suspension was stirred at room temperature for 1 h. The solid was filtered, washed three times with heptane (3×600 ml) and dried under reduced pressure to give 402.6 g of 10 as a pale orange solid.

[0084] <Step 11: Oxidation> [Table 12]

[0085] <Preparation> The above 10 (395 g, 0.355 mol, 1 eq.) was dissolved in acetonitrile (1170 mL). A 5.66 M solution of tert-butyl hydroperoxide in decane (94 mL, 0.533 mmol, 1.5 eq.) was added dropwise to the above solution over 8 min at 0° C. The resulting reaction mixture was stirred at 0° C. for 20 min and then at room temperature for 3 h.

[0086] The reaction mixture was poured into ethyl acetate (280 mL). 15 wt % aqueous sodium thiosulfate (3600 mL) and saturated aqueous sodium bicarbonate (15 mL) were added and the resulting mixture was vigorously stirred at room temperature for 2.5 hours. The phases were separated. The organic phase was washed with brine (3600 mL), dried over sodium sulfate, filtered and evaporated to dryness under reduced pressure to give 432 g of crude product as a yellow oil.

[0087] The crude product was suspended in isopropanol (2350 ml) and heated to 40° C. until a clear solution was obtained. The solution was then cooled to room temperature and stirred overnight. The suspension was diluted with diisopropyl ether (1175 ml) and stirred at room temperature for an additional 5 min. The precipitated solid was filtered, washed twice with 5% isopropanol in diisopropyl ether (2×500 ml), and then dried under reduced pressure at 40° C. to give 280.2 g of 11 as a white solid.

[0088] <Step 12: Debenzylation> [Table 13]

[0089] <Preparation> The above 11 (100 g, 0.1055 mol, 1 eq.) was dissolved in tetrahydrofuran (300 mL) and ethanol (700 ml) at 0° C. Pd / C (11.7 g, 10.55 mmol, 0.1 eq.) was added under an argon atmosphere. The resulting suspension was hydrogenated at room temperature for 4.5 h. After 3.5 h of reaction, triethylamine (16.3 ml, 0.1160 mmol, 1.1 eq.) was added.

[0090] The reaction mixture was filtered through a pad of Celite. The solid was washed twice with ethanol (2×500 mL). The resulting solution was evaporated to dryness and coevaporated once with tetrahydrofuran (500 mL) to give 92.4 g of a white foam.

[0091] The crude product was dissolved in tetrahydrofuran (500 ml). Diisopropyl ether was added dropwise over 30 minutes, followed by triethylamine (7.4 ml, 52.7 mmol, 0.5 eq.). The suspension was stirred at room temperature for 1 hour and 15 minutes. The precipitated solid was filtered, washed with tetrahydrofuran:diisopropyl ether 1:1 (4×100 ml), and then dried at 40° C. under reduced pressure to give 77.4 g of 12 as a white solid.

[0092] <Step 13: Triacetyl-cytidine coupling> [Table 14]

[0093] <Preparation> The triethylamine salt of 12 (97.5 g of compound with 70.4% free acid content, 0.1027 mol, 1 eq.) was added to a suspension of 3A molecular sieves (29.3 g) in acetonitrile (490 ml) under an argon atmosphere. To this solution was added 4-dimethylaminopyridine (25.6 g, 0.2054 mol, 2.0 eq.) and 1,1'-carbonyldiimidazole (23.89 g, 0.1540 mol, 1.5 eq.). The reaction mixture was stirred at room temperature under argon. After 15 min, 31P NMR from an aliquot of the reaction mixture indicated complete activation of 12. The reaction mixture was cooled to 0°C. 1,1'-carbonyldiimidazole (1.59 g, 10.27 mmol, 0.1 eq.) and 2',3'-O,N 4 -Triacetyl-cytidine (68 g, 0.1643 mol, 1.6 eq.) was added to the suspension. The reaction mixture was stirred under argon at 0° C. and the progress of the reaction was followed by 31P NMR.

[0094] The reaction mixture was filtered through a pad of Celite and the solid was washed with dry acetonitrile (2 x 25 ml). The filtrate was kept at 0°C during filtration. The combined cold filtrates were added dropwise to a vigorously stirred solution of isopropyl acetate (5500 mL) under argon over 34 min. The resulting suspension was stirred at room temperature under argon for 15 min. The solid was filtered under argon atmosphere and washed with isopropyl acetate (5 x 500 mL). The white solid was dried under vacuum at room temperature for 1.5 h to give 164.61 g of 13 as a white solid.

[0095] <Step 14: Acetyl and trifluoroacetamide deprotection> [Table 15]

[0096] <Preparation> 13 (164.61 g, 0.1123 mol, 1 eq.) was dissolved in cold methanol (0° C., 375 mL). This cold solution was added dropwise to a cooled solution of 2N aqueous NaOH (750 mL, 13.4 eq.; internal temperature: −7° C.) over 20 min (internal temperature at end of addition: 5° C.). The resulting solution was stirred at 0° C. for 1 h.

[0097] The reaction mixture was added dropwise to stirred ethanol (7500 mL) over 20 min. The precipitated solid was filtered, washed twice with ethanol (2×500 mL), and dried under reduced pressure at 20° C. for 1.5 h to give 81.58 g of a white solid.

[0098] The white solid (81.58 g) was dissolved in a cold aqueous solution of 0.005 N NaOH (0° C., 245 ml). The resulting solution was added dropwise to a stirred solution of methanol (1890 mL) over 5 min. The resulting suspension was cooled slowly to −7° C. (cooling gradient = −1° C. / min) and stirred at −7° C. overnight. The suspension was filtered, washed three times with cold methanol (0° C., 3×120 ml), and dried under high vacuum pump at room temperature for 6.5 h to give 73.19 g of 14 as a white solid.

[0099] <Example 2> In some embodiments, the process comprises the benzylation of N-acetylneuraminic acid. In some embodiments, the process of the present invention comprises the 14-step process of Example 1, where the benzylation reaction is as follows:

[0100] <Benzylation> [Table 16]

[0101] N-Acetylneuraminic acid (5 g, 0.0161 mol, 1 eq.) was suspended in N,N-dimethylacetamide (25 mL). Cesium carbonate (3.1 g, 0.010 mol, 0.59 eq.) was added. The resulting suspension was stirred at room temperature for 1.25 h. Benzyl bromide (3.0 mL, 0.024 mol, 1.52 eq.) was added dropwise over 10 min. The reaction mixture was stirred at room temperature for 16 h. The reaction mixture was used directly in the next step.

[0102] <Example 3> In some embodiments, the process of the present invention includes an acetylation step. In some embodiments, the process includes the 14-step process of Example 1 and Example 2, where the acetylation step of compound 1 is as follows:

[0103] <Acetylation> [Table 17]

[0104] <Adjustment> The reaction mixture from the previous step was cooled to 0° C. 4-Dimethylaminopyridine (0.32 g, 0.003 mol, 0.16 eq.) and pyridine (13.0 mL, 0.161 mol, 10 eq.) were added. Acetic anhydride (12.3 mL, 0.129 mol, 8 eq.) was added dropwise over 15 min at 0° C. The reaction mixture was stirred at room temperature for 24 h.

[0105] The reaction mixture was diluted with isopropyl acetate (50 mL). The resulting organic phase was washed successively with 1N aqueous HCl (2×125 mL), saturated aqueous sodium bicarbonate (2×125 mL), and water (125 mL). The organic layer was evaporated under reduced pressure to give 7.74 g of a sticky off-white foam.

[0106] The crude product was dissolved in ethyl acetate (10 mL). Heptane (40 mL) was added dropwise at room temperature and the resulting suspension was stirred at room temperature for 1 h. The solid was filtered, washed three times with heptane / EtOAc 9 / 1 (3×10 ml) and dried under reduced pressure to give 6.59 g of 2 as a white solid.

Claims

1. 1. A method for synthesizing cytidine-5′-monophospho-N-glycyl-sialic acid (GSC), comprising: A method comprising two or more steps, the first of which comprises benzylation of N-acetylneuraminic acid.

2. 2. The method of claim 1, wherein the first step comprises synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate.

3. The method of claim 1, wherein the two or more steps include a step of synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof.

4. The two or more steps include: synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-5-acetamido-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-[acetyl(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-(tert-butoxycarbonylamino)-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium chloride; synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl (2S,4S,5R)-4-acetoxy-2-hydroxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphanyloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing [(2R,4S,5R)-4-acetoxy-2-carboxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-yl]hydrogenphosphate;triethylammonium; synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof; The method of claim 1 , comprising:

5. 1. A method for synthesizing cytidine-5′-monophospho-N-glycyl-sialic acid (GSC), comprising: synthesizing benzyl (2S,4S,5R)-5-acetamido-2,4-dihydroxy-6-[(1R,2R)-1,2,3-trihydroxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-5-acetamido-2,4-diacetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-5-acetamido-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-[acetyl(tert-butoxycarbonyl)amino]-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-5-(tert-butoxycarbonylamino)-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-2-carboxylate; synthesizing [(3R,4S,6R)-4-acetoxy-6-benzyloxycarbonyl-6-phenylsulfanyl-2-[(1S,2R)-1,2,3-triacetoxypropyl]tetrahydropyran-3-yl]ammonium chloride; synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-phenylsulfanyl-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl (2S,4S,5R)-4-acetoxy-2-hydroxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphanyloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing benzyl (2R,4S,5R)-4-acetoxy-2-dibenzyloxyphosphoryloxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylate; synthesizing [(2R,4S,5R)-4-acetoxy-2-carboxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-yl]hydrogenphosphate;triethylammonium; synthesizing (2R,4S,5R)-2-[[(2R,4S,5R)-5-(4-acetamido-2-oxo-pyrimidin-1-yl)-3,4-diacetoxy-tetrahydrofuran-2-yl]methoxy-hydroxy-phosphoryl]oxy-4-acetoxy-6-[(1S,2R)-1,2,3-triacetoxypropyl]-5-[[2-[(2,2,2-trifluoroacetyl)amino]acetyl]amino]tetrahydropyran-2-carboxylic acid or a salt thereof; or any combination of the above steps; A method comprising:

6. 6. The method of claim 5, wherein the starting material is N-acetylneuraminic acid.

7. The method of claim 1, further comprising one or more of acetylation, thiophenol group introduction, Boc protection, deacetylation, Boc deprotection, TFA-Gly group introduction, thiophenol group removal, phosphite group introduction, debenzylation, triacetyl-cytidine coupling, and acetyl and trifluoroacetamide deprotection reactions.

8. 1. A process for the preparation of cytidine-5′-monophospho-N-glycyl-sialic acid (GSC), comprising: a. Benzylation of N-acetylneuraminic acid (Neu5AC) to obtain intermediate 1; 【Chemistry 15】 b. Acetylation of intermediate 1 to obtain intermediate 2; 【Chemistry 16】 c. Introduction of a thiophenol group into intermediate 2 to obtain intermediate 3; 【Chemistry 17】 d. Boc protection of intermediate 3 to give intermediate 4; [Chemistry 18] e. Deacetylation of intermediate 4 to obtain intermediate 5 (wherein R = H or acetyl); 【Chemistry 19】 f. Acetylation of intermediate 5 to obtain intermediate 6; 【Chemistry 20】 g. Boc deprotection of intermediate 6 to give intermediate 7; 【Chemistry 21】 h. introducing a TFA-Gly group into intermediate 7 to obtain intermediate 8; 【Chemistry 22】 i. Removal of the thiophenol group from intermediate 8 to obtain intermediate 9; 【Chemistry 23】 j. introducing a phosphite group into intermediate 9 to obtain intermediate 10; 【Chemistry 24】 k. Oxidation of intermediate 10 to obtain intermediate 11; 【Chemistry 25】 l. Debenzylation of intermediate 11 to obtain intermediate 12; 【Chemistry 26】 m. triacetyl-cytidine coupling of intermediate 12 to obtain intermediate 13; 【Chemistry 27】 n. Acetyl and trifluoroacetamide deprotection of intermediate 13; 【Chemistry 28】 The process includes:

Images