CN112625220A - Method for preparing protecting group-free same (different) type sugar-containing polymer by ROMP polymerization reaction - Google Patents

Abstract

The invention relates to a method for preparing a protective group-free homo (iso) saccharide-containing polymer by ROMP polymerization, which comprises the steps of firstly combining Michael addition reaction to prepare a double-terminal alkyne compound in a proper solvent, and then using copper-catalyzed click chemistry reaction in methanol at room temperature to obtain a norbornene derivative of a protective group-free iso-saccharide monomer. Then under the action of Grubbs third-generation catalyst, ring-opening metathesis polymerization is carried out, and the sugar-containing polymer of the same (different) type without protective group with controllable molecular weight and narrow molecular weight distribution is successfully prepared in N, N-dimethylformamide solvent at 50 ℃. The invention provides a feasible way for artificially synthesizing the same (different) type sugar-containing polymer without the protecting group with ordered side chain structure, and has important significance for the research of the sugar-containing polymer without the protecting group.

Description

Method for preparing protecting group-free same (different) type sugar-containing polymer by ROMP polymerization reaction

Technical Field

The invention belongs to the technical field of synthesis of protecting group-free homo (hetero) sugar-containing polymers, and relates to a method for preparing protecting group-free homo (hetero) sugar-containing polymers by ROMP polymerization reaction.

Background

Sugar-containing polymers (glycopolymers) are a class of synthetic macromolecules that will contain sugar groups and have good water solubility, biological stain resistance, molecular recognition, and good "sugar clustering". Since a series of sugar-containing polyacrylamides were synthesized by a radical polymerization method in 1978 for the first time, with the rapid development of polymer synthesis chemistry, particularly the synthesis technology of functional sugar polymers, several strategies for controlled radical polymerization (e.g., reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxide-controlled radical polymerization (NMP), copper-catalyzed living radical polymerization (TMM-LRP, ATRP, and SET-LRP) have been continuously developed, utilized, and improved to prepare sugar-containing polymers with better properties and controllable components and structures. The research of artificially synthesizing the sugar-containing polymer is very important for the application of the sugar material and the theoretical research.

At present, the research on the synthesis method of sugar-containing polymers is mainly based on the two aspects of the polymerization of glycosylated monomers and the post-polymerization modification of polymer main chains and sugar-containing derivatives. The polymerization of the glycosylation monomer refers to that the polymer obtains the glycosyl function and the characteristics of other functional groups by utilizing the homopolymerization of the sugar-containing monomer or the copolymerization of the sugar-containing monomer and other functional monomers, thereby meeting the requirements of specific applications and obtaining the deprotected sugar-containing polymer without a complicated purification process. Meanwhile, Ring Opening Metathesis Polymerization (ROMP) can prepare polymers with narrow molecular weight distribution and uniform molecular structure. However, the synthesis route of the sugar monomer without the protecting group is complex, the required monomer has high purity and is expensive, the sugar monomer without the protecting group has certain insolubility in an organic solvent, and the reaction condition requires harsh polymerization conditions, so that further research and development are needed for the ROMP reaction of the sugar monomer without the protecting group in a homogeneous solvent.

Disclosure of Invention

The invention aims to provide a method for preparing a protecting group-free homo (hetero) saccharide-containing polymer by ROMP polymerization reaction so as to artificially synthesize a protecting group-free homo (hetero) saccharide-containing polymer with ordered side chain structures.

The purpose of the invention can be realized by the following technical scheme:

a method for preparing a protecting group-free same (different) type sugar-containing polymer by ROMP polymerization reaction comprises the step of carrying out ROMP polymerization reaction on a protecting group-free same (different) type sugar monomer and a Grubbs third-generation catalyst in an N, N-Dimethylformamide (DMF) solvent under an inert gas atmosphere to obtain a target product.

Further, the temperature of ROMP polymerization reaction is 40-60 ℃, and the reaction time is 12-18 h.

Furthermore, the molar ratio of the same (different) sugar monomer without the protecting group to the Grubbs third-generation catalyst is 10-15: 1.

Further, after the monomers are completely polymerized, adding vinyl ethyl ether to terminate the polymerization reaction, and performing post-treatment on the obtained reaction product to obtain a target product, wherein the post-treatment process specifically comprises the following steps: adding methanol into the reaction solution, stirring and settling, washing and drying the precipitated solid, and obtaining the target product.

Further, the non-protecting group iso (iso) sugar monomer is alpha-D-mannose-containing monomer (i.e. M)₁Man + Man), beta-D-glucose monomer (i.e., M)₂Man + β Glu) or β -D-galactose monomer (i.e., M)₃Man + β Gal), i.e. the chemical structural formulae respectively as follows:

further, the protecting group-free iso (iso) saccharide monomer is prepared by the following method:

(1) reacting furan and maleic anhydride in a solvent at room temperature to generate a compound 1;

(2) reacting the compound 1 with ethanolamine in methanol to generate a compound 2;

(3) reacting the compound 2, TDC, N' -dicyclohexylcarbodiimide and 4-dimethylaminopyridine in dichloromethane to generate a compound 3;

(4) compound 3 and Dowex-H⁺Reacting the resin at normal temperature to generate a compound 4;

(5) reacting the compound 4, 4-pentanoic anhydride and 4-dimethylamino pyridine in dichloromethane to generate a compound 5;

(6) the compound 5 and 1-azido-alpha-D-mannopyranose react in methanol under the catalysis of cuprous chloride at normal temperature to generate a compound M₁And compound M' (i.e., Man + Alkyne);

(7) dissolving the compound M' and 1-azido-beta-D-glucopyranose in methanol, adding cuprous chloride as a catalyst, stirring at normal temperature, filtering to remove insoluble substances, washing with methanol, and performing column chromatography to obtain the compound M₂；

(8) Dissolving the compound M' and 1-azido-beta-D-galactopyranose in methanol, adding cuprous chloride as catalyst, stirring at normal temperature, filtering to remove insoluble substances, washing with methanol, and performing column chromatography to obtain compound M₃；

The resulting Compound M₁Compound M₂And a compound M₃Namely alpha-D-mannose monomer, beta-D-glucose monomer or beta-D-galactose monomer;

the chemical structure of compound M' is as follows:

furthermore, in the step (1), the molar ratio of the maleic anhydride to the furan is (0.2-0.4): 1, the reaction process is specifically as follows: the reaction was carried out at room temperature for 24 h.

Further, in the step (2), the molar ratio of the compound 1 to the ethanolamine is (200-): 1, the reaction process is specifically as follows: the mixture was stirred at 0 ℃ for 1 hour and then reacted at room temperature for 1 hour.

Furthermore, in the step (3), the mass ratio of the compound 2, TDC, N' -dicyclohexylcarbodiimide and 4-dimethylaminopyridine is (9-12): (8-12): (14-18): 1.6;

the reaction process specifically comprises the following steps: stirred at room temperature for 24 h.

Further, in step (5), the molar ratio of compound 4, 4-pentanoic anhydride and 4-dimethylaminopyridine is 1: (2-4): (0.4-0.6);

the reaction process specifically comprises the following steps: the reaction was stirred at room temperature for 16 h.

Further, in the step (6), the molar ratio of the compound 5, 1-azido-alpha-D-mannopyranose to cuprous chloride is 1: (0.8-1.2): (1.5-2.5);

in the step (7), the molar ratio of the compound M', 1-azido-beta-D-glucopyranose to cuprous chloride is 1: (1.0-1.4): (2.5-3.5);

in the step (8), the molar ratio of the compound M', the 1-azido-beta-D-galactopyranose and the cuprous chloride is 1: (1.0-1.4): (2.5-3.5).

The invention selects three monosaccharides prepared by early stage experiments: alpha-D-mannose monomer, beta-D-glucose monomer and beta-D-galactose monomer. Importantly, in the preparation of the sugar-containing monomer, a stronger acylating agent 4-valeric anhydride is selected, and the acylating agent is suitable for phenolic hydroxyl which is difficult to react by a direct esterification method or hydroxyl compounds with larger steric hindrance. Secondly, in order to seek a reaction capable of generating a complex compound, cuprous chloride is selected as a catalyst to react in a methanol solution at normal temperature, so that the problems that sugar without a protecting group is difficult to dissolve in an organic solvent, and the hydrolysis of ester is inhibited by adding alcohol into a reaction system are solved, and the sugar monomer without the protecting group and the (different) type is obtained by reacting at room temperature. Then, ring-opening metathesis polymerization is carried out, and the same (different) type sugar-containing polymer which has regular structure, controllable molecular weight and narrow molecular weight distribution and contains no protecting group is prepared in N, N-dimethylformamide solvent under the environment of 50 ℃ under the action of Grubbs third-generation catalyst.

The method is simple, efficient and convenient to operate, different glycosyl units are introduced into the same monomer, and the side chain structure is controllable. The invention solves the disadvantages of introducing heterogeneous sugar units by post-modification and block copolymerization methods, improves the difficulty of homogeneous polymerization of sugar-containing monomers without protective groups, and widens the synthetic route of sugar-containing polymers.

Compared with the prior art, the invention has the following advantages:

(1) the invention selects 4-valeric anhydride as an acylating agent for the first time and selects cuprous chloride as a catalyst, thereby effectively improving the problem of ester hydrolysis, successfully preparing three protecting group-free same (different) type sugar-containing monomers, and having stable and high-efficiency synthesis method.

(2) The invention uses Grubbs three-generation catalyst at 50 ℃ for the first time to prepare the sugar-containing polymer containing the same (different) type sugar monomer without the protecting group, which has regular structure, controllable molecular weight and narrow molecular weight distribution through ring-opening metathesis polymerization. The invention solves the disadvantages of introducing heterogeneous sugar units by post-modification and block copolymerization methods, and widens the synthetic route of the sugar-containing polymer.

(3) The heterogeneous carbohydrate-containing polymer synthesized by the invention has controllable side chain structure and regular structure, can be applied to the research of biological protein specificity identification, and can also be used for preparing biological diagnostic materials with special functions.

Drawings

FIG. 1 shows the reaction of alpha-D-mannosylazide in CDCl₃In (500MHz)¹H NMR。

FIG. 2 shows beta-D-glucopyranosyl azide in CDCl₃In (500MHz)¹H NMR。

FIG. 3 shows beta-D-galactosylalkylazide in CDCl₃In (500MHz)¹H NMR。

FIG. 4 shows the reaction of Compound 5 in CDCl₃In (500MHz)¹H NMR。

FIG. 5 shows the reaction of Compound 5 in CDCl₃In (125MHz)¹³C NMR。

FIG. 6 shows Compound M₁At D₂In O (500MHz)¹H NMR。

FIG. 7 shows Compound M₁At D₂In O (125MHz)¹³C NMR。

FIG. 8 shows the compound M' at D₂In O (500MHz)¹H NMR。

FIG. 9 shows the compound M' at D₂In O (125MHz)¹³C NMR。

FIG. 10 shows Compound M₂At D₂In O (500MHz)¹H NMR。

FIG. 11 shows Compound M₂At D₂In O (125MHz)¹³C NMR。

FIG. 12 shows Compound M₃At D₂In O (500MHz)¹H NMR。

FIG. 13 shows Compound M₃At D₂In O (125MHz)¹³C NMR。

FIG. 14 shows sugar Polymer P (Man + Man) at D₂In O (500MHz)¹H NMR。

FIG. 15 shows sugar Polymer P (Man + β Glu) at D₂In O (500MHz)¹H NMR。

FIG. 16 shows the saccharide polymers P (Man +. beta. Gal) at D₂In O (500MHz)¹H NMR。

FIG. 17 is a gel chromatography chart of the protecting group-free homo (hetero) saccharide-containing polymer.

FIG. 18 is a schematic of the synthesis scheme of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

The invention is described in detail below with reference to the synthetic process scheme of FIG. 18.

In each of the following examples, three azido sugars (. alpha.Man-OAc-N)₃、βGal-OAc-N₃、βGlu-OAc-N₃) Synthesized according to the methods of the following two documents; maleic anhydride, a product of Hakka Adama reagents, Inc.; 4-pentanoic anhydride, a product of Hakka Adama reagent, Inc.; 4-dimethylaminopyridine, available from Haemax Agents, Inc. of Shanghai; (ii) a Dowex-H⁺Resins, products of shanghai hadamard reagents ltd; grubbs' third generation catalyst, product of Haicha Adama reagents, Inc.; 2,2, 5-trimethyl-1, 3-dioxane-5-carboxylic acid, a product of Shanghai Adama reagent, Inc.; all other raw materials are commercially available analytical reagents, wherein anhydrous methanol, anhydrous Dichloromethane (DCM) and anhydrous N, N-Dimethylformamide (DMF) (containing molecular sieve, water content is less than or equal to 0.05%) are all purchased from Shanghai Michelin Biochemical Co., Ltd. Among them, reference 1 is a. bianchi and a. bernardi, j.org.chem.,2006,71, 4565-; document 2 is V.Percec, P.Leowanawat, H.J.Sun, O.Kulikov, C.D.Nusbaum, T.M.Tran, A.Bertin, D.A.Wilson, M.Peterca, S.Zhang, N.P.Kamat, K.Vargo, D.Moock, E.D.Johnston, D.A.Hammer, D.J.Pochan, Y.Chen, Y.M.Charre, T.C.Shiao, M.Bergeron-Brlek, S.Andre, R.Roy, H.J.Gabius and P.A.Heiney, J.Am.Chem.Soc.,2013,135, 55.9077.9077.

Example 1

Synthesis of Compound 1

Maleic anhydride (50g, 0.51mol) was charged to a dry round bottom flask and 250mL of diethyl ether was added. After the maleic anhydride had dissolved, furan (125mL, 1.72mol) was added. After the reaction was completed for 24 hours at room temperature, ether and furan were removed by filtration, and washed three times with ether to obtain 76g of a white solid (i.e., compound 1) in 90% yield.

¹H NMR(500MHz,CDCl₃,ppm)δ＝6.54(s,2H),5.30(s,2H),3.80(m,2H),3.70(m,2H),2.91(s,2H),2.32(s,1H).

Example 2

Synthesis of Compound 2

Compound 1(10.8g, 51.6mmol) and methanol (210mL) were stirred at 0 ℃. Then ethanolamine (11mL,0.18mmol) is dissolved in 30mL of methanol and is dripped into the reaction system for no less than 30min, then the stirring is continued for 1h at the temperature of 0 ℃, the ice bath is removed, the reaction is carried out for 1h at the room temperature, and the heating is carried out for reflux for 12h at the temperature of 65 ℃. After the reaction was completed, the reaction mixture was cooled to room temperature, and then recrystallized after removing a large amount of methanol by distillation under reduced pressure, and the filtrate was washed with petroleum ether to obtain 16g of a white solid (i.e., compound 2) in a yield of 64%.

¹H NMR(500MHz,CDCl₃)δ＝6.52(s,2H),5.28(s,2H),3.76(s,2H),3.70(s,2H),2.89(s,2H),2.15(s,1H).

Example 3

Synthesis of Compound 3

TDC (2,2, 5-trimethyl-1, 3-dioxane-5-carboxylic acid) (9.0g, 51.6mmol) and compound 2(10.8g, 51.6mmol) were dissolved in 120mL of anhydrous dichloromethane. N, N' -Dicyclohexylcarbodiimide (DCC) (16g, 77.5mmol) and 4-Dimethylaminopyridine (DMAP) (1.6g, 13.1mmol) were then added and stirred at room temperature for 24 h. After filtration to remove insoluble impurities, the filtrate was concentrated and purified by petroleum ether/ethyl acetate 1: 1 as eluent, the viscous oil obtained after purification by column chromatography on silica gel, the product being dried in vacuo. 15.65g of a white solid (i.e., Compound 3) was obtained in 83% yield.

¹H NMR(500MHz,CDCl₃,ppm)δ＝6.51(s,2H),5.26(s,2H),4.29(t,J＝5.2Hz,2H),4.13(d,J＝11.8Hz,2H),3.78(t,J＝5.2Hz,2H),3.59(d,J＝11.8Hz,2H),2.86(s,2H),1.39(d,J＝17.7Hz,6H),1.18(s,3H).

Example 4

Synthesis of Compound 4

Dissolving compound 3(42.5g, 116mmol) in methanol, stirring at 35 deg.C for reaction, tracking reaction by TLC, adding appropriate amount of Dowex-H after reaction⁺The reaction solution was neutralized with a resin, the insoluble resin was removed by filtration, the filtrate was concentrated, and purification and separation were performed using a silica gel column (ethyl acetate 100%) to obtain 35.6g of a white solid (i.e., compound 4) in 94% yield.

¹H NMR(500MHz,CDCl₃,ppm)δ＝6.53(s,2H),5.28(s,2H),4.33(s,2H),3.83–3.76(m,4H),3.68(d,J＝11.4Hz,2H),2.91(s,2H),2.76(s,2H),1.04(s,3H).

Example 5

Synthesis of Compound 5

Compound 4(3.25g, 10mmol) was added to dry dichloromethane (40mL) with stirring, nitrogen purged, followed by 4-pentanoic anhydride (5.34g, 30mmol), 4-dimethylaminopyridine (0.66g, 5.4mmol), and pyridine (7.6 mL). Stirring at room temperature for 16h, monitoring the reaction by TLC, and using NaHSO to react the reaction solution₄The aqueous solution and saturated aqueous sodium bicarbonate solution were each washed three times, and the organic phase was dried over anhydrous sodium sulfate and directly passed through a silica gel column to give 4.4g of pale yellow 5 (i.e., compound 5) in 90% yield¹H NMR and¹³c NMR is shown in FIGS. 4 and 5.

¹H NMR(500MHz,CDCl₃)δ＝6.50(s,2H),5.28(s,2H),4.22(d,J＝12.5Hz,4H),4.17(s,2H),3.74(t,J＝5.0Hz,2H),2.87(s,2H),2.53(t,J＝7.0Hz,4H),2.49～2.41(m,4H),1.96(s,2H),1.21(s,3H).¹³C NMR(125MHz,CDCl₃)δ＝176.03,172.31,171.21,136.57,82.35,80.87,69.21,65.31,61.64,47.53,46.26,37.70,33.19,17.59,14.28.HRMS(ESI):C₂₅H₂₇NO₉H(M+H⁺)calc.for:486.171708；found:486.171934.

Example 6

Compound M₁Synthesis of (Man + Man)

Dissolving compound 5(1.00g, 2.06mmol) and 1-azido-alpha-D-mannopyranose (0.42g, 2.06mmol) in 8mL of methanol, adding cuprous chloride (0.41g, 4.12mmol), stirring at room temperature for 24h, monitoring by TLC until the reaction is complete, filtering to remove insoluble substances, washing with methanol, and passing through silica gel column directly to obtain a pale yellow oil M₁(Man + Man)1.07g, yield 58%, which is¹H NMR and¹³c NMR is shown in FIGS. 6 and 7; and 0.43g of compound M' in a yield of 30%, which is¹H NMR and¹³c NMR is shown in FIGS. 8 and 9.

Compound M₁：¹H NMR(500MHz,D₂O)δ＝8.04(s,2H),6.69(s,2H),6.16(s,2H),5.36(s,2H),4.27(d,J＝4.5Hz,2H),4.18(ddd,J₁＝21.5Hz,J₂＝10.0Hz,J₃＝3.5Hz,7H),3.88(ddd,J₁＝16.0Hz,J₂＝13.5Hz,J₃＝6.5Hz,10H),3.72(d,J＝7.0Hz,2H),3.40～3.34(m,2H),3.20(s,2H),3.10(t,J＝6.5Hz,5H),2.89(t,J＝6.5Hz,4H),1.16～1.12(m,3H).¹³C NMR(125MHz,D₂O)δ＝178.97,174.28,146.80,136.43,122.88,87.59,86.81,81.20,78.97,76.21,76.05,75.81,72.39,70.72,69.12,68.48,66.66,65.65,62.36,60.61,47.56,46.33,37.67,32.96,20.29,16.85.HRMS(ESI):C₃₇H₄₉N₇O₁₉H(M+H⁺)calc.for:896.31862；found:896.31631.

A compound M':¹H NMR(500MHz,D₂O)δ＝8.04(s,1H),6.60(s,2H),5.63(d,J＝9.0Hz,1H),5.30(s,2H),4.26～4.07(m,8H),3.98(t,J＝6.0Hz,1H),3.86(dd,J₁＝9.5Hz,J₂＝2.5Hz,1H),3.77(d,J＝6.0Hz,4H),3.11(s,2H),3.04(t,J＝7.0Hz,2H),2.82(t,J＝7.0Hz,2H),2.59(t,J＝6.5Hz,2H),2.46(d,J＝5.0Hz,2H),2.33(s,1H),1.15(s,3H).¹³C NMR(125MHz,D₂O)δ＝177.53,172.94,172.69,172.12,146.40,136.36,122.30,82.23,80.90,76.81,71.08,69.26,68.73,67.02,65.30,61.74,60.86,47.95,47.78,47.61,37.34,32.91,23.01,20.27,16.61,13.68.HRMS(ESI):C₃₁H₃₈N₄O₁₄H(M+H⁺)calc.for:691.24921；found:691.24638.

example 7

Compound M₂Synthesis of (Man + β Glu)

Dissolving compound M' (1.00g, 2.06mmol) and 1-azido-beta-D-glucopyranose (0.50g, 2.47mmol) in 8mL of methanol, adding cuprous chloride (0.61g, 6.18mmol), stirring at room temperature for 24h, monitoring by TLC until the reaction is complete, filtering to remove insoluble substances, washing with methanol, and passing through silica gel column directly to obtain a light yellow oil M₂(Man +. beta. Glu)1.12g, yield 61%, which¹H NMR and¹³c NMR is shown in FIGS. 10 and 11.

¹H NMR(500MHz,D₂O)δ＝8.05(s,2H),6.63(s,2H),5.72(s,2H),5.30(s,2H),4.17(d,J＝31.5Hz,4H),4.01～3.86(m,4H),3.70(dd,J₁＝41.0Hz,J₂＝32.0Hz,9H),3.53～3.45(m,2H),3.36(s,2H),3.12(s,2H),3.04(s,4H),2.82(s,3H),1.10(s,3H).¹³C NMR(125MHz,D₂O)δ＝179.24,174.48,174.30,147.08,136.72,123.04,86.77,81.11,76.31,70.79,68.60,66.77,65.75,62.42,60.69,47.65,46.42,37.84,33.10,20.36,16.89.HRMS(ESI):C₃₇H₄₉N₇O₁₉H(M+H⁺)calc.for:896.31625；found:896.31489.

Example 8

Compound M₃Synthesis of (Man + β Gal)

Reacting compound M₁' (1.00g, 2.06mmol) and 1-azido-beta-D-galactopyranose (0.50g, 2.47mmol) were dissolved in 8mL of methanol, followed by addition of cuprous chloride (0.61g, 6.18mmol), stirring at room temperature for 24h, TLC monitoring until the reaction was complete, filtration to remove insoluble material, washing with methanol and passing directly through a silica gel column to give M as a pale yellow oil₃(Man +. beta. Gal)1.16g, yield 63%, which¹H NMR and¹³c NMR is shown in FIGS. 12 and 13.

¹H NMR(500MHz,D₂O)δ＝8.06(s,1H),8.00(s,1H),6.65(s,2H),6.12(s,1H),5.74(d,J＝9.0Hz,1H),5.32(s,2H),4.24(s,2H),4.12(dd,J₁＝20.5Hz,J ₂＝14.5Hz,5H),4.02(s,1H),3.97～3.70(m,10H),3.67(t,J＝9.0Hz,1H),3.34(s,1H),3.15(s,2H),3.07(d,J＝5.0Hz,4H),2.85(s,4H),1.11(s,3H).¹³C NMR(125MHz,D₂O)δ＝178.94,174.20,174.11,146.88,136.50,122.87,86.62,81.00,76.15,70.55,68.43,66.61,65.59,62.27,60.43,60.43,47.50,46.26,37.68,32.87,20.19,16.68.HRMS(ESI):C₃₇H₄₉N₇O₁₉H(M+H⁺)calc.for:896.31921；found:896.31875.

Example 9

ROMP polymerization for preparing sugar-containing polymer of same (different) type without protecting group

In a vacuum glove box, a sugar-containing monomer M (0.1117mmol, M respectively) was weighed₁、M₂And M₃) And Grubbs' third generation catalyst (8.9mg, 0.0100mmol) into a 10mL reaction flask, followed by 1.5mL anhydrous DMF to dissolve completely, stirring at 50 deg.C for 18h, adding 0.1mL vinyl ethyl ether to the reaction flask after the reaction is over, and continuing stirringStirring for 30min, settling the reaction solution in 20mL of methanol solution (repeating for three times) to obtain gray solid, drying in a vacuum drying oven at 60 ℃ to constant weight, weighing, and obtaining the yield of 74-78%.

The prepared sugar polymers respectively correspond to a sugar polymer P (Man + Man), a sugar polymer P (Man + beta Glu) and a sugar polymer P (Man + beta Gal), and the sugar polymers are¹H NMR is shown in fig. 14-16, while the corresponding gel chromatogram is shown in fig. 17, and the Gel Permeation Chromatography (GPC) characterization is shown in table 1 below.

The number average molecular weight of the resulting polymer was 7.9X 10 by GPC measurement of the sugar-containing polymer without a protective group³～8.2×10³Within the range, the difference with a set value of the molecular weight of 10000 is not large, the molecular weight dispersion width is 1.08-1.10, the PDI value is small, the fluctuation is small, and the molecular weight is controllable, and FIG. 17 is a gel chromatogram of the prepared sugar-containing polymer.

Table 1Characterization of the glycopolymers via GPC

^aMolar ratio of[Glycomonomer(M)]/[Grubbs catalyst(G)].^bObtained by GPC.^cIsolated yield.

Compared with other polymerization methods of sugar-containing derivatives, the invention has the following innovations in the preparation of sugar-containing monomers and polymers:

in example 5:

since compound 5 contains an ester, it is not suitable to introduce a terminal alkyne into the terminal functional group by the conventional Williamson synthesis method, which generates a hydrogen halide to hydrolyze the ester. The invention creatively selects 4-valeric anhydride as an acylating agent, directly introduces terminal alkyne by an esterification method, is suitable for phenolic hydroxyl which is difficult to react or hydroxyl compounds with larger steric hindrance, does not hydrolyze ester, and has the yield as high as 90 percent.

In example 6:

the current CuAAC comparative classical reaction system is the reaction of blue vitriod and sodium ascorbate in a mixed solvent of tert-butyl alcohol and water, but the sodium ascorbate is alkaline, which can hydrolyze ester bonds in compound 5. Therefore, cuprous chloride is selected as a catalyst to react in a methanol solution at normal temperature, the problems that sugar without a protecting group is difficult to dissolve in an organic solvent, and the hydrolysis of ester is inhibited by adding alcohol in a reaction system are solved, so that the sugar monomer without the protecting group and the like (different) is obtained by reacting at room temperature.

In example 9:

because sugar monomers without protecting groups are insoluble in organic solvents, and the protic solvent has a certain inhibiting effect on the activity of Grubbs catalysts, ROMP of sugar monomers without protecting groups in homogeneous solvents is rarely reported. The invention selects a good aprotic solvent, namely N, N' -dimethylformamide, has good solubility, can dissolve sugar monomers without protecting groups, and does not inhibit the activity of the Grubbs catalyst. The sugar-containing polymer of the same type (different type) containing no protecting group with regular structure, controllable molecular weight and narrow molecular weight distribution is prepared by ring-opening metathesis polymerization under the action of Grubbs three-generation catalyst.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (10)

1. A method for preparing a protecting group-free iso (iso) saccharide-containing polymer by ROMP polymerization reaction is characterized in that under the atmosphere of inert gas, the protecting group-free iso (iso) saccharide monomer and a Grubbs three-generation catalyst are subjected to ROMP polymerization reaction in an N, N-dimethylformamide solvent to obtain a target product.

2. The method for preparing the sugar-containing polymer of the same (different) type without the protecting group by ROMP polymerization reaction according to claim 1, wherein the temperature of ROMP polymerization reaction is 40-60 ℃ and the reaction time is 12-18 h.

3. The method of claim 1, wherein the molar ratio of the sugar monomer of the sugar of the same (different) type without the protecting group to the Grubbs' tertiary catalyst is 10-15: 1.

4. The method of claim 1, wherein the non-protecting group homo (hetero) saccharide-containing monomer is a α -D-mannose monomer, a β -D-glucose monomer or a β -D-galactose monomer.

5. The method for preparing a protecting group-free sugar-containing polymer of the same (different) type by ROMP polymerization reaction according to claim 1 or 4, wherein the protecting group-free sugar-containing polymer of the same (different) type is prepared by the following method:

(1) reacting furan and maleic anhydride in a solvent at room temperature to generate a compound 1;

(2) reacting the compound 1 with ethanolamine in methanol to generate a compound 2;

(3) reacting the compound 2, TDC, N' -dicyclohexylcarbodiimide and 4-dimethylaminopyridine in dichloromethane to generate a compound 3;

(4) compound 3 and Dowex-H⁺Reacting the resin at normal temperature to generate a compound 4;

(5) reacting the compound 4, 4-pentanoic anhydride, 4-dimethylamino pyridine and pyridine in dichloromethane to generate a compound 5;

(6) compounds 5 and 1-StackThe nitrogen-alpha-D-mannopyranose is catalyzed by cuprous chloride in methanol at normal temperature to react to generate a compound M₁And compound M';

(7) dissolving the compound M' and 1-azido-beta-D-glucopyranose in methanol, adding cuprous chloride as a catalyst, stirring at normal temperature, filtering to remove insoluble substances, washing with methanol, and performing column chromatography to obtain the compound M₂；

(8) Dissolving the compound M' and 1-azido-beta-D-galactopyranose in methanol, adding cuprous chloride as catalyst, stirring at normal temperature, filtering to remove insoluble substances, washing with methanol, and performing column chromatography to obtain compound M₃；

The resulting Compound M₁Compound M₂And a compound M₃Namely alpha-D-mannose monomer, beta-D-glucose monomer or beta-D-galactose monomer;

the chemical structure of compound M' is as follows:

6. the process for preparing a protecting group-free sugar-containing polymer of the same (different) type by ROMP polymerization as claimed in claim 5, wherein the molar ratio of maleic anhydride to furan in the step (1) is (0.2-0.4): 1, the reaction process is specifically as follows: the reaction was carried out at room temperature for 24 h.

7. The method for preparing a protecting group-free sugar-containing polymer of the same (different) type by ROMP polymerization as claimed in claim 5, wherein the molar ratio of the compound 1 to ethanolamine in the step (2) is (200-): 1, the reaction process is specifically as follows: the mixture was stirred at 0 ℃ for 1 hour and then reacted at room temperature for 1 hour.

8. The process for preparing a protecting group-free sugar-containing polymer of the same (different) type by ROMP polymerization as claimed in claim 5, wherein in the step (3), the mass ratio of the compound 2, TDC, N' -dicyclohexylcarbodiimide and 4-dimethylaminopyridine is (9-12): (8-12): (14-18): 1.6;

the reaction process specifically comprises the following steps: stirred at room temperature for 24 h.

9. The process according to claim 5, wherein the molar ratio of the compound 4, 4-pentanoic anhydride and 4-dimethylaminopyridine in step (5) is 1: (2-4): (0.4-0.6);

the reaction process specifically comprises the following steps: the reaction was stirred at room temperature for 16 h.

10. The method for preparing a protecting group-free sugar-containing polymer of the same (different) type by ROMP polymerization reaction as claimed in claim 5, wherein the molar ratio of the compound 5, 1-azido- α -D-mannopyranose to cuprous chloride in the step (6) is 1: (0.8-1.2): (1.5-2.5);

in the step (7), the molar ratio of the compound M', 1-azido-beta-D-glucopyranose to cuprous chloride is 1: (1.0-1.4): (2.5-3.5);

in the step (8), the molar ratio of the compound M', the 1-azido-beta-D-galactopyranose and the cuprous chloride is 1: (1.0-1.4): (2.5-3.5).

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