100 results about "Ester hydrochloride" patented technology

The invention belongs to the field of detection and analysis, and relates to a method for separating and detecting enantiomers in (S)-2-amino-3-[2-(tert-butoxy)-2-oxoacetamido] tert-butyl propionate hydrochloride. According to the method, HPLC is adopted for separation and detection, a polysaccharide derivative chiral chromatographic column is selected as a chromatographic column, a mobile phase A is a weak base aqueous solution, and a mobile phase B is acetonitrile and / or methanol. The method is strong in specificity, high in separation degree, high in accuracy, stable, reliable and high in sensitivity, and a simple, accurate, rapid and reliable detection method is provided for control of impurities in a starting material of (S)-2-amino-3-[2-(tert-butoxy)-2-oxoacetamido] tert-butyl propionate hydrochloride.

The invention discloses a method for synthesizing a high-purity pseudo proline dipeptide heterocyclic ring. The method comprises the following steps: (1) preparing L-serine or L-threonine into corresponding methyl ester hydrochloride; (2) condensing the methyl ester hydrochloride obtained in the step (1) with a condensation reagent to form a corresponding pseudo proline ring; and (3) condensing the pseudo-proline ring formed in the step (2) and related amino acid protected by Fmoc to obtain the corresponding pseudo-proline dipeptide heterocyclic ring. The total yield of the target product synthesized by the reaction can reach more than 80%. The method solves the problems of long reaction time, low yield, high safety risk and the like in the reported route, and has the advantages of cheap and easily available raw materials, lower production cost, simplicity in operation, environmental friendliness, high yield, short reaction time, simplicity in post-treatment and the like.

The invention provides a preparation method of a cross-linking agent, the cross-linking agent and application of the cross-linking agent, a precursor HAPCP is prepared from phosphonitrilic chloride trimer and p-hydroxybenzaldehyde, then chain extension is performed on the precursor HAPCP and aminoethyl acrylate hydrochloride to obtain a solid substance D, and finally, the target cross-linking agent is prepared from the solid substance D and DOPO. The molecular formula of the target cross-linking agent is C150H138N9O24P9, the cross-linking agent prepared by the process contains two flame-retardant groups, namely cyclotriphosphazene and DOPO, and also contains a large amount of acrylate groups, and in the production process of the flame-retardant unsaturated polyester resin, the flame-retardant unsaturated polyester resin has excellent flame-retardant property and flame-retardant property. Two non-halogen flame-retardant groups, namely cyclotriphosphazene and DOPO, can be simultaneously introduced into an unsaturated polyester resin matrix through the cross-linking agent, the flame retardance of the flame-retardant unsaturated polyester resin can be remarkably improved under the synergism of the two flame-retardant groups, the cross-linking requirement of unsaturated polyester can be met, the flame-retardant property requirement can also be met, and the cross-linking agent has the advantages of being high in applicability, low in cost and the like. The method conforms to the green chemistry concept and is convenient to popularize and implement.

The invention discloses a preparation process of rebamipide tablets, and relates to the technical field of pharmaceutical preparations. When preparing rebamipide tablets, the present invention first reacts BOC-lysine tert-butyl ester hydrochloride with isocyanoethyl methacrylate to obtain lysine monomer; lysine monomer is reacted with terminal 2-bromoisobutyrate polylactic acid to obtain an amino acid amphiphilic block copolymer; amino acid amphiphilic block copolymer is used to load rebamipide to obtain a loaded rebamipide amphiphilic copolymer; dopa is reacted with chitosan to obtain dopa-modified chitosan; dopa-modified chitosan and bismuth salt are film-coated on the surface of the loaded rebamipide amphiphilic copolymer to obtain dopa-modified chitosan-coated rebamipide, and then dopa-modified chitosan-coated rebamipide is made into tablets to obtain rebamipide tablets. The rebamipide tablets prepared by the present invention have the advantages of mucosal adhesion, long in vivo retention time, and high cellular uptake.

The invention discloses an injection containing methoxyetomidate hydrochloride and a preparation method of the injection. The injection comprises the following components: methoxyetomidate hydrochloride, a pH regulator, a solubilizing stabilizer and a solvent. The preparation method of the injection is simple and convenient for commercial production. A stability result shows that the product has good stability and is convenient for clinical application.

The invention provides a method for synthesizing N-methylated polypeptide, which comprises the following steps: dissolving a carboxylic acid compound, N-methyl amino-acid ester hydrochloride or N-methyl amino-acid ester, an alkaline substance and pivaloic anhydride in an organic solvent, reacting at 15-80 DEG C for 3-10 hours, and post-treating the obtained reaction liquid to obtain an N-methyl dipeptide compound, the method comprises the following steps: removing a protecting group in an N-methyl dipeptide compound to obtain a free-state N-methyl dipeptide compound, and condensing the free-state N-methyl dipeptide compound and amino acid or N-methyl amino-acid ester protected by amino to obtain the N-methylated polypeptide, the mixed anhydride intermediate is formed in situ, and the reaction is completed in one step; according to the method, trimethylacetic anhydride is used as a condensing agent, the structure is simple, the reaction is safe, cheap and non-toxic, a large amount of nitrogen-containing byproducts are not generated in the reaction, and purification is convenient; the method is high in stereoselectivity, and racemization is avoided; according to the method, environment-friendly solvents such as ethyl acetate can be used, the reaction condition is mild, and the reaction time is short.

The present invention relates to polymorphs of the hydrochloride salt of 5-{2-[({8-[(2,6-dimethylbenzyl)amino]-2,3-dimethylimidazo[1,2-a]pyridine-6-yl}carbonyl)-amino]ethoxy}-5-oxopentanoic acid (linaprazan glurate), more specifically Form 1 and Form 2 of the HCl salt of linaprazan glurate. The invention also relates to a process for the preparation of such polymorphs, to pharmaceutical compositions comprising such polymorphs, and to the use of these polymorphs in the treatment or prevention of gastrointestinal inflammatory diseases or gastric acid related diseases, in particular erosive gastroesophageal reflux disease (eGERD).

The invention discloses a polylysine ester hydrochloride and a preparation method and application thereof, and belongs to the field of chemical synthesis technology and biological application, the structural formula of the polylysine ester hydrochloride is as shown in # imgabs0 #, in the formula, R is selected from any one of alkyl groups with the carbon number smaller than 10, preferably methyl, ethyl, propyl, isopropyl, n-butyl or tertiary butyl; n ranges from 20 to 40; the preparation method of the polylysine ester hydrochloride provided by the invention is simple in steps and simple in subsequent treatment, and the prepared product polylysine ester hydrochloride has a certain antibacterial property and can be well applied to the fields of daily chemicals, foods, medicines, biology and the like.

The invention discloses an antifouling elastic sofa fabric and a preparation method thereof, and relates to the technical field of fabrics. Diphenylmethane diisocyanate, polypropylene oxide glycol and modified silicon dioxide are subjected to surface reaction to prepare a nano waterproof finishing agent, and the modified silicon dioxide is prepared by modifying sodium hydroxide, so that the antistatic effect of the fabric can be improved; dL-3-fluorophenylalanine methyl ester hydrochloride is grafted to cotton fibers, fluorine-containing groups of the DL-3-fluorophenylalanine methyl ester hydrochloride are greatly enriched on the surface of the fabric, the low surface energy of the fabric is reduced, stains are prevented from being attached to the surface of the fabric, the antifouling effect is achieved, meanwhile, DL-3-fluorophenylalanine methyl ester hydrochloride can be bonded with the nano waterproof finishing agent, a net-shaped cross-linked structure is formed, and the anti-fouling effect is achieved. The nano waterproof finishing agent is adsorbed into fibers of the fabric, so that the waterproof and antifouling effects of the fabric are further improved. The fabric prepared by the invention has waterproof and antifouling effects.

The invention provides a method for detecting chloroethane in hexyl aminolevulinate hydrochloride and application, the method comprises the following steps: preparing a reference solution and a test solution, the reference solution is a standard chloroethane solution, and the test solution is a hexyl aminolevulinate hydrochloride solution containing chloroethane; respectively injecting the reference solution and the test solution into a GC-MS (Gas Chromatography-Mass Spectrometer) by adopting a headspace sampling mode, and recording chromatograms; calculating the content of chloroethane in the test sample according to a peak area by an external standard method; the used gas chromatographic column is DB-FFAP, and the adopted gas chromatographic determination conditions are as follows: the flow of the chromatographic column is 1-10ml / min; the initial temperature of the column temperature is 25-50 DEG C, the initial temperature is maintained for 1-10 minutes, and the initial temperature is increased to 150-250 DEG C at the rate of 10-50 DEG C / min and maintained for 1-10 minutes; the temperature of a sample inlet is 150-30 DEG C; the sample size is 0.5 to 5 ml; the mass spectrum conditions are as follows: the operation time is 5-20 minutes; and the mass-to-charge ratio of chloroethane is 64 and 66. The method can be used for accurately and quickly detecting the content of chloroethane in hexyl aminolevulinate hydrochloride.

To provide a stable crystalline form of linaprazan glurate.SOLUTION: Provided are polymorphs of the hydrochloride salt of 5-{2-[({8-[(2,6-dimethylbenzyl)amino]-2,3-dimethylimidazo[1,2-a]pyridine-6-yl}carbonyl)amino]ethoxy}-5-oxopentanoic acid (linaprazan glurate).SELECTED DRAWING: None

The invention discloses a method for extracting bioactive substances from sheep placenta, and relates to the technical field of animal placenta extraction. The method uses immobilized lipase to enzymolyze the crushed fresh sheep placenta, then adds protease to continue enzymolysis, and after the enzyme is inactivated, the purified bioactive substances have a high yield; and the immobilized lipase prepared by the chitosan derivative modified by the thiazole group has good application stability; in addition, the present invention also uses S-benzyl-L-cysteine ​​methyl ester hydrochloride to undergo a substitution reaction with a polyamide nanofiltration membrane, and the obtained nanofiltration membrane is used in the purification process of the bioactive substance, which has a good decolorization effect.

The invention discloses trifluoromethyl benzyl ether substituted amino acid derivatives as well as a preparation method and application thereof, and belongs to the technical field of organic compound synthesis and medicine. The synthesis method of the trifluoromethyl benzyl ether substituted amino acid compound comprises the following steps: firstly, carrying out a Mitsunobu reaction on a benzyl alcohol compound and hydroxy naphthaldehyde (or hydroxy benzaldehyde), then generating Schiff base with amino-acid ester hydrochloride, then reducing with sodium cyanoborohydride, and then simply hydrolyzing to obtain the trifluoromethyl benzyl ether substituted amino acid compound. The preparation method provided by the invention has the characteristics of simple steps, mild reaction conditions and fast reaction, and meets the requirements of green chemistry. The compound prepared according to the method can selectively regulate the S1P1 receptor without exciting the S1P3 receptor, and is expected to be developed into a novel preparation for treating idiopathic pulmonary fibrosis.

The invention provides a method for synthesizing cyclic dipeptide, which comprises the following steps: (1) in the presence of a condensing agent, carrying out condensation reaction on amino acid of carbobenzoxy protected amino and amino acid methyl ester hydrochloride to generate chain dipeptide A retaining carbobenzoxy and methyl ester; and (2) in the presence of ammonium formate and palladium on carbon, removing protecting groups from amino acids and attacking ester bonds by amino groups to complete ring closing in one step, so as to obtain the cyclic dipeptide with the initial amino acid configuration reserved.

The invention provides a synthesis method of a medical intermediate (3R, 5R)-3-Boc-amino-5-fluoropiperidine, which comprises the following steps: step S1, trans-4-hydroxy-D-proline methyl ester hydrochloride is used as a raw material, under the action of triethylamine, a reaction is carried out for 2-4 hours, and the reaction product is subjected to post-treatment to obtain the (3R, 5R)-3-Boc-amino-5-fluoropiperidine. Dichloromethane is used as a solvent to react with triphenylchloromethane to obtain (4S)-4-hydroxy-1-(triphenylmethyl)-D-proline methyl ester; s2, the (4S)-4-hydroxy-1-(triphenyl methyl)-D-proline methyl ester is subjected to oxidation, and 4-oxy-1-(triphenyl methyl)-D-proline methyl ester is obtained; s3, enabling the compound 4-oxo-1-(triphenyl methyl)-D-proline methyl ester to react with hydroxylamine hydrochloride, so as to obtain a compound hydroxylamino-1-(triphenyl methyl)-D-proline methyl ester; step S9, the compound (3R, 5R)-3-Boc amino-1-triphenyl-5-fluoropiperidine is subjected to Trt removal under the action of hydrochloric acid, and a compound (3R, 5R)-3-Boc amino-5-fluoropiperidine is obtained; according to the method disclosed by the invention, the (3R, 5R)-3-Boc amino-5-fluoropiperidine can be efficiently and economically synthesized by optimizing a reaction route.

The invention discloses a preparation method of (2R, 3S)-2-Boc amino-3-hydroxy-3-(pyridine-4-yl) alanine, and belongs to the technical field of medical intermediates. The preparation method comprises the following steps: by taking glycine ester hydrochloride as a raw material, carrying out benzophenone dimethyl ketal reaction to generate a glycine ester imine intermediate; then, the 2-amino-3-hydroxyl-3-(pyridine-4-yl) alanine and pyridine-4-formaldehyde are subjected to acidolysis, and 2-amino-3-hydroxyl-3-(pyridine-4-yl) alanine is generated; then, the 2-Boc amino-3-hydroxyl-3-(pyridine-4-yl) alanine is subjected to a reaction with Boc2O, and a 2-Boc amino-3-hydroxyl-3-(pyridine-4-yl) alanine racemate is generated; and finally, salifying and resolving by adopting a cyclohexanedibenzylamine resolving agent, and then dissociating to obtain a target product. The raw materials are available in the market, direct condensation reaction is performed between pyridine-4-formaldehyde and amino acid imine, effective resolution can be performed by adopting 0.5 eq of a resolution reagent, and the whole route is simple and convenient to operate and suitable for large-scale production.

The invention discloses a 3-ester-1, 3-quinazoline-2, 4-diketone compound and a preparation method and application thereof.The 3-ester-1, 3-quinazoline-2, 4-diketone compound is prepared by the steps that amino-acid ester hydrochloride and isatoic anhydride serve as raw materials and react in acetonitrile under the action of potassium carbonate to generate an amide ester compound; and then reacting the amide ester compound with triphosgene under the action of triethylamine to obtain the 3-ester-1, 3-quinazoline-2, 4-diketone compound. Raw materials for synthesis of the compound are cheap and easy to obtain, the synthesis method is simple, meanwhile, the compound has good bacteriostatic activity on crop germs, especially has a remarkable activity inhibition effect on germs such as gibberellic disease bacteria, phytophthora germs, pyricularia grisea, sclerotinia sclerotiorum, botrytis cinerea and rhizoctonia solani, and the yield of crops is well guaranteed.

The invention discloses a synthesis method of a linker MC-Gly-Gly-Phe-Gly-OH, and the synthesis method comprises the following steps: taking Fmoc-Phe-OH and glycine tert-butyl ester hydrochloride as raw materials, and sequentially synthesizing a first intermediate Fmoc-Phe-Gly-OBu and a second intermediate H-Phe-Gly-OBu; the second intermediate and Boc-Gly-Gly-OH are sequentially synthesized into a third intermediate Boc-Gly-Gly-Phe-Gly-OBu and a fourth intermediate H-Gly-Gly-Phe-Gly-OH, and the fourth intermediate and 6-(maleimido) hexanoic acid succinimide ester are coupled to obtain the target product. The conditions of each step reaction are mild, the yield and purity of the intermediate are high, the HPLC purity of the obtained target product reaches 98% or above, the yield reaches 91% or above, the purity requirement of a medicine product is met, the method is suitable for industrial mass production, and the production cost is reduced.

The application belongs to the technical field of chemical industry, and discloses a synthesis method and application of (2R,4S)-4-hydroxypyrrolidine-2-carboxylic acid methyl ester hydrochloride, wherein trichloroisocyanuric acid is used as an oxidant, and silica gel loaded 2,2,6,6-tetramethylpiperidine oxide is added as a novel supported catalyst; the supported catalyst is removed and recovered through filtration to obtain an oxidation product IM1; then, sodium triacetoxyborohydride is used as a reducing agent to reduce a trans chiral ketone carbonyl to obtain a trans amino acid product IM2 which cannot be obtained through a fermentation method; finally, the target product (2R,4S)-4-hydroxypyrrolidine-2-carboxylic acid methyl ester hydrochloride is synthesized through a one-step synthesis method under a heating reaction condition in a methanol system. The product prepared through the method has high purity, low raw material cost, simple operation, and is suitable for industrial production and can meet the needs of the future medical and other fields.

The application discloses a tissue adhesive and a preparation method and application thereof, and belongs to the field of medical materials.The tissue adhesive comprises a copolymer composed of at least one of acrylic acid and methacrylic acid and a hydrochloride salt, the hydrochloride salt is at least one of 2-aminoethyl methacrylic acid ester hydrochloride and 2-aminoethyl acrylic acid ester hydrochloride, and the tissue adhesive can further comprise a crosslinked polymer formed by crosslinking at least one of polyacrylic acid and polymethacrylic acid with a polymer, and the polymer is formed by polymerization of the hydrochloride salt and a zwitterionic betaine.The copolymer can quickly absorb moisture on a wet tissue surface to form a gel and adhere to the tissue surface, so that a soft tissue wound, especially a low-pH microenvironment soft tissue wound, is closed; and the crosslinked polymer can be firmly combined on the surface of the copolymer and quickly form an anti-adhesion gel, which effectively prevents the surrounding tissue from being adhered after an operation as a physical barrier.

The invention provides a detection method of residual DIPEA in sulfonate hydrochloride and application thereof, the detection method comprises the following steps: (1) mixing a to-be-detected sample with a first diluent to obtain a test solution; (2) sequentially mixing a reference substance with a first diluent and a second diluent to obtain a reference substance solution; and (3) respectively carrying out gas chromatography detection on the test solution and the reference solution, and calculating the content of residual DIPEA in the to-be-detected sample according to the detection result. The detection method provided by the invention can effectively detect the content of the alkaline residual solvent DIPEA to be detected in the acidic substance sulfonate hydrochloride by utilizing the salting-out effect, and has the advantages of high specificity, high sensitivity, high precision, high accuracy, wide linear range and good solution stability.

The invention provides a synthesis method of celacarburine and a key intermediate thereof, which comprises the following steps: taking methyl 4-aminobutyrate hydrochloride as an initial raw material, and sequentially carrying out o-nitrobenzenesulfonyl protection, alkylation, amide condensation, hydrolysis and deprotection, intramolecular cyclization, removal of o-nitrobenzenesulfonyl protecting group and optional acylation reaction to obtain a target product. A synthetic route is designed through an innovative strategy, the technical bottlenecks that raw materials and reagents are difficult to obtain, steps are tedious, conditions are harsh, the yield is low and the like which commonly exist in an existing macrocyclic synthesis method are overcome, and the target product is simply and safely prepared in a high-yield mode under the mild condition. The method has the advantages of cheap and easily available raw materials and reagents, simple operation, mild conditions and no need of special equipment, has significant industrial application potential, and provides a stable and reliable material basis for subsequent pharmacological research and new drug development of celacarflurine.

The application provides a synthesis method of celacarfurine and key intermediates thereof, comprising the following steps: taking 4-amino butyric acid methyl ester hydrochloride as a starting material, sequentially performing ortho-nitrobenzenesulfonyl protection, alkylation, amide condensation, hydrolysis and deprotection, intramolecular cyclization, deprotection of ortho-nitrobenzenesulfonyl, and optional acylation to obtain a target product. The synthesis route is designed by an innovative strategy, and overcomes technical bottlenecks such as difficulty in obtaining raw materials and reagents, long steps, harsh conditions and low yield which exist in the existing macrocycle synthesis method, and the target product is prepared under mild conditions with high yield, simplicity and safety. The method is simple in operation, mild in conditions, and does not need special equipment, has significant industrial application potential, and provides a stable and reliable material basis for subsequent pharmacological research and new drug development of celacarfurine.

The invention belongs to the field of chemical synthesis, and particularly relates to a synthetic method of azetidine-2-yl (methyl) benzyl carbamate hydrochloride. According to the invention, 1-benzyl azetidine-3-alcohol is used as a basic raw material, and a series of reactions such as substitution reaction and the like are carried out to obtain the high-yield and high-purity azetidine-2-yl (methyl) benzyl carbamate hydrochloride, and the method is suitable for industrial production.

This invention provides a method for preparing (S)-2-amino-4-chlorobutyric acid alkyl ester and its salt, comprising the following steps: (1) reacting a compound of formula I with a base to generate a compound of formula II; (2) reacting a compound of formula II with a chlorinating agent to generate a dichloride; and (3) reacting the dichloride with an alcohol to generate a compound of formula III. The preparation method of this invention improves the physicochemical properties of the reaction by constructing a dimer intermediate from the intramolecular bifunctional group of the compound of formula I, then achieving hydroxyl chlorination with a chlorinating agent, and finally, under the action of an alcohol, achieving the one-pot preparation of (S)-2-amino-4-chlorobutyric acid alkyl ester hydrochloride. This method effectively reduces the amount of chlorinating agent and alcohol used, significantly improves the atom economy and effective conversion rate of the reaction, has mild reaction conditions, produces products without significant racemization, has controllable impurities, and simplifies post-processing and purification. The by-product waste salt can be recycled, making it suitable for large-scale industrial production.

The invention provides a method for detecting enantiomers of thiamphenicol glycine ester hydrochloride or thiamphenicol glycine ester hydrochloride in a preparation thereof. The method comprises the following steps: preparing a test solution: taking thiamphenicol glycine ester hydrochloride or a preparation thereof to prepare a test solution; chromatographic conditions: adopting chiral chromatography with cellulose tris-(4-chloro-3-methylphenylcarbamate) as a stationary phase and n-hexane:methanol:anhydrous ethanol:trifluoroacetic acid:ethanolamine as a mobile phase; and a determination method: taking the test solution and injecting it into a liquid chromatograph for determination.

The application discloses a trifluoromethyl benzyl ether substituted amino acid derivative, a preparation method and application thereof, and belongs to the technical field of organic compound synthesis and medicine. The synthesis method of the trifluoromethyl benzyl ether substituted amino acid derivative is obtained through two-step reaction, that is, first, a photo extension reaction is carried out between a benzyl alcohol compound and hydroxynaphthaldehyde (or hydroxybenzaldehyde), then a Schiff base is formed after an amino acid ester hydrochloride, and then the Schiff base is reduced by sodium cyanoborohydride, and then simple hydrolysis is carried out to obtain the trifluoromethyl benzyl ether substituted amino acid derivative. The preparation method has the characteristics of simple steps, mild reaction conditions and fast reaction, and meets the requirements of green chemistry. The compound prepared according to the method can selectively adjust S1P1 receptors without exciting S1P3 receptors, and is expected to be developed into a new preparation for treating idiopathic pulmonary fibrosis.

The invention provides a high performance liquid chromatography detection method of L-homoserine lactone hydrochloride, which comprises the following steps: diluting a test sample containing L-homoserine lactone hydrochloride with a diluent to obtain an L-homoserine lactone hydrochloride solution, filtering the L-homoserine lactone hydrochloride solution, and detecting the filtered L-homoserine lactone hydrochloride solution in a high performance liquid chromatograph, a CAD detector is adopted as a detector; the chromatographic column is formed by chemically bonding hydrophilic groups on organic mixed silica gel particles; the mobile phase comprises a mobile phase A and a mobile phase B, wherein the mobile phase A is acetonitrile or methanol; and the mobile phase B is an ammonium formate or ammonium acetate aqueous solution. Under the chromatographic conditions, after a base line is stable, samples are sequentially injected according to the sequence of standard sample solutions and test sample solutions with multiple gradient concentrations, standard sample solution map data and test sample map data with multiple gradient concentrations are obtained, then a standard curve of the concentration and the peak area is made, and the content of the L-homoserine test sample is calculated by combining the weighing amount of the L-homoserine test sample.

The invention relates to crystalline forms of 4-((R)-2-{[6-((S)-3-methoxy-pyrrolidin-1-yl)-2-phenyl-pyrimidine-4-carbonyl]-amino}-3-phosphono-propionyl)-piperazine-1-carboxylic acid butyl ester hydrochloride, processes for the preparation thereof, pharmaceutical compositions comprising said crystalline forms, pharmaceutical compositions prepared from such crystalline forms and their use as a medicament, especially as a P2Y12 receptor antagonist.

The invention discloses a synthesis method of (4S, 5R)-3-[2-[[fluorenylmethoxycarbonyl] amino] acetyl]-2, 2, 5-trimethyl-4-oxazolidine carboxylic acid, which comprises the following steps: S1, carrying out amino protection reaction on L-threonine methyl ester hydrochloride to form a compound I; s2, reacting the compound I with Lewis acid and a cyclization reactant to generate a compound II; s3, performing ammonolysis on the compound II to obtain a compound III; s4, carrying out hydrolysis reaction on the compound III and an alkali reagent to obtain a compound IV; and S5, reacting the compound IV with an fmoc protection reagent to obtain a final product (4S, 5R)-3-[2-[[fluorenylmethoxycarbonyl] amino] acetyl]-2, 2, 5-trimethyl-4-oxazolidine carboxylic acid. The method is high in yield and purity and low in cost.