A kind of preparation method of Decitabine
Technical field
The present invention relates to a kind of preparation method of compound, relate in particular to a kind of preparation method of cancer therapy drug Decitabine.
Background field
Decitabine (Decitabine has another name called Dezocitadine), chemical name: 4-amino-1-(2-deoxidation-β-D-erythro furans coreSugar)-1,3,5-triazines-2 (1H)-one, be the analog of 2 '-deoxycytidine, structural formula is (I):
Decitabine is a species specific DNA methylation inhibitors, and it can be by deoxycytidine kinase phosphorylation, with phosphorusThe form of hydrochlorate and DNA fusion. The Decitabine fusion of high concentration can suppress the synthetic inducing cell death of DNA, brings into play itCDCC; Cytimidine in the alternative tumour cell of Decitabine fusion of low concentration and DNA methylation transferase covalencyIn conjunction with, make DNA methylation transferase inactivation but can not cause cell death.
Decitabine is S cell cycle, specific drug phase, can induce human leukemia cell's terminal differentiation, and it is raw to reduce colonyBecome, it is mainly the deamination of cytidine deaminase at intracellular inactivation.
Decitabine is developed by SuperGen company of the U.S., within 2004, complete the III phase clinical after, SuperGen company is by the whole worldResearch, production and sales development rights transfer MGI drug company. Be approved for treatment myelosis in the U.S. in May, 2006Abnormal syndrome (MDS), now, the clinical testing that Decitabine is carried out has 29 more than, on September 24th, 2012,The declaration of Astex drugmaker, EU Committee's approval Decitabine is for newly examining primary or Secondary cases acute myeloid leukemia(AML) gerontal patient's (>=65 years old) treatment.
The Decitabine of reporting in document synthesizes the following 3 kinds of methods that mainly contain:
First method is isocyanates method, and Pliml in 1964 and Storm be the method for synthetic Decitabine the earliest, protectionAfter DRI and urea cyclization, prepare Decitabine through deprotection.
The method is used expensive isocyanic acid argentum reagent, cyclization again after glycosidation, and synthetic route is longer, and isomers divides from difficulty,Operating condition harshness.
Second method is azacitidine deoxidation method, taking azacitidine as raw material, first protects 3 ' and 5 ' hydroxyl, then de-Remove the hydroxyl of 2 ', then slough 3 ' and 5 ' hydroxyl protecting group generation Decitabine.
Cl2TiPS:1,3-bis-is chloro-1,1,3,3-tetra isopropyl disiloxane
TTMSS: three-(trimethyl silicon based) silane
ALBN: azodiisobutyronitrile
The initiation material that this route uses is azacitidine, use special reagent TiPSCh, sulfo-phenyl chloroformate andTTMSS etc., market supply is less, and cost is high, severe reaction conditions.
The third method is the direct glucosides method of 5-azepine cytimidine, and 5-azepine cytimidine and HMDS (HMDS) are anti-Should prepare two silica-based protection things. Then with the DRI direct polycondensation of protecting, then slough protecting group, isomers dividesFrom obtaining Decitabine.
This method is because of the difference of 1 leaving group A of DRI, and the difference of 3,5 hydroxy-protective groups and formingDifferent synthetic routes.
Summary of the invention
The object of the present invention is to provide one easy and simple to handle, cost is lower, and product purity is higher, has more suitability for industrialized productionThe preparation method of the Decitabine being worth.
The invention provides following technical scheme: the activation of 5-azepine cytimidine; And protection 2 '-deoxidation-D-ribose and activationThe coupling reaction of 5-azepine cytimidine and the purifying of coupled product; Deprotection; Obtain target product.
Concrete, the preparation method of Decitabine, is made up of following d-f step:
Steps d, the activation of 5-azepine cytimidine:
Under the catalysis of ammonium sulfate, the dissolving that refluxes in HMDS of 5-azepine cytimidine, obtains intermediate IV;
Step e, coupling reaction:
Under the effect of anhydrous stannic chloride, intermediate III and the reaction of intermediate IV generate the intermediate V of chirality; Intermediate VIn organic solvent, recrystallization purifying obtains V (β);
Step f, deprotection reaction:
V (β) is deprotection under organic base exists, and obtains target product Decitabine.
Further, steps d, under nitrogen protection, adds 5-azepine cytimidine in HMDS (HMDS),Then add ammonium sulfate, add hot reflux; By the time suspension becomes after clarification, then refluxes 2 hours~4 hours, and then decompression is steamedExcept HMDS, obtain the silicon ether products of amido protecting, i.e. intermediate IV; Wherein, 5-azepine cytimidine and HMDS and sulphurThe mass ratio of acid ammonium is 1:(0.5-10): (0.001-0.1);
Step e, under nitrogen protection, is dissolved in intermediate III and intermediate IV in dry chloroform, at-20 DEG C~40 DEG CThe chloroformic solution of lower dropping anhydrous stannic chloride, reaction generates the intermediate V of chirality. Feeding intake of intermediate III and intermediate IVMol ratio is (1:1.1)~(1:1.5); The molar ratio of intermediate III and anhydrous stannic chloride be (1:0.3)~(1:0.6); Reaction temperature is preferably 10 DEG C~40 DEG C, further preferably 20 DEG C~40 DEG C; Reaction time be 6 hours~14 hours; Also can pass through TCl detection reaction terminal; After having reacted, post processing way processing routinely, in obtainingMesosome V;
There are V (α) and two kinds of isomers of V (β) in intermediate V, wherein only has V (β) further to react products therefrom and beTarget product Decitabine. Intermediate V is dissolved in ethyl acetate, and activated carbon decolorizing, filters, and stirs the lower oil that dripsEther, stirring and crystallizing 6~8 hours under normal temperature, filters, appropriate petroleum ether for filter cake, drying under reduced pressure obtains V (β);Wherein, the mass volume ratio of intermediate V and ethyl acetate is (1:6)~(1:20), the matter of intermediate V and benzinumAmount volume ratio is (1:25)~(1:40);
Step f, under nitrogen protection, is dissolved in V (β) in organic base, stirring reaction, TLC detection reaction terminal.After having reacted, evaporated under reduced pressure, obtains solid, then adds the absolute methanol that is equivalent to 20~80 times of amounts of solid masses, thenAdd active carbon to reflux, after backflow 0.5-2 hour, filter, filtrate is placed to crystallization, after filtration, obtain target product Decitabine.Wherein, Washing of Filter Cake can reflux by adding in the absolute methanol that is equivalent to 20~80 times of amounts of solid masses again, backflow 0.5-2After hour, filter, filtrate is placed to crystallization, filter and merge crystal. Above-mentioned activated carbon decolorizing, filtrate crystallization, filter cake are washedWash step and can select as the case may be to repeat one or many; V (β) and organic base feed intake mass volume ratio for (1:2)~(1:20). Wherein, organic base is preferably pyridine, triethylamine, DIPEA, DMAP, the one in TMEDAOr several; More preferably pyridine.
Wherein, described intermediate III can be synthesized as follows:
Step a, methylation reaction:
In absolute methanol solution, reaction generates oxygen methylate, intermediate I to 2 '-deoxidation-D-ribose with HCl methanol solution;
Step b, the protective reaction of hydroxyl:
Under organic base exists, intermediate I and Fmoc-Cl reaction generate protection product, intermediate II:
Step c, the acylation reaction of oxygen methyl:
Under sulphuric acid catalysis, the nitration mixture reaction of intermediate II and acetic acid and aceticanhydride composition generates acylate, i.e. intermediate III;
Further, in absolute methanol solution, reaction generates oxygen methyl to step a:2 '-deoxidation-D-ribose with HCl methanol solutionChange product, i.e. intermediate I. Reaction temperature is the reflux temperature of 0 DEG C~methyl alcohol, and the reaction time is generally 30 minutes~12 littleTime; Preferable reaction temperature is normal temperature, and the reaction time is 30 minutes~6 hours. The mass fraction of HCl in HCl methanol solutionFor 0.8-1.2%. After completion of the reaction, add in the organic base of using in appropriate step b and unnecessary HCl. Reduced pressure concentration removesDesolventizing obtains the intermediate I of oily.
Step b, is dissolved in intermediate I in organic base, at-20 DEG C~40 DEG C, adds Fmoc-Cl in batches, is generally divided intoMore than two batches or two batches, charging time interval 10-30 minute; After completing, keep thermotonus of the same race, the reaction time is generalIt is 2 hours~24 hours; After having reacted, reactant liquor is poured in mixture of ice and water, rapid stirring, then adds chloroformOr the extractions such as carrene. Then obtain protecting product according to conventional disposal methods, intermediate II.
Step c, is dissolved in intermediate II in the nitration mixture reactant liquor of acetic acid and aceticanhydride composition, drips dense at-20 DEG C~10 DEG CSulfuric acid then reacts at allogeneic reaction temperature; Reaction time is 1 hour~12 hours. The wherein composition of acetic acid and aceticanhydrideFor volume ratio (10:1)~(5:1), preferably (10:1)~(8:1); Feeding intake mole of intermediate II and the concentrated sulfuric acidThan being (1:0.1)~(1:0.5), preferably (1:0.2)~(1:0.35); After having reacted, pour reactant liquor into iceIn aqueous mixtures, then add chloroform or dichloromethane extraction, regulate pH value to be with saturated sodium acid carbonate extractNeutrality, uses diatomite drainage, and filtrate layering is got organic layer and added activated carbon decolorizing, filters, and filtrate decompression is steamed and desolventized,Under residue rapid stirring, drip purified water, stirring and crystallizing, filters, and filter cake washs through ether, and decompression drying obtains class whiteLook intermediate III solid. Wherein, in prior art, intermediate III is difficult to separate from reaction system, generally through separatingAfter purification, be still viscous liquid, unrealized crystallization excessively goes out solid.
Decitabine intermediate V HPLC analytical method of the present invention
Chromatographic column: nh 2 column
Mobile phase: 0.05mol/L ammonium dihydrogen phosphate (regulating PH=3.0 with phosphoric acid): acetonitrile=(20:80)
Flow velocity: 1.0ml/min
Detect wavelength: 220nm
Sample size: 20 μ l
Column temperature: 30.0 DEG C
Need testing solution: get the about 12.5mg of Decitabine intermediate V, accurately weighed, put in 25ml measuring bottle, add purified waterUltrasonic dissolution is also diluted to scale, shakes up, and filters, and to obtain final product.
The HPLC analytical method of Decitabine is as follows:
Chromatographic condition and system suitability are filler with the octadecylsilane chemically bonded silica of improvement; With 0.03mol/LPotassium dihydrogen phosphate (regulating pH value with 4mol/L sodium hydroxide solution is 6.8) is mobile phase, and detection wavelength is 220nm,Flow velocity is 2.0ml/min, and column temperature is 15 DEG C. Get Decitabine reference substance and 2,-BrdU is each appropriate, adds methyl alcohol and dissolves alsoBe diluted in every 1ml containing Decitabine 0.5mg and 2’The mixed solution of-BrdU 0.8mg, gets 5 μ l and injects liquid chromatogramInstrument, records chromatogram, Decitabine peak and 2’The separating degree at-BrdU peak should be greater than 5.0, the theoretical plate at Decitabine peakNumber should be not less than 4500.
Determination method is got this product, adds methyl alcohol dissolving and makes the solution containing Decitabine 0.5mg in every 1ml, molten as test sampleLiquid; Precision measures 1ml and puts in 100ml measuring bottle, adds methyl alcohol and is diluted to scale, shakes up, in contrast solution. Precision measuresContrast solution 5 μ l injection liquid chromatographies, regulate detection sensitivity, and the peak height that makes principal component chromatographic peak is recorder full scale10%~20%, then precision measures need testing solution and the each 5 μ l of contrast solution, injection liquid chromatography, records look respectivelySpectrogram is to 3.5 times of main peak retention time, and in the chromatogram of need testing solution, if any impurity peaks, α-epimer peak (relativelyRetention time is 0.74) must not cross 1/2 (0.5%) of contrast solution main peak area, it is molten that other single impurity peaks must not be crossed contrast1/5 (0.2%) of liquid main peak area, total impurities must not be crossed 2 times of contrast solution main peak areas (2.0%).
The advantage of said method of the present invention is:
1, in the preparation process of intermediate III, by method for crystallising, purifying product, be conducive to the next step, Yi JijianChange the purifying of end-product.
2, in the preparation process of intermediate V, split by method for crystallising, improved the purity of product V (β),Simplify the purifying of end-product.
3, technical solution of the present invention, step is simple and easy to control, and product yield and purity are high, and production cost is low, suitable large production.
Detailed description of the invention
Now further describe beneficial effect of the present invention by following examples, be interpreted as these embodiment only for illustrationObject, do not limit the scope of the invention apparent the changing that simultaneously those of ordinary skill in the art do according to the present inventionWithin change and modification are also contained in the scope of the invention. The present invention uses but the technology and the indexing section that do not describe, isPrior art. Decompression distillation of the present invention or steaming desolventize and refer generally to vacuum is-0.06~-0.10MPa, and temperature is in phaseAnswer corresponding solvent boiling point under vacuum.
Embodiment 1: intermediate III synthetic
Under room temperature, 300g2-deoxy-D-ribose is dissolved in to 3000ml absolute methanol, system is micro-yellow transparent solution. Pass throughConstant pressure funnel drips the HCl-methanol solution of 600ml1%. Dropwise rear stirring 40 minutes. TLC detects, and reacts completeAfter, add 150ml pyridine to continue to stir 30 minutes. Suction filtration, 200ml absolute methanol washing for filter cake, merging filtrate,Then removing solvent under reduced pressure to dry, obtain 530g grease, is intermediate I.
In the there-necked flask that drying tube is housed, add homemade intermediate I 296.3g, 2000ml anhydrous pyridine, controls reaction temperatureDegree is-10 DEG C, and 10 batches of deciles add 1138gFmoc-Cl altogether, and in 10 minutes time intervals, after having added, placement room temperature is anti-Answer 6 hours. Then, add 10L frozen water under rapid stirring, have a large amount of solids to separate out in system, clarification, pours out supernatantAfter, add 3L chloroform to dissolve, then add the HCl solution of 1L10%. After stirring, separatory. Water layer is used respectively 500mlChloroform washed twice, merges organic phase, anhydrous Na2SO4Dry. Then remove solvent under reduced pressure to dry. Obtain oily liquids 1132gFor intermediate II.
Intermediate II 588g is dissolved in 2000ml acetic acid, moves into in churned mechanically there-necked flask, add 200ml secondAcid anhydrides, is cooled to after system temperature is 0 DEG C and drips the 25ml concentrated sulfuric acid with cryosel bath. After dropwising, 15 DEG C of maintenance systems are anti-Answer 5 hours. Then reactant liquor is poured in 10L frozen water mixed liquor, solid is separated out, and clarification, pours out after supernatant, adds3L chloroform stirring and dissolving solid, uses NaHCO3It is 7.2 that saturated aqueous solution is neutralized to pH. Then use diatomite drainage, filtrateLayering, organic phase adds 50g active carbon room temperature to stir decolouring in 30 minutes, filter activity charcoal, filtrate decompression is steamed and is desolventized, surplusUnder excess stirs, drip purified water 6L, stirring and crystallizing 6 hours, filters, ether washing, and decompression drying, obtains 540g classWhite intermediate III solid.
Synthesizing of embodiment 2 Decitabines
Under nitrogen protection, 500g5-azepine cytimidine is added in 4000mlHMDS, add 12.5g sulfate of ammoniac as catalysisAgent, under stirring, back flow reaction to solution becomes clarification, then refluxes 2 hours, then removes HMDS under reduced pressure to the greatest extent, obtainsFaint yellow grease intermediate IV.
Under nitrogen protection, intermediate III 370g and intermediate IV 220g are dissolved in 3000ml chloroform, will be anti-under mechanical agitationThe system of answering keeps 10 DEG C, drips the anhydrous SnCl of 35ml4The solution of 200ml chloroform. In dropping process reactant color gradually byYellow adds and is deep to brown. After insulation reaction 8 hours, by the 5L chloroform of its impouring, then add the saturated NaHCO of 5L3The aqueous solution, stirs 20 minutes. Mixture is crossed diatomite short column, separatory, and organic phase, after removing solvent under reduced pressure, obtains oily liquidBody; This grease is dissolved in and is dissolved in 2L ethyl acetate, add 30g active carbon, stirring at room temperature 30 minutes, decolouring,Filter, filtrate is stirred the lower 10L of dropping benzinum, and stirring and crystallizing 6 hours under normal temperature, filters appropriate benzinum for filter cakeWashing, drying under reduced pressure, obtains V (β); It is 98.2% that HPLC detects purity.
Gained intermediate V (β) is dissolved in 1000ml triethylamine, stirs lower room temperature reaction, TLC detects, and reacts completelyAfter, evaporated under reduced pressure, then adds 6780ml absolute methanol, and 30g active carbon, adds hot reflux 2 hours, filters filtrateAirtight placement crystallization, adds 6780ml absolute methanol to add hot reflux in filter cake, and 0.5 hour, to filter, the airtight placement of filtrate is analysedBrilliant. Suction filtration, merges the crystal of 2 crystallizatioies. 40 DEG C of vacuum drying, obtain white products. 1920ml will be added in white productsAbsolute methanol, and 5g active carbon, add hot reflux 1 hour, filters the airtight placement crystallization of filtrate, suction filtration, washing, 40 DEG CVacuum drying, obtains white products, is Decitabine after testing, and yield is that 37.0%, HPLC detection purity is 99.6%.
Synthesizing of embodiment 3 Decitabines
Under nitrogen protection, 500g5-azepine cytimidine is added in 3000mlHMDS, adds 5g sulfate of ammoniac as catalyst,Under stirring, back flow reaction to solution becomes clarification, then refluxes 2 hours, then removes HMDS under reduced pressure to the greatest extent, obtains yellowishLook grease intermediate IV.
Under nitrogen protection, intermediate III 370g and intermediate IV 180g are dissolved in 3000ml chloroform, will be anti-under mechanical agitationThe system of answering keeps 10 DEG C to drip the anhydrous SnCl of 25ml4The solution of 200ml chloroform. In dropping process, reactant color is gradually by HuangLook adds and is deep to brown. After insulation reaction 8 hours, by the 5L chloroform of its impouring, then add the saturated NaHCO of 5L3The aqueous solution, stirs 20 minutes. Mixture is crossed diatomite short column, separatory, and organic phase, after removing solvent under reduced pressure, obtains oily liquidBody; This grease is dissolved in and is dissolved in 2L ethyl acetate, add 25g active carbon, stirring at room temperature 30 minutes, decolouring,Filter, filtrate is stirred the lower 1L of dropping benzinum, and stirring and crystallizing 6 hours under normal temperature, filters, and filter cake is washed with appropriate benzinumWash, drying under reduced pressure, obtains V (β); It is 98.2% that HPLC detects purity.
Gained intermediate V (β) is dissolved in 1000ml pyridine, stirs lower room temperature reaction, TLC detects, after reacting completely,Evaporated under reduced pressure, then adds 7L absolute methanol, and 20g active carbon, adds hot reflux 1 hour, filters the airtight placement of filtrateCrystallization, adds 5L absolute methanol to add hot reflux in filter cake, 0.5 hour, filter the airtight placement crystallization of filtrate. 40 DEG C of vacuumDry, obtain white products. Be Decitabine after testing, yield is that 37.6%, HPLC detection purity is 99.7%.
Synthesizing of embodiment 4 Decitabines
Under nitrogen protection, 500g5-azepine cytimidine is added in 5000mlHMDS, adds 25g sulfate of ammoniac as catalyst,Under stirring, back flow reaction to solution becomes clarification, then refluxes 2 hours, then removes HMDS under reduced pressure to the greatest extent, obtains yellowishLook grease intermediate IV.
Under nitrogen protection, intermediate III 370g and intermediate IV 190g are dissolved in 3000ml chloroform, will be anti-under mechanical agitationThe system of answering keeps 10 DEG C to drip the anhydrous SnCl of 30ml4The solution of 200ml chloroform. In dropping process, reactant color is gradually by HuangLook adds and is deep to brown. After insulation reaction 10 hours, by the 5L chloroform of its impouring, then add the saturated NaHCO of 5L3The aqueous solution, stirs 20 minutes. Mixture is crossed diatomite short column, separatory, and organic phase, after removing solvent under reduced pressure, obtains oily liquidBody; This grease is dissolved in and is dissolved in 2.5L ethyl acetate, add 25g active carbon, stirring at room temperature 30 minutes, decolouring,Filter, filtrate is stirred the lower 5L of dropping benzinum, and stirring and crystallizing 7 hours under normal temperature, filters, and filter cake is washed with appropriate benzinumWash, drying under reduced pressure, obtains V (β); It is 98.2% that HPLC detects purity.
Gained intermediate V (β) is dissolved in 1200mlDIPEA, stirs lower room temperature reaction, TLC detects, and reacts completelyAfter, evaporated under reduced pressure, then adds 9L absolute methanol, and 25g active carbon, adds hot reflux 2 hours, filters, and filtrate is airtightPlace crystallization, in filter cake, add 5ml absolute methanol to add hot reflux, 0.5 hour, filter the airtight placement crystallization of filtrate. Suction filtration,Filter cake, through 40 DEG C of vacuum drying, obtains white products, is Decitabine after testing, and yield is that 36.8%, HPLC detection is pureDegree is 99.5%.
Synthesizing of embodiment 5 Decitabines
Under nitrogen protection, 500g5-azepine cytimidine is added in 2500mlHMDS, adds 2.5g sulfate of ammoniac as catalyst,Under stirring, back flow reaction to solution becomes clarification, then refluxes 2 hours, then removes HMDS under reduced pressure to the greatest extent, obtains yellowishLook grease intermediate IV.
Under nitrogen protection, intermediate III 370g and intermediate IV 200g are dissolved in 3000ml chloroform, will be anti-under mechanical agitationThe system of answering keeps 10 DEG C to drip the anhydrous SnCl of 35ml4The solution of 200ml chloroform. In dropping process, reactant color is gradually by HuangLook adds and is deep to brown. After insulation reaction 12 hours, by the 5L chloroform of its impouring, then add the saturated NaHCO of 5L3The aqueous solution, stirs 20 minutes. Mixture is crossed diatomite short column, separatory, and organic phase, after removing solvent under reduced pressure, obtains oily liquidBody; This grease is dissolved in and is dissolved in 1.5L ethyl acetate, add 30g active carbon, stirring at room temperature 30 minutes, decolouring,Filter, filtrate is stirred the lower 6L of dropping benzinum, and stirring and crystallizing 6~8 hours under normal temperature, filters appropriate oil for filter cakeEther washing, drying under reduced pressure, obtains V (β); It is 98.2% that HPLC detects purity.
Gained intermediate V (β) is dissolved in 1500mlDMAP, stirs lower room temperature reaction, TLC detects, and reacts completelyAfter, evaporated under reduced pressure, then adds 4520ml absolute methanol, and 25g active carbon, adds hot reflux 2 hours, filters filtrateAirtight placement crystallization, adds 4520ml absolute methanol to add hot reflux in filter cake, and 0.5 hour, to filter, the airtight placement of filtrate is analysedBrilliant. Suction filtration, merges the crystal of 2 crystallizatioies, then adds 1920ml absolute methanol, and 5g active carbon, adds hot reflux0.5 hour, filter, the airtight placement crystallization of filtrate, suction filtration, washing, 40 DEG C of vacuum drying, obtain white products, after testingFor Decitabine, yield is that 37.3%, HPLC detection purity is 99.3%.
Synthesizing of embodiment 6 Decitabines
Under nitrogen protection, 500g5-azepine cytimidine is added in 3500mlHMDS, add 37.5g sulfate of ammoniac as catalysisAgent, under stirring, back flow reaction to solution becomes clarification, then refluxes 2 hours, then removes HMDS under reduced pressure to the greatest extent, obtainsFaint yellow grease intermediate IV.
Under nitrogen protection, intermediate III 370g and intermediate IV 170g are dissolved in 3000ml chloroform, will be anti-under mechanical agitationThe system of answering keeps 10 DEG C to drip the anhydrous SnCl of 40ml4The solution of 200ml chloroform. In dropping process, reactant color is gradually by HuangLook adds and is deep to brown. After insulation reaction 14 hours, by the 5L chloroform of its impouring, then add the saturated NaHCO of 5L3The aqueous solution, stirs 20 minutes. Mixture is crossed diatomite short column, separatory, and organic phase, after removing solvent under reduced pressure, obtains oily liquidBody; This grease is dissolved in and is dissolved in 1.3L ethyl acetate, add 15g active carbon, stirring at room temperature 30 minutes, decolouring,Filter, filtrate is stirred the lower 8L of dropping benzinum, and stirring and crystallizing 8 hours under normal temperature, filters, and filter cake is washed with appropriate benzinumWash, drying under reduced pressure, obtains V (β); It is 98.2% that HPLC detects purity.
Gained intermediate V (β) is dissolved in 1000ml triethylamine, stirs lower room temperature reaction, TLC detects, and reacts completelyAfter, evaporated under reduced pressure, then adds 5650ml absolute methanol, and 12g active carbon, adds hot reflux 0.5 hour, filters filterThe liquid-tight placement crystallization that closes, adds 5650ml absolute methanol to add hot reflux in filter cake, and 0.5 hour, filter, filter cake is true through 40 DEG CEmpty dry, obtain white products, be Decitabine after testing, yield is that 37.1%, HPLC detection purity is 99.2%.