Technical field
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The present invention relates to theophylline synthesis technical field, particularly relate to a kind of synthetic method of theophylline.
Background technology
Theophylline is 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-diketone, and can be described as again dioxy dimethylpurine, 1,3-dimethyl xanthine, 1,3-dimethyl xanthine etc., outward appearance is white crystals or crystalline powder, odorless, bitter, and its molecular formula is C 7h 8n 4o 2, molecular weight is 180.16, No. CAS is 58-55-9, and density is 1.62g/cm 3, fusing point is 270-274 DEG C, dissolved in water (1:120), ethanol (1:18), chloroform (1:86), hydroxide alkali lye, ammoniacal liquor, dilute hydrochloric acid and dust technology, is slightly soluble in ether.It is methyl purine class medicine, has cardiac stimulant, diuresis, coronary artery dilator, excited maincenter through effects such as systems, can be used for treating bronchial asthma, pulmonary emphysema, bronchitis, cardiac dyspnea.Its structural formula is:
Current theophylline preparation method mainly contains biological extraction method and chemical synthesis two kinds.Wherein biological extraction method take mainly tealeaves as raw material, wait until theophylline, but the purity of theophylline is not high by steps such as extraction, resin absorption, purifying.And chemical synthesis major part is by following two kinds of approach preparation: one is employing 1,3-dimethyl-4-amino-5-formamido-uracil and sodium hydroxide solution react at 90-95 DEG C, obtained theophylline crude product, obtain finished product, but the yield of theophylline is low through hot water recrystallization, activated carbon decolorizing; Two be with ethyl cyanoacetate and dimethyl urea for raw material, obtain crude product through condensation, nitrosification, reduction, formylation, ring-closure reaction, then recrystallization and obtaining, but cumbersome, and the yield of each step reaction is low.
Summary of the invention
The technical problem that basic background technology exists, the present invention proposes a kind of synthetic method of theophylline, and the theophylline purity adopting chemical synthesis to obtain is higher, and raw material is cheaply easy to get, and preparation cost is low, and preparation technology is simple, and comprehensive yield is high.
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, amino-1, the 3-FU dimethyl of preparation 6-: methyl-sulfate, 6-Urea,amino-pyrimidine, sodium hydroxide solution and water are added in the first reaction vessel, after 4-5h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl;
S2, preparation 5-nitroso-group-6-amino-1,3-FU dimethyl: by S1 gained 6-amino-1, after 3-FU dimethyl, acetic acid and water add and mix in the second reaction vessel, be warming up to 78-82 DEG C, then drip sodium nitrite in aqueous solution, insulation 28-32min, do not stop in insulating process to stir, then be cooled to after 10-14h is stirred in 0-2 DEG C of continuation and filter, the cleaning of filter cake cold water, drying are obtained amino-1, the 3-FU dimethyl of 5-nitroso-group-6-;
S3, prepare theophylline: in hydrogen autoclave, add S2 gained 5-nitroso-group-6-amino-1,3-FU dimethyl, palladium-carbon catalyst and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 2.5-3.5MPa, after maintaining pressure 3-4h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 33-37 DEG C, again brown oil is dissolved in acton, after being heated to 97-100 DEG C, insulation 3.5-4.5h, obtains theophylline through underpressure distillation.
Wherein, the cold water in S2 refers to that temperature is the distilled water of 1-2 DEG C, and the acton in S3 can be called triethyl orthoformate again.
Preferably, in S1, concentration of sodium hydroxide solution is 30-35wt%, and the volume ratio of sodium hydroxide solution and water is 5-8:24-28.
Preferably, in S1, the mol ratio of methyl-sulfate and 6-Urea,amino-pyrimidine is the mass volume ratio (g/ml) of 2:1,6-Urea,amino-pyrimidine and sodium hydroxide solution is 3-6:5-8.
Preferably, in S1, be that the sodium hydroxide solution of 31-33wt% and water add in the first reaction vessel by 2 parts of methyl-sulfates, 1 part of 6-Urea,amino-pyrimidine, concentration by molar part, after 4.3-4.7h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl, wherein the mass volume ratio (g/ml) of 6-Urea,amino-pyrimidine and sodium hydroxide solution is 4-5:6-7, and the volume ratio of sodium hydroxide solution and water is 6-7:25-27.
Methyl-sulfate in above-mentioned S1 and 6-Urea,amino-pyrimidine mol ratio theoretical value in methyl reaction is 2:1, namely should be 2:1 according to the mol ratio of reaction mechanism release methyl-sulfate and 6-Urea,amino-pyrimidine; But in actual production process, often add into methyl-sulfate, make mol ratio be greater than 2:1, thus make 6-Urea,amino-pyrimidine react complete as far as possible, improve yield, as described in Example 7.
Preferably, in S2, the mass volume ratio (g/ml) of amino-1, the 3-FU dimethyl of 6-and acetic acid is 0.8-1.2:8-12, and the volume ratio of acetic acid and water is 0.8-1.2:0.8-1.2.
Preferably, in S2, the volume ratio of sodium nitrite in aqueous solution and acetic acid is 1.5-2.5:4-6, and the concentration of sodium nitrite in aqueous solution is 2-4mol/L, and the rate of addition of sodium nitrite in aqueous solution is 18-22ml/h.
Preferably, in S2, by S1 gained 6-amino-1, 3-FU dimethyl, after acetic acid and water add and mix in the second reaction vessel, be warming up to 79-81 DEG C, then drip with the rate of addition of 19-21ml/h the sodium nitrite in aqueous solution that concentration is 2.5-3.5mol/L, insulation 29-31min, do not stop in insulating process to stir, then be cooled to after 11-13h is stirred in 0-1 DEG C of continuation and filter, filter cake cold water is cleaned, drying obtains 5-nitroso-group-6-amino-1, 3-FU dimethyl, wherein 6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and acetic acid is 0.9-1.1:9-11, the volume ratio of acetic acid and water is 0.9-1.1:0.9-1.1, the volume ratio of sodium nitrite in aqueous solution and acetic acid is 1.8-2.2:4.5-5.5.
Preferably, in S3,5-nitroso-group-6-amino-1, the mass ratio of 3-FU dimethyl and palladium-carbon catalyst is -:97-103, palladium content in palladium carbon catalyzer is 9.8-10.2wt%, the mass volume ratio (g/ml) of amino-1, the 3-FU dimethyl of 5-nitroso-group-6-and methyl alcohol is 2-3:28-32.
Preferably, in S3, the volume ratio of methyl alcohol and acton is 2-4:4.5-5.5.
Preferably, in S3, - part S2 gained 5-nitroso-group-6-amino-1 is added by weight in hydrogen autoclave, 3-FU dimethyl, 99-101 part palladium-carbon catalyst and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 2.8-3.2MPa, after maintaining pressure 3.3-3.7h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 34-36 DEG C, again brown oil is dissolved in acton, after being heated to 99-100 DEG C, insulation 3.7-4.3h, theophylline is obtained through underpressure distillation, wherein palladium content in palladium carbon catalyzer is 10wt%, 5-nitroso-group-6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and methyl alcohol is 2.4-2.6:29-31, the volume ratio of methyl alcohol and acton is 2.5-3.5:4.8-5.2.
In the present invention, theophylline synthetic route is as follows:
The present invention is relative to prior art, adopt chemical synthesis can obtain the higher theophylline of purity, and adopt methyl-sulfate, 6-Urea,amino-pyrimidine as starting raw material, simple and easy to get, and palladium-carbon catalyst can promote quick and high efficient reaction to carry out, make energy-conserving and environment-protective of the present invention, also greatly reduce by the preparation cost invented, adopt method such as cryosel bath stirring, hydrogen high pressure, rotary evaporation etc. combined simultaneously, not only make synthesis technique of the present invention simple, and comprehensive yield is higher than the yield of other synthesis techniques, be suitable for industrial production.
Embodiment
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, amino-1, the 3-FU dimethyl of preparation 6-: methyl-sulfate, 6-Urea,amino-pyrimidine, sodium hydroxide solution and water are added in the first reaction vessel, after 4-5h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl;
S2, preparation 5-nitroso-group-6-amino-1,3-FU dimethyl: by S1 gained 6-amino-1, after 3-FU dimethyl, acetic acid and water add and mix in the second reaction vessel, be warming up to 78-82 DEG C, then drip sodium nitrite in aqueous solution, insulation 28-32min, do not stop in insulating process to stir, then be cooled to after 10-14h is stirred in 0-2 DEG C of continuation and filter, the cleaning of filter cake cold water, drying are obtained amino-1, the 3-FU dimethyl of 5-nitroso-group-6-;
S3, prepare theophylline: in hydrogen autoclave, add S2 gained 5-nitroso-group-6-amino-1,3-FU dimethyl, palladium-carbon catalyst and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 2.5-3.5MPa, after maintaining pressure 3-4h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 33-37 DEG C, again brown oil is dissolved in acton, after being heated to 97-100 DEG C, insulation 3.5-4.5h, obtains theophylline through underpressure distillation.
Below, by specific embodiment, technical scheme of the present invention is described in detail.
Embodiment 1
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
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S1, amino-1, the 3-FU dimethyl of preparation 6-: methyl-sulfate, 6-Urea,amino-pyrimidine, sodium hydroxide solution and water are added in the first reaction vessel, after 4h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl;
S2, preparation 5-nitroso-group-6-amino-1,3-FU dimethyl: by S1 gained 6-amino-1, after 3-FU dimethyl, acetic acid and water add and mix in the second reaction vessel, be warming up to 82 DEG C, then drip sodium nitrite in aqueous solution, insulation 28min, do not stop in insulating process to stir, then be cooled to after 10h is stirred in 2 DEG C of continuation and filter, the cleaning of filter cake cold water, drying are obtained amino-1, the 3-FU dimethyl of 5-nitroso-group-6-;
S3, prepare theophylline: in hydrogen autoclave, add S2 gained 5-nitroso-group-6-amino-1,3-FU dimethyl, palladium-carbon catalyst and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 3.5MPa, after maintaining pressure 3h, utilizes diatomite filtration to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 37 DEG C, then brown oil is dissolved in acton, after being heated to 97 DEG C, insulation 4.5h, obtains theophylline through underpressure distillation.
Embodiment 2
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, amino-1, the 3-FU dimethyl of preparation 6-: methyl-sulfate, 6-Urea,amino-pyrimidine, sodium hydroxide solution and water are added in the first reaction vessel, after 5h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl;
S2, preparation 5-nitroso-group-6-amino-1,3-FU dimethyl: by S1 gained 6-amino-1, after 3-FU dimethyl, acetic acid and water add and mix in the second reaction vessel, be warming up to 78 DEG C, then drip sodium nitrite in aqueous solution, insulation 32min, do not stop in insulating process to stir, then be cooled to after 14h is stirred in 0 DEG C of continuation and filter, the cleaning of filter cake cold water, drying are obtained amino-1, the 3-FU dimethyl of 5-nitroso-group-6-;
S3, prepare theophylline: in hydrogen autoclave, add S2 gained 5-nitroso-group-6-amino-1,3-FU dimethyl, palladium-carbon catalyst and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 2.5MPa, after maintaining pressure 4h, utilizes diatomite filtration to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 33 DEG C, then brown oil is dissolved in acton, after being heated to 100 DEG C, insulation 3.5h, obtains theophylline through underpressure distillation.
Embodiment 3
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, preparation 6-amino-1,3-FU dimethyl: be that the sodium hydroxide solution of 31wt% and water add in the first reaction vessel by 2 parts of methyl-sulfates, 1 part of 6-Urea,amino-pyrimidine, concentration by molar part, after 4.7h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl, wherein the mass volume ratio (g/ml) of 6-Urea,amino-pyrimidine and sodium hydroxide solution is 4:7, and the volume ratio of sodium hydroxide solution and water is 6:27;
S2, preparation 5-nitroso-group-6-amino-1, 3-FU dimethyl: by S1 gained 6-amino-1, 3-FU dimethyl, after acetic acid and water add and mix in the second reaction vessel, be warming up to 79 DEG C, then drip with the rate of addition of 21ml/h the sodium nitrite in aqueous solution that concentration is 2.5mol/L, insulation 31min, do not stop in insulating process to stir, then be cooled to after 13h is stirred in 0 DEG C of continuation and filter, filter cake cold water is cleaned, drying obtains 5-nitroso-group-6-amino-1, 3-FU dimethyl, wherein 6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and acetic acid is 0.9:11, the volume ratio of acetic acid and water is 0.9:1.1, the volume ratio of sodium nitrite in aqueous solution and acetic acid is 1.8:5.5,
S3, prepare theophylline: in hydrogen autoclave, add parts of S2 gained 5-nitroso-group-6-amino-1 by weight, 3-FU dimethyl, 101 parts of palladium-carbon catalysts and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 2.8MPa, after maintaining pressure 3.7h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 34 DEG C, again brown oil is dissolved in acton, after being heated to 100 DEG C, insulation 3.7h, theophylline is obtained through underpressure distillation, wherein palladium content in palladium carbon catalyzer is 10wt%, 5-nitroso-group-6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and methyl alcohol is 2.6:29, the volume ratio of methyl alcohol and acton is 3.5:4.8.
Embodiment 4
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, preparation 6-amino-1,3-FU dimethyl: be that the sodium hydroxide solution of 33wt% and water add in the first reaction vessel by 2 parts of methyl-sulfates, 1 part of 6-Urea,amino-pyrimidine, concentration by molar part, after 4.3h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl, wherein the mass volume ratio (g/ml) of 6-Urea,amino-pyrimidine and sodium hydroxide solution is 5:6, and the volume ratio of sodium hydroxide solution and water is 7:25;
S2, preparation 5-nitroso-group-6-amino-1, 3-FU dimethyl: by S1 gained 6-amino-1, 3-FU dimethyl, after acetic acid and water add and mix in the second reaction vessel, be warming up to 81 DEG C, then drip with the rate of addition of 19ml/h the sodium nitrite in aqueous solution that concentration is 3.5mol/L, insulation 29min, do not stop in insulating process to stir, then be cooled to after 11h is stirred in 1 DEG C of continuation and filter, filter cake cold water is cleaned, drying obtains 5-nitroso-group-6-amino-1, 3-FU dimethyl, wherein 6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and acetic acid is 1.1:9, the volume ratio of acetic acid and water is 1.1:0.9, the volume ratio of sodium nitrite in aqueous solution and acetic acid is 2.2:4.5,
S3, prepare theophylline: in hydrogen autoclave, add parts of S2 gained 5-nitroso-group-6-amino-1 by weight, 3-FU dimethyl, 99 parts of palladium-carbon catalysts and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 3.2MPa, after maintaining pressure 3.3h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 36 DEG C, again brown oil is dissolved in acton, after being heated to 99 DEG C, insulation 4.3h, theophylline is obtained through underpressure distillation, wherein palladium content in palladium carbon catalyzer is 10wt%, 5-nitroso-group-6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and methyl alcohol is 2.4:31, the volume ratio of methyl alcohol and acton is 2.5:5.2.
Embodiment 5
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, preparation 6-amino-1,3-FU dimethyl: be that the sodium hydroxide solution of 30wt% and water add in the first reaction vessel by 2 parts of methyl-sulfates, 1 part of 6-Urea,amino-pyrimidine, concentration by molar part, after 4.5h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl, wherein the mass volume ratio (g/ml) of 6-Urea,amino-pyrimidine and sodium hydroxide solution is 6:5, and the volume ratio of sodium hydroxide solution and water is 1:3;
S2, preparation 5-nitroso-group-6-amino-1, 3-FU dimethyl: by S1 gained 6-amino-1, 3-FU dimethyl, after acetic acid and water add and mix in the second reaction vessel, be warming up to 80 DEG C, then drip with the rate of addition of 22ml/h the sodium nitrite in aqueous solution that concentration is 2mol/L, insulation 30min, do not stop in insulating process to stir, then be cooled to after 12h is stirred in 0 DEG C of continuation and filter, filter cake cold water is cleaned, drying obtains 5-nitroso-group-6-amino-1, 3-FU dimethyl, wherein 6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and acetic acid is 0.3:2, the volume ratio of acetic acid and water is 3:2, the volume ratio of sodium nitrite in aqueous solution and acetic acid is 2.5:4,
S3, prepare theophylline: in hydrogen autoclave, add parts of S2 gained 5-nitroso-group-6-amino-1 by weight, 3-FU dimethyl, 97 parts of palladium-carbon catalysts and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 3MPa, after maintaining pressure 3.5h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 35 DEG C, again brown oil is dissolved in acton, after being heated to 100 DEG C, insulation 4h, theophylline is obtained through underpressure distillation, wherein palladium content in palladium carbon catalyzer is 10.2wt%, 5-nitroso-group-6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and methyl alcohol is 1:16, the volume ratio of methyl alcohol and acton is 2:5.5.
Embodiment 6
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, preparation 6-amino-1,3-FU dimethyl: be that the sodium hydroxide solution of 35wt% and water add in the first reaction vessel by 2 parts of methyl-sulfates, 1 part of 6-Urea,amino-pyrimidine, concentration by molar part, after 4.5h is stirred in cryosel bath, filtration, washing, drying obtain 6-amino-1,3-FU dimethyl, wherein the mass volume ratio (g/ml) of 6-Urea,amino-pyrimidine and sodium hydroxide solution is 3:8, and the volume ratio of sodium hydroxide solution and water is 5:28;
S2, preparation 5-nitroso-group-6-amino-1, 3-FU dimethyl: by S1 gained 6-amino-1, 3-FU dimethyl, after acetic acid and water add and mix in the second reaction vessel, be warming up to 80 DEG C, then drip with the rate of addition of 18ml/h the sodium nitrite in aqueous solution that concentration is 4mol/L, insulation 30min, do not stop in insulating process to stir, then be cooled to after 12h is stirred in 0 DEG C of continuation and filter, filter cake cold water is cleaned, drying obtains 5-nitroso-group-6-amino-1, 3-FU dimethyl, wherein 6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and acetic acid is 0.2:3, the volume ratio of acetic acid and water is 2:3, the volume ratio of sodium nitrite in aqueous solution and acetic acid is 1:4,
S3, prepare theophylline: in hydrogen autoclave, add parts of S2 gained 5-nitroso-group-6-amino-1 by weight, 3-FU dimethyl, 103 parts of palladium-carbon catalysts and methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 3MPa, after maintaining pressure 3.5h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 35 DEG C, again brown oil is dissolved in acton, after being heated to 100 DEG C, insulation 4h, theophylline is obtained through underpressure distillation, wherein palladium content in palladium carbon catalyzer is 9.8wt%, 5-nitroso-group-6-amino-1, the mass volume ratio (g/ml) of 3-FU dimethyl and methyl alcohol is 3:28, the volume ratio of methyl alcohol and acton is 4:4.5.
Embodiment 7
The synthetic method of a kind of theophylline that the present invention proposes, comprises the steps:
S1, preparation 6-amino-1,3-FU dimethyl: be that sodium hydroxide solution and the 52ml water of 32wt% adds in the first reaction vessel by 158.6mmol methyl-sulfate (20g), 67.2mmol6-Urea,amino-pyrimidine (8.6g), 12.6ml concentration, after 4.5h is stirred in cryosel bath, filtration, washing, drying obtain amino-1, the 3-FU dimethyl of 7.14g 6-;
S2, preparation 5-nitroso-group-6-amino-1,3-FU dimethyl: by 5g S1 gained 6-amino-1, after 3-FU dimethyl, 50ml acetic acid and 50ml water add and mix in the second reaction vessel, be warming up to 80 DEG C, then drip with the rate of addition of 20ml/h the sodium nitrite in aqueous solution that 20ml concentration is 3.1mol/L, insulation 30min, do not stop in insulating process to stir, then be cooled to after 12h is stirred in 0 DEG C of continuation and filter, the cleaning of filter cake cold water, drying are obtained amino-1, the 3-FU dimethyl of 4.19g 5-nitroso-group-6-;
S3, prepare theophylline: in hydrogen autoclave, add 2.55g S2 gained 5-nitroso-group-6-amino-1, 3-FU dimethyl, 100mg palladium-carbon catalyst and 30ml methyl alcohol, passing into hydrogen makes the pressure in hydrogen autoclave be 3MPa, after maintaining pressure 3.5h, diatomite filtration is utilized to obtain filtrate, filtrate rotary evaporation is obtained brown oil, the temperature of rotary evaporation is 35 DEG C, again brown oil is dissolved in 50ml acton, after being heated to 100 DEG C, insulation 4h, 1.42g theophylline is obtained through underpressure distillation, wherein palladium content in palladium carbon catalyzer is 10wt%.
Embodiment 1 and embodiment 2 do not provide proportioning raw materials situation, and namely raw material can react by arbitrary proportion, because ratio change does not affect the carrying out of reaction usually, just can have influence on the height of yield.
Amino-1, the 3-FU dimethyl of obtained 7.14g 6-in the S1 of embodiment 7, yield is 68.6%; Amino-1, the 3-FU dimethyl of obtained 4.19g 5-nitroso-group-6-in S2, yield is 71.3%; Obtained 1.42g theophylline in S3, yield is 78.2%.
The above; be only the present invention's preferably embodiment; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, all should be encompassed within protection scope of the present invention.
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