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Synthetic method for 2-chloro-4-amino-6,7-dimethoxy quinazoline
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A technology of dimethoxyquinazoline and synthesis method, which is applied in the synthesis field of 2-chloro-4-amino-6,7-dimethoxyquinazoline, can solve the problem of insufficient reaction of reactants and target product Instability, complex synthesis method and other problems, to achieve the effect of complete reaction, stable yield and simplified reaction steps
Inactive Publication Date: 2017-09-01
浙江逸都生物科技有限公司
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[0003] The synthesis method of 2-chloro-4-amino-6,7-dimethoxyquinazoline in the prior art is relatively complicated, and the reaction of the reactants is not sufficient, which easily causes waste of raw materials, and the obtained target product is unstable
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[0037] The synthetic method of 2-chloro-4-amino-6,7-dimethoxyquinazoline of the present invention comprises the steps:
[0038] 1) Preparation of 3,4-dimethoxyphenyl isocyanate
[0039] (1) First dissolve 3,4-dimethoxyaniline and dichloroethane and then heat to generate 3,4-dimethoxyaniline solution, the quality of 3,4-dimethoxyaniline and dichloroethane The ratio is 3:10, mixing in this ratio can improve the reaction efficiency of 3,4-dimethoxyaniline and dichloroethane, make the reaction of reactants more thorough, and reduce the waste of raw materials;
[0040] (2) Then add triphosgene and dichloroethane into the first reaction flask, stir and dissolve, lower the temperature to within 10°C, add 3,4-dimethoxyaniline solution dropwise into the first reaction flask, ~ 2 hours to finish dripping;
[0041] (3) heating and refluxing for 3h, reclaiming ethylene dichloride to obtain 3,4-dimethoxyphenyl isocyanate;
[0042] 2) Preparation of 3,4-dimethoxyphenylcyanuria
[0043] ...
Embodiment 1
[0060] 1) Preparation of 3,4-dimethoxyphenyl isocyanate
[0061] (1) At first 124g of 3,4-dimethoxyaniline and 400ml of ethylene dichloride were dissolved and then heated to generate 3,4-dimethoxyaniline solution;
[0062] (2) Then add triphosgene and 400ml of dichloroethane into the first reaction flask, stir and dissolve, lower the temperature to within 10°C, add the 3,4-dimethoxyaniline solution dropwise into the first reaction flask, Finish dripping within 1 to 2 hours;
[0063] (3) warming up and refluxing for 3h, reclaiming ethylene dichloride to obtain 3,4-dimethoxyphenyl isocyanate with a yield of 0.94;
[0064] 2) Preparation of 3,4-dimethoxyphenylcyanuria
[0065] (1) at first concentration is that 50% cyanamide 150g and concentration are 50% lye 200g to add in the second reaction bottle, reduce temperature to within 3 ℃;
[0066] (2) Add 3,4-dimethoxyphenyl isocyanate dropwise to the second reaction flask, and raise the temperature to 30° C. after the dropwise ad...
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Abstract
The invention discloses a synthetic method for 2-chloro-4-amino-6,7-dimethoxy quinazoline. The synthetic method comprises the following steps: 1) preparing 3,4-dimethoxyphenyl isocyanate; 2) preparing 3,4-dimethoxyphenyl cyanourea; 3) preparing a 2-chloro-4-amino-6,7-dimethoxy quinazoline crude product; and 4) preparing a 2-chloro-4-amino-6,7-dimethoxy quinazoline fine product. The synthetic method disclosed by the invention simplifies reaction steps and increases the product yield; reaction conditions are optimized, so that reactants react more sufficiently, and therefore, generation of byproducts is reduced, production efficiency is improved, reactants are prevented from being oxidized, reaction is more complete, the target object can be obtained by direct filtering and drying during post-treatment, and the yield is stable.
Description
technical field [0001] The invention relates to a synthesis method of 2-chloro-4-amino-6,7-dimethoxyquinazoline. Background technique [0002] 2-Chloro-4-amino-6,7-dimethoxyquinazoline is an important intermediate for the synthesis of prazosin hydrochloride, terazosin hydrochloride, alfuzosinhydrochloride, doxazosin mesylate and other drugs body. This class of drugs is selective epinephrine alfa 1 —Receptor blockers, which can reduce peripheralvascular resistance, and have lowering effects on systolic and diastolic blood pressure; have the effect of relaxing bladder and prostatesmooth muscle, and can relieve symptoms of dysuria caused by prostatic hypertrophy. [0003] The synthesis method of 2-chloro-4-amino-6,7-dimethoxyquinazoline in the prior art is relatively complicated, and the reaction of the reactants is not sufficient, which easily causes waste of raw materials, and the obtained target product is unstable . Contents of the invention [0004] The object of ...
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