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Method for preparing Ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate

The technology of ethyl norfoxamate and ethyl acetoacetate is applied in the field of preparation of ethyl norfoxamate, can solve the problems of long production cycle, troublesome post-processing, many unit operations, etc., and achieves low production cost and simple post-processing. , The effect of simplifying the operation process

Inactive Publication Date: 2009-01-07
ZHEJIANG UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The process has high energy consumption, many unit operations, long production cycle, and troublesome post-processing

Method used

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  • Method for preparing Ethyl 2-(2-aminothiazole-4-yl)-2-hydroxyiminoacetate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The ratio of the amount of feed material is ethyl acetoacetate: n-propyl nitrite: bromine: thiourea=1.0: 1.5: 1.3: 2.0. The inorganic base is sodium bicarbonate; the alcoholic solvent is ethanol, and the total consumption is 6 times of the input mass of ethyl acetoacetate.

[0032] (1) In a 3L three-necked flask, add ethyl acetoacetate (208.0g, 1.6mol), ethanol (624.0g), 0°C (t 1 ) was slowly added dropwise n-propyl nitrite (213.6g, 2.4mol), and the oximation reaction time was 8 hours (T 1 ), the resulting reaction solution was directly used for the bromination reaction.

[0033] (2) At 8°C (t 2 ), dropwise the mixed solution of bromine (332.8g, 2.08mol) and ethanol (624.0g), the bromination reaction time was 6 hours (T 2 ), the resulting reaction solution was directly used for the cyclization reaction.

[0034] (3) In a 3L four-necked flask, add an aqueous solution (concentration 20%) of thiourea (243.2g, 3.2mol), and control the temperature at 28°C (t 3 ), dropwi...

Embodiment 2

[0036] The molar ratio of the feed materials is ethyl acetoacetate: n-propyl nitrite: bromine: thiourea=1.0:2.0:1.1:1.5. Inorganic base is sodium carbonate; Alcohol solvent is n-propanol, and total consumption is 6 times of ethyl acetoacetate input quality (in step (1) and step (2), n-propanol consumption is respectively 3 times of ethyl acetoacetate quality ).

[0037] Others are the same as embodiment 1. The yield is 77.1%, the melting point is 185.5-186.1°C, and the HPLC purity is 99.45%.

Embodiment 3

[0039] The molar ratio of the feed materials is ethyl acetoacetate: n-propyl nitrite: bromine: thiourea=1.0:0.8:1.1:4.0. Inorganic base is sodium hydroxide; Alcohol solvent is methyl alcohol, and total consumption is 15 times of ethyl acetoacetate input quality (methanol consumption is 10 times of ethyl acetoacetate in the step (1), and methyl alcohol consumption is in the step (2). 5 times that of ethyl acetoacetate).

[0040] Others are the same as embodiment 1. The yield of demethylaminothiaxamic acid ethyl ester was 72.6%, the melting point was 185.6-186.1°C, and the HPLC purity was 99.51%.

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Abstract

The invention relates to a method for preparing ethyl-demethy laminothiazolyloximate, which comprises the following steps: oximate is performed on acetylacetic ether by using nitrous acid ester in alcohol solvent, and then cyclization is performed between the solution and thiourea through bromination to prepare ethyl-demethy laminothiazolyloximate. The method mainly has the beneficial effects that both oximate and bromination intermediates need no separation and purification, and are used in the next reaction directly, so the operating steps are simplified, the route is advanced, the reaction condition is mild, the operating steps are simplified, the unit operation is avoided, the post-processing is simple, the manufacture cost is low, the yield is higher, the production of the three wastes is less, and more important implementary value and the social and economic benefits are realized.

Description

(1) Technical field [0001] The invention relates to a preparation method of ethyl demethylaminothiaxate. (2) Background technology [0002] Demethylaminothiaxamate ethyl ester is mainly used in the synthesis of cephalosporins, and is an important intermediate of cefotaxime, ceftriaxone, ceftazidime and other drugs. [0003] Before the present invention was made, the synthesis of demethylthiaxamic acid ethyl ester in the prior art mainly had the following routes: [0004] (1) With ethyl acetoacetate as raw material, there are mainly two approaches: [0005] 1) First oximation, then halogenation, and then cyclization. Specifically: in dichloromethane, under the promotion of dilute sulfuric acid, carry out oximation reaction with sodium nitrite, the obtained ethyl 2-hydroxime acetoacetate is then halogenated with thionyl chloride or bromine, and the excess is removed under reduced pressure after the reaction Halogenating agents and organic solvents; finally, thiourea cycliza...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D277/593
Inventor 钟为慧刘永亮苏为科顾士崇刘会军
Owner ZHEJIANG UNIV OF TECH
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