- Preparation method of zopiclone intermediate
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The invention provides a preparation method of zopiclone. According to the method, anhydride is used as a reaction solvent, pyrazine-2,3-dianhydride and 2-amino-5-chloropyridine are synthesized into 6-(5-chloro-2-pyridyl)-5,7-dioxo-6,7-dihydro-5H-pyrrolo(3,4-b)pyrazine in one step, so that the process is simplified, the obtained product is high in yield and purity, production conditions and environment friendliness are achieved, and the method is suitable for industrial production.
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Paragraph 0024-0064
(2020/06/17)
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- Preparing method for N-substituted pyrrolo [3,4-B] pyrazine-5,7(6H)-diketone
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The invention relates to a preparing method for a dexzopiclone intermediate N-substituted pyrrolo [3,4-B] pyrazine-5,7(6H)-diketone, in particular to preparation of 6-(5-chloropyridine-2-yl)-5H-pyrrolo [3,4-B] pyrazine-5,7(6H)-diketone. According to the preparation method, N-substituted pyrrolo [3,4-B] pyrazine-5,7(6H)-diketone is prepared with triphosgene/triphenylphosphine oxide serving as a reaction reagent, as the product is a crystalline solid and is slightly soluble in an organic solvent while a catalyst is soluble in the organic solvent, the product can be obtained through direct suction filtration, and posttreatment is convenient; besides, a mother solution can be directly and consecutively reused, cyclic use of aryl oxide phosphate and the solvent is achieved, and the preparing method has the advantages that operation is simple, the reaction conditions are mild, the yield is high, and the quantity of three wastes is small; use of highly-corrosive toxic reagents such as thionyl chloride and chloroformate is avoided from the source, and high implementation value and social and economic benefits are achieved.
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Paragraph 0019; 0020; 0021; 0026; 0027; 0028-0035
(2017/08/23)
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- A method for producing zopiclone
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The invention relates to a preparation method of zopiclone for improving sleeping, belonging to the field of medicines. In the preparation process of 6-(5-chlro-2-pyridyl)-5, 7-dioxo-5, 6-dihydropyrrolo[3, 4-b] pyrazine, namely a compound 3, by taking DMAP (dimethylaminopyridine) as a catalyst, in the presence of triethylamine, cyclization is directly carried out to synthesize an intermediate 3. The crude product yield is 85%, the yield is improved, the operation is simplified, and irritant reagents such as acetic anhydride, thionyl chloride, ethyl chloroformate and the like are not used, thereby facilitating production, facilitating recovery of xylene as a solvent and reducing emission of three wastes. Zopiclone is further synthesized by the compound 3. The method is concise in whole line, simple and convenient to operate and more suitable for industrialized production.
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Paragraph 0025; 0026
(2017/01/05)
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- Preparation method for pyrrolo-pyrazine
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The invention discloses a preparation method for pyrrolo-pyrazine. The preparation method comprises the following steps that 1, levo-zopiclone (I) is dissolved into organic solvent, the pH is regulated to 8-10, and heating reflux is performed; 2, water is added, stirring is performed, standing is performed for layering, and a water layer is separated out; 3, the step 2 is repeated; 4, a drying agent is added in an organic layer for drying, filtering is performed, and filtrate is concentrated under reduced pressure until the filtrate is dried into a compound (II); 5, the compound (II) is dissolved into the organic solvent, an oxidizing agent is added, heating reflux oxidation is performed, filtering is performed, filtrate is concentrated under reduced pressure, cooling and crystallizing are performed, filtering is performed, and solids are dried to obtain the pyrrolo-pyrazine (III). According to the method, the by-product levo-zopiclone generated in eszopiclone production can be taken as the raw material to generate the pyrrolo-pyrazine (III) through reacting, the pyrrolo-pyrazine (III) generates zopiclone according to a conventional technique, waste utilization is maximized on the premise that the quality is guaranteed, and discharge of three wastes is greatly reduced.
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Paragraph 0043
(2016/11/09)
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- IMPROVED PROCESS FOR THE PREPARATION OF ZOPICLONE AND IT'S ENANTIOMERICALLY ENRICHED ISOMER
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Present invention relates to an improved process for the preparation of Zopiclone and its enantiomerically enriched isomer (Eszopiclone). 6-(5-Chloropyridin-2- yl)-5-hydroxy-7-oxo-5,6-dihydropyrrolo [3,4-b] pyrazine is reacted with 1-chloro- carbonyl-4-methylpiperazine in the presence of alkali earth metal carbonates, hydroxides or oxides in a solvent medium to give Zopiclone. It is reacted with optically active acid in a mixture of water and water miscible organic solvent followed by work up to give Eszopiclone. The present invention also relates to process for the conversion of (R) or (S) Zopiclone to 6-(5-chloropyrid-2-yl)-5-hydroxy-7-oxo-5,6-dihydro- pyrrolo- [3,4-b] - pyrazine of the intermediate which can be converted to racemic Zopiclone.
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- Process for the preparation of eszopiclone
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The invention relates to a process for making of 6-(5-chloro-2-pyridinyl)-6,7-dihydro-7-oxo-5H-pyrrolo-[3,4-b] pyrazin-5-yl-4-methyl piperazine-1-carboxylate, also known as zopiclone. The invention further describes an effective method for resolving of zopiclone into its enantiomers (eszopiclone and (R)-zopiclone) and also provides a method of recycling of (R)-zopiclone.
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Page/Page column 5
(2008/12/06)
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