- Synthesis method for flupirtine maleate compound
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The invention discloses a synthesis method for a flupirtine maleate compound. The method comprises the steps that 2-amino-3-nitro-6-chloropyridine (a first compound) is used as a starting material to react with fluorobenzylamine (a second compound) to generate 2-amino-3-nitro-6-p-fluorobenzylamine pyridine (a third compound), the third compound is processed through di-tert-butyl dicarbonate ester protection to obtain 2-amino-3-nitro-6-p-fluorobenzylamine pyridine-3-based-tert-butyl acetate (a fourth compound), the fourth compound is processed through hydrogenation reduction and then react with ethyl chloroformate, after reacting is finished, deprotection is performed to obtain flupirtine hydrochloride (a fifth compound), and the fifth compound is salified with maleic acid to obtain flupirtine maleate (the sixth compound). According to the synthesis method, the starting material is cheap and easy to obtain, byproduct generation is avoided through amino protection, therefore, the impurity content is decreased, and the product quality is improved; catalytic reduction is performed by adopting palladium chloride, the reaction condition is mild, the reaction process is easy to operate, and the method is suitable for industrial production.
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- Process for the preparation of pure flupirtine maleate and its A modification
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A process for preparation of pure flupertine maleate and the pure A crystalline form of flupertine maleate by the use of water soluble alcohols during synthesis and/or purification.
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- 2-Amino-3-carbethoxyamino-6-(p-fluoro-benzylamino)-pyridine-maleate
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There is prepared 2-amino-3-carbethoxyamino-6-(p-fluoro-benzylamino)-pyridine-maleate of the formula STR1 The compound has antiphlogistic and analgesic properties in the same manner as the known hydrochloride salt. In contrast to the hydrochloride 2-amino-3-carbethoxyamino-6-(p-fluoro-benzylamino)-pyridine-maleate can be produced without a disturbing blue coloration. This maleate generally is formed from a mixture of two crystal modifications A and B, whereby there is especial advantageous in regard to isolation as well as the galenical preparations a mixture entriched in modification A (60 to 90% modification A).
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