Method for preparing aspoxicillin trihydrate

The present invention discloses a method for preparing aspoxicillin trihydrate: a, D- aspartic acid and BTC in methanol reaction, the reaction solvent is added to precipitate aspartic -β- methyl ester hydrochloride; two , aspartic -β- methyl ester hydrochloride and methylamine solution reaction to produce D- aspartate -β- carboxamide; after the reaction, a solution of solvent, precipitation D- aspartate -β- A crude amide; D- aspartate -β- carboxamide the crude product after recrystallization from dry to give D- aspartate -β- carboxamide; three, D- aspartate -β- carboxamide and BTC in a solvent to produce D- aspartate -N- cyclic anhydride; after the reaction, the solvent, precipitated D- aspartate -N- cyclic anhydride; Fourth, D- aspartate -N- the reaction cyclic anhydrides and amoxicillin occurs in a solvent of acetonitrile and aqueous sodium hydroxide solution, the off part of carbon dioxide, to obtain aspoxicillin crude; aspoxicillin crude product after bleaching, recrystallization, filtration and drying, to obtain a flutter amoxicillin trihydrate.