The present invention provides a process for the production of calcium salts of hydantoic acids and which comprises the steps of reacting a hydantoin with a calcium base material such as calcium hydroxide in an aqueous medium at a sufficient temperature and for a sufficient period of time to form the calcium salt of the corresponding hydantoic acid and then separating the calcium salt of such acid from the reaction mass. This separation can include the further steps of cooling the reaction mass down to facilitate the precipitation of the acid/salt crystals and then separating the precipitate by means of filtering or centrifugating. These acids can then be subjected to a HNO.sub.2 -mediated decarbamoylation process followed by an optical resolution step to thus provide high yields of D-p-hydroxyphenylglycine which is a key synthetic immediate or building block for semi-synthetic penicillin and cephalosporins.
本发明提供了一种生产
咪唑酸
钙盐的方法,包括以下步骤:在足够的温度和时间下,在
水性介质中将
咪唑酮与
钙碱性物质(如
氢氧化钙)反应,形成相应
咪唑酸的
钙盐,然后从反应物中分离出该酸的
钙盐。这种分离可以包括进一步的步骤,即将反应物冷却以促进酸/盐晶体的沉淀,然后通过过滤或离心分离沉淀物。这些酸随后可以经过HNO.sub.2介导的脱
氨酰化过程,然后进行光学分辨步骤,从而提供高产量的D-p-羟基苯甘
氨酸,这是半合成
青霉素和
头孢菌素的关键合成中间体或构建块。