The present invention relates to substantially pure piperidine derivative compounds of the formulae: ##STR1## wherein R.sub.1 is hydrogen or hydroxy; R.sub.2 is hydrogen; or R.sub.1 and R.sub.2 taken together form a second bond between the carbon atoms bearing R.sub.1 and R.sub.2 ; R.sub.3 is --COOH or --COOR.sub.4 ; R.sub.4 has 1 to 6 carbon atoms; A, B, and D are the substituents of their respective rings each of which may be different or the same and are hydrogen, halogens, alkyl, hydroxy, alkoxy, or other substituents. A process of preparing such piperidine derivative compounds in substantially pure form is also disclosed.
本发明涉及以下式的基本纯丁啉衍
生物化合物:##STR1## 其中,R.sub.1是氢或羟基;R.sub.2是氢;或R.sub.1和R.sub.2在承载R.sub.1和R.sub.2的碳原子之间形成第二键;R.sub.3是--COOH或--COOR.sub.4;R.sub.4具有1到6个碳原子;A、B和D是它们各自环的取代基,每个取代基可以不同或相同,是氢、卤素、烷基、羟基、烷氧基或其他取代基。还公开了制备这种基本纯的
吡啶衍生物化合物的方法。