| 摘要 |
The present invention relates to a process for preparation of substantially pure piperidine derivative compounds of the formulae: <IMAGE> or <IMAGE> wherein R1 is hydrogen or hydroxy; R2 is hydrogen; or R1 and R2 taken together form a second bond between the carbon atoms bearing R1 and R2; R3 is -COOH or -COOR4; R4 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.
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