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.
This is a continuation of U.S. patent application Ser. No. 08/382,649, filed Feb. 2, 1995, now U.S. Pat. No. 5,750,703, which is a continuation of U.S. patent application Ser. No. 08/083,102, filed Jun. 24, 1993 now abandoned.
Processes are disclosed for preparing piperidine derivative compounds of the formulae I, II or III: ##STR00001## The processes involve reacting a compound of formula Ia, IIa or IIIa ##STR00002## with isobutyrate or an isobutyrate equivalent.
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.
