Process for production of piperidine derivatives

The present invention relates to a process for preparing piperidine derivative compounds of the formulae: ##STR1##

wherein

• n is 0 or 1;
• R¹ is hydrogen or hydroxy;
  • R² is hydrogen;
  • or, when n is 0, R¹ and R² taken together form a second bond between the carbon atoms bearing R¹ and R², provided that when n is 1, R¹ and R² are each hydrogen;
  • R³ is -COOH or -COOR⁴;
  • R⁴ is an alkyl or aryl moiety;
  • A, B, and D are the substituents of their rings, each of which may be different or the same, and are selected from the group consisting of hydrogen, halogens, alkyl, hydroxy, alkoxy, and other substituents,

    The process comprises providing a regiosomer of the following formula: ##STR2##

    wherein

• Z is -CG¹G²G³, ##STR3##
• m is an integer from 1 to 6;
• Q and Y are the same or different and are selected from the group consisting of O, S, and NR⁵;
• G¹, G², and G³ are the same or different and are selected from the group consisting of OR⁸, SR⁸, and NR⁸R⁹;
• R⁶ and R⁷ are the same or different and are selected from the group consisting of hydrogen, an alkyl moiety, an aryl moiety, OR⁸, SR⁸, and NR⁸R⁹; and
• R⁵, R⁸, and R⁹ are the same or different and are selected from the group consisting of hydrogen, an alkyl moiety, and an aryl moiety

  and converting the regioisomer to the piperidine derivative compound with a piperidine compound.