then are reacted with aqueous base to form the corresponding mixture of erythro amide free bases which are reacted with a suitable organic acid resolving agent in an alkyl alcohol solvent to form acid salts of the l erythro stereoisomers preferentially with respect to the d erythro stereoisomers the 1 erythro acid salts are then reacted with aqueous base to form the 1 erythro piperidine amide free base which in turn is epimerized to produce the desired d threo product by treating it in an organic solvent with an alkali metal alkoxide application_number US 79266197 A description this invention provides novel processes for stereoselective synthesis of a variety 2 substituted piperidine stereoisomers although preferred processes are those directed to the d threo stereoisomers those skilled in the art will recognize that the processes and techniques disclosed herein can be readily adapted to the synthesis of the other stereoisomer as well all such synthetic processes are within the scope of the present invention in one aspect the present invention is directed to synthetic methods involving hydrogenation of pyridines having formula i str3 wherein r 1 is aryl having about 6 to about 28 carbon atoms this hydrogenation can be effected by any of the numerous.