The reduction of various salts of 1-(4-benzyloxy and hydroxy)-2-(4-benzylpiperidinopropan-1-one (4a and b) with sodium borohydride gave the corresponding erythro-alcohols (5a and b) stereoselectively, and the relative configuration of the threo- and erythro-alcohols (5a and b) was determined by the stereospecific transformation to the cis- and trans-1-(4-methoxyphenyl)-2-methylethylene oxides (7). In addition, the reactions of the trans-epoxide (7), and 4-acetoxy- and 4-nitroderivatives (8a and b) with 4-benzylpiperidine, in order to prepare 2-piperidino-1-propanol derivatives which would be readily transformed to the 5a and b were examined, but these reactions gave mainly the regioisomer, 1-piperidino-2-propanol derivatives (9a, b and c).
