THE STEREOSELECTIVE REDUCTION OF α-AMINOPROPIOPHENONE DERIVATIVES WITH SODIUM BOROHYDRIDE
The ratio of erythro and threo products from the sodium borohydride reduction of the hydrochlorides, and other acid salts, of α-aminopropiophenone derivatives was determined.It was found that this procedure resulted in stereoselective formation of erythro-2-amino-1-phenylpropanols in contrast to sodium borohydride reduction of the corresponding free bases.The method was successfully applied to the synthesis of dl-erythro-2-(4-benzylpiperidino)-1-(4-hydroxyphenyl)propanol which has been used as a vasodilator.