Abstract: The present invention is related to a novel process for preparing certain piperidine derivatives which are useful as antihistamines, antiallergy agents and bronchodilators, these piperidine derivatives can be described by the following formulas: ##STR1## wherein R.sub.1 represents hydrogen or hydroxy;R.sub.2 represents hydrogen; orR.sub.1 and R.sub.2 taken together form a second bond between the carbon atoms bearing R.sub.1 and R.sub.2 ;n is an integer of from 1 to 5;R.sub.3 is --CH.sub.2 OH, --COOH or --COOalkyl wherein the alkyl moiety has from 1 to 6 carbon atoms and is straight or branched;each of A is hydrogen or hydroxy; andpharmaceutically acceptable salts, hydrates and individual optical isomers thereof.