A simple, diastereoselective, inexpensive, and efficient route for the synthesis of highly functionalized
piperidines by the condensation of β-keto-esters, aromatic aldehydes and anilines using H3PW12O40 as a catalyst is
described. The catalyst could be easily recovered after completion of the reaction and reused without a considerable
change in its activity. Furthermore, in most cases the piperidine precipitates out of solution.