Dilevalol via resin-mediated epimerization: A case study. Reaction mechanism to reactor design to a viable process

A case study on a novel commercial process for the preparation of dilevalol , 5-[1-hydroxy-2-[(1-methyl-3-phenylpropyl)-amino]-ethyl]salicylamide, (R,R )-1, from crude (S,R)-1, is described. This covers all of the work from the initial laboratory observation of an acid-induced racemization of the benz ylic carbinol (epimerization) of pure (R,R)-1, to the identification and op timization of an acidic resin that facilitated the epimerization of the cor e-process-generated crude (S,R)-1 on a solid support, and the subsequent re actor modification culminating in a cost-efficient, industrial-scale, semi- continuous batch process for the preparation of dilevalol.