1-[2-hydroxy-5-(phenylmethoxy)phenyl]-3-phenyl-1-Propanone is the labeled analogue of 1-[2-hydroxy-5-(phenylmethoxy)phenyl]-3-phenyl-1-Propanone (CAS 200434-98-6), a reactant used in the synthesis of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone (P757500).