Abstract Phenalen-1-one was obtained in considerable yield by reducing 3- hydroxyphenalen-1-one. Most of known preparation methods are not very practical, either because their yields are very poor or because their processes have many steps. This regioselective 1, 2-reduction proceeded by the action of NaBH4 and various cations of rare- earth elements and metals. The yields of phenalen-1-one were examined as a function of ...