In the presence of 10% NaOH in boiling MeOH enantiomerically enriched HPPH is racemized. This permits the deracemization of HPPH in the presence of brucine, giving enantiomerically pure (-)-(S)-HPPH [(-)-(S)-5-(4-hydroxyphenyl)-5-phenylhydandoin]. (C) 2004 Elsevier Ltd. All rights reserved.