Three regioisomeric bilirubins and biliverdins with propionic acids replaced by benzoic acids were synthesized from the corresponding xanthobilirubicacids by oxidative coupling. The rubins were found to exhibit widely varying polarity, spectroscopic properties, and stereochemistry. The isomer with ortho benzoic acids (1o) was much less polar than either the meta (1m) or para (1p) because 1o (but not