Abstract
Two general rules are proposed for synthesizing unsymmetric from symmetric bile pigments based on a “reverse scrambling” strategy and polarity/acid-base properties of reactants and products, to facilitate separation of the target unsymmetrical bilirubin, such as mesobilirubin-VIIIα and others. By this method 17-desvinyl-17-ethyl-bilirubin-VIIIα, mesobilirubin-VIIIα, 12-despropionic acid-12-ethyl-mesobilirubin-XIIIα, 17-desvinyl-17-ethyl-bilirubin-XIIIα and 18-desvinyl-18-ethyl-bilirubin-IXα are synthesized.