An efficient synthesis of symmetric bilindiones. Mesobilirubin-XIIIα and analogs with varying alkanoic acid chain lengths

Article abstract of DOI:10.1055/s-1992-26102

An inexpensive gram-scale, three-step procedure is described to convert methyl xanthobilirubinate and it alkanoic acid ester analogs (methyl 5-[(3-ethyl-1,5-dihydro-4-methyl-5-oxo-2H-pyrrol-2- ylidene)methyl]-1,4-dimethylpyrrol-3-ethanoate, -propanoate, -butanoate, -pentanoate, -hexanoate) into mesobilirubin-XIIIα and analogs in >90% yield at each step.