An Efficient Synthesis of Symmetric Bilindiones. Mesobilirubin-Xlllα and Analogs with Varying Alkanoic Acid Chain Lengths

Abstract

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.