SYNTHESIS OF BILIVERDIN IXγ (PTEROBILIN)

Article abstract of DOI:10.1016/S0040-4020(01)88698-1

Condensation of a bis(acetoxyethyl)pyrromethane dicarboxylic acid (11d) with a diformylpyrroketone (12b) afforded a bis(acetoxyethyl)-γ-meso-hydroxyporphyrin (13d) which was converted into the related bis(chloroethyl)-γ-benzoyloxyporphyrin (14f).The Zn complex of the latter was transformed by brief treatment with base, followed by chloromethylethyl ether into the zinc bis(chloroethyl)-γ-ethoxymethoxyporphyrin (20b).Dehydrochlorination with potassium t-butoxide in t-butanol, and acid catalysed demetallation and deprotection then afforded the somewhat unstable blue γ-oxyprotoporphyrin dimethyl ester (21).The Fe-complex of the latter readily underwent oxidative ring opening by aerial oxidation in pyridine, and after demetallation gave biliverdin IXγ (pterobilin) dimethyl ester (22).