Synthesis of 8-(ω-Chloroalkyl)-dipyrrinones

Dipyrrinones,typically bright yellow compounds with a long axis-polarized π-π* excitation in the 14π-electron-conjugated chromophore,such as xanthobilirubic acid methyl ester(XBRMe),are useful building blocks for the syntheses of biologically important tetrapyrrole pigments such as bilirubin(the yellow pigment of jaundice)[1],and they have been extensively used as model dipyrrole pigments for the spectroscopic and the photochemical studies of liner tetrapyrroles such as bilirubin and biliverdin.They have also served as useful adjuncts in the studies of jaundice phototherapy and in bilirubin structure-biological function relationships[2].