Opsopyrrole carboxylic acid 



101 



M P 



HsOj 



M P 



HK)j 



M P 



H H H 



[31 



M U 



[2] 



HCN+HCl 



I'* 



M P 



M U 



HO 



U = CHjCHiNHCOiC.Hs 



N^H OHcA^H H^nA 



H 



H 



H 



IS] 



M U M P 



HO 



H H 



[7] 



:ei 



HCN + HCl 



OH 



[3] and [4] 



P — > U by the Curtius method 



via ester, hydrazide, and azide 



[f)l U ^ V 



CH2CH2NHCO2C2H5 



HCl 



M U MP 



P M M U 



HO 



AW^cm h/^n^^-^ 



•CH2CH2NH2 



H H 



OH 



L 



H H 



[8] 



MUMP P M M U 



HO 



H H H H 



M V M P P M M V 



OH 



HO 



H H H H 



OH 



exhaustive 



methylation 



of zinc complex 



.CH2CH2N(CH3)30H 



NaOH 



•CH = CH2 



followed by removal of Zn 



Biliverdin 



Fig. 6. Synthesis of biliverdin. 



