441 



Pyrroles, Porphyrins and Related Compounds 



(b) COoH 



CH2 CH3 \ XHi.CO^H (c) 



CH2.CH2.CO2H (d) 



(g) HO2C.CH2 



(f) H02C.CH2.CK CH3 '-"3 



CH2.CH2.CO2H (e) 

 Cobyrinic Acid 



CONH 

 / 

 CONH2CH3 CH2 u 



/ H V 

 CH^ *?">N^ CN/^-pl^ 



CH3 





NH2 



-CO 



/ AM 



NH OH 



/ O©/ 



CH2 / / 



a-(5,6-Dimethylbenzimidazolyl) cobamide Cyanide 



The nucleotide-free carboxylic acid form is called co- 

 byrinic acid, the carboxyl groups (amides, etc.) being let- 



