SYNTHESIS OF THE PORPHYRIN NUCLEUS 



635 



AC P 



M P 



V 



\' 



M V 



V 



♦ coproporphyria I 



> »• coproporphyrin III 



> (coproporphyrin II) 



♦ (isomeric protoporphyrin) 



> *■ protoporphyrin IX 



(isomeric protoporphyrin) 



J tetravinyl- and 

 [^ trivinylporphyrins 



Fig. 3. Theory of porphyrinogenesis of Turner (/940): 

 ( — I-*) possibilities not taken into account. 



