/ 



in. INDUSTRIAL PREPARATION" 573 



CO CO 



/ \ 



R— N N— R R— N N— R 



II II 



lie CH — > HC CH 



I i_ II 



H2C C — CHCH2CH2OC2HB HjC CH — CH2CH2CH2OC2HS 



\ / \ / 



s s 



IX X 



CO CO 



/ \ / \ 



R— N N— R R— N N— R 



II II 



HC CH -^ HC CH -♦ 



II II 



H2C CH H2C CH 



\ / \ \ / \ 



S CHj S CH2 



/\ I /\ I 



Br CH2 CHj X CH2 CH.. 



XI XII 



CO CO 



/ \ / \ 



R— N N— R HN NH 



II II 

 HC CH COOC2H5 HC CH 



II I II 



H2C CH— CH2CH2CH2CH -» H2C CH— CH2CH2CH2CH2COOH 



S COOC2H, 



XIII 



XIV 



H2N NH2 



I I 



HC CH 



R = Benzyl | | 



H2C CH— CH2CH2CH2CH2COOH 



X = (f-Caraphsulfonic \ /^ 



acid ion S 



XV 



Starting material is fumaric acid (I), which is converted via meso- 

 dibromosuf'cinic acid (II) to meso-a, /3-bisbenzylamiiiosuecimc acid (III). 

 The diamino acid is reacted with phosgene, gi\'ing 1 ,3-dil)enzyi-2-imidazoh- 

 done-a's-4 , 5-dicarboxyhc acid (IV). The anhydride (V) of the latter is then 

 reduced with zinc in an acetic acid-acetic anhydride mixture forming the 



