104 PTEROYLGLUTAMIC ACID 



light rapidly destroyed the biological activity. The liberation of p-amino- 

 benzoylglutamic acid paralleled that of biological inactivation which showed 

 that the first step in the reaction consists in a rupture in the bond between 

 the C^-methylene group and the N'" atom of aromatic amino group. 



C. CONSTITUTION 

 HOOC O ^^V^V-NH2 



CHNH— C— </ \>— NH— CH2- 



CH2 



^N^/ 



OH 



CH2 



I 

 HOOC 



Pteroylglutamic acid : N-[4- { [(2-amino-4-hydroxy-6-pteridyl)methyl]amino } - 

 benzoyl]glutamic acid 



D. SYNTHESIS 



The final proof of the structure of this compound was obtained by syn- 

 thesis of pteroylglutamic acid by different methods. The method of Waller 

 et al}'' utihzes the simultaneous condensation of 2,4,5-triamino-6-hydroxy- 

 pyrimidine (II), p-aminobenzoylglutamic acid (X), and a , /3-dibromopro- 

 pionaldehyde in aqueous solution. Pteroic acid was obtained by the cor- 

 responding reaction, except that p-aminobenzoic acid was used instead of 

 p-aminobenzoylglutamic acid. The procedure of Hultquist et al.^^ involved 

 the reaction of a , (8-dibromopropionaldehyde with pyridine, 2,4, 5-triamino- 

 6-hydroxypyrimidine (II), and potassium iodide to yield N-[(2-amino-4- 

 hydroxy-6-pteridyl) methyl] pyridinium iodide (XI). This was then treated 

 with p-aminobenzoylglutamic acid (X) in ethylene glycol to yield pteroyl- 

 glutamic acid. The position of the methylpyridinium group on the 6 posi- 

 tion of the pteridine was established by oxidation with alkaline perman- 

 ganate to yield 2-amino-4-hydroxypteridine-6-carboxylic acid (V). These 

 two methods of synthesis are schematically outlined in Fig. 6. 



Angler et al}^ condensed diethyl N-(p-aminobenzoyl)glutamate with re- 



33 M. E. Hultquist, E. Kuh, D. B. Cosulich, M. J. Fahrenbach, E. H. Northey, D. R. 

 Seeger, J. P. Sickels, J. M. Smith, Jr., R. B. Angier, J. H. Boothe, B. L. Hutchings, 

 J. H. Mowat, J. Semb, E. L. R. Stokstad, Y. Sul)baRow, and C. W. Waller, J. 

 Am. Chem. Soc. 70, 23 (1948). 



34 R. B. Angier, E. L. R. Stokstad, J. H. Mowat, B. L. Hutchings, J. H. Boothe, C. W. 

 Waller, J. Semb, Y. SubbaRow, D. B. Cosulich, M. J. Fahrenbach, M. E. Hult- 

 quist, E. Kuh, E. H. Northey, D. R. Seeger, J. V. Sickels, and J. M. Smith, Jr., 

 /. Am. Chem. Soc. 70, 25 (1948). 



