116 



PTEROYLGLUTAMIC ACID 



CHg 



N 



OH 



XX 



(2-Amino-4-hydroxy-6- 

 methylpteridine) 



CH3-^^\/^yNH. 



CH3 



(2- Amino-4-hydroxy-6, 7- 

 dimethj'lpteridine) 



H 



H 



H 

 H 



•VN\/N,\_ 



CH3— 7 

 H 



NH, 



H 

 CHs^ 



^nA,, 



N 



1— NHo 



y 



CHO OH 

 XXII 



H I I 

 CHO OH 



XXIII 



(2-Amino-4-hydroxy-5-formyl-6- (2-Amino-4-hydroxyl-5-formyl-6,7- 



methyl-5, 6, 7, 8-tetrahydropteridine) dimethyl -5, 6, 7 , 8-tetrahydropteridine) 



preparation of 2-amino-4-hydroxy-5-f ormyl-6 , 7-diphenyl-8-ethyl-5 ,6,7,8- 

 tetrahydropteridine (XXV) ^"^ by reduction and formylation of 2-amino-4- 

 hydroxy-6 , 7-diphenyl-8-ethyl-7 , 8-dihydropteridine (XXIV). ^^ The reduc- 



C0H5 



C2H5 



H 



CeH.V^^\/^% 



H 

 CeHs — 



CfiHs 



-NH2 



N 



y 



CeHo 

 H 



-NH2 



N 



OH 



XXIV 



(2-Ainino-4-hj'droxy-6,7-diphenyl- 

 8-ethyl-7, 8-dihydropteridine) 



OH 

 HC=0 



XXV 



(2-Amino-4-h3'droxy -5-f ormyl-6, 7-dipheny I - 

 8-ethyl-5, 6, 7, 8-tetrahydropteridine) 



tion in 98 to 100% formic acid and formylation in the presence of acetic 

 anhydride are carried out under the same conditions as those used to prepare 

 the 6-methylpteridine model (XXII). The resulting product (XXV) reacts 

 similarly to XXII; thus, it has the same polarographic behavior, the formyl 

 group is stalile in 0.1 V sodium hydroxide, and 1 mole of nitrous acid is 

 consumed only after treatment with mineral acid at pll 2. In this case, the 

 original dihvdropteridine (XXIV) was isolated after reaction with nitrous 



33 H. S. Forrest, R. Hull, H. J. Rodda, and A. R. Todd, J. Chcm. Soc. 1951, 3. 



