Coy W. Waller

SYNTHESIS OF PTEROYLGLUTAMIC ACID (LIVER L. CASEI FACTOR) AND PTEROIC ACID

Upon completion of the degradation of the Luctobacihs c a m factors and the synthesis of the fragments, the structure of the liver L. casei factor was proposed. The fermentation factor and the liver factor differed in the number of glutamic acid residues. The structure for the liver compound showed only one glutamic acid, while the fermentation factor appeared to contain three such residues. Both factors yielded p-aminobenzoic acid and the same pteridines upon degradation. On this basis, both factors appeared to have the same pteridine nucleus attached to the p-aminobenzoic acid, as indicated in the proposed structure for the liver factor. The chemical name is obviously too long for general usage. For the basic nucleus, a name iodicating its pterin nature is desirable. Thus, the name “Pteroylglutamic Acid” is proposed for the liver L. casei factor. The fermentation L. casei factor and analogous cornpounds containing various amino acids can also be named as pteroyl derivatives. The basic structure for these compounds would, accordingly, be called “Pteroic Acid.” The syntheses of pteroylglutamic acid and pteroic acid are reported herein.

STRUCTURE AND SYNTHESIS OF THE PTERIDINE DEGRADATION PRODUCTS OF THE FERMENTATION L. CASEI FACTOR

The two preceding papers of this series have indicated the nature of the degradation products obtained from the fermentation Lactobacillus casei factor1: namely, the dl liver L. cnsei factor, p-aminobenaoic acid, pyrrolidonecarboxylic acid, 1 (+ ) glutamic acid, 2-amino4 hydroxy 6 pteridinecarboxylic acid,+ and 2 amino 4 hydroxy 6 methylpteridine. The first four of these substances were known compounds and could be readily identified, whereas the two pteridine compounds were new substances which required further degradation, as well as synthesis, in order to establish their structure. The above 2-amino-4-hydroxy-6-pteridinecarboxylic acid was first isolated from the oxidative alkaline hydrolysate of the fermentation L. casei factor. The empirical formula determined from analytical data, the ultraviolet absorption spectrum, the titration curve, and the positive test for guanidine, all of which have been described in the preceding papers, led us to suspect the presence of a pteridinecarboxylic acid. Decarboxylation of a few milligrams of the substance liberated a little less than one mole of carbon dioxide, and the residue, when purified, appeared to resemble 2-amino-4-hydroxypteridine, a substance which we had synthesized by reacting 2,4,5-triamino-6-hydroxypyrimidine with glyoxal. The synthesis of the 2-amino-4-hydroxy-6-pteridinecarboxylic acid was then effected by reacting 2,4,5triamino-6-hydroxypyrimidine with kctomalonic ester, to give isoxanthopterin carboxylic acid2 which was chlorinated with a mixture of phosphorus pentachloride and phosphorus oxychloride. The chlorine group wag then replaced with hydrogen by reduction of the chloro com-

Synthesis of substituted pteridines

ConclusionsThe cyclocondensation of 2,5,6-triamino-4-oxo-3,4-dihydropyrimidine and tetraaminopyrimidine with butylthioacetone and 2-butylthiopropanal gives 7-methylpteridines, while the reaction of these pyrimidine derivatives with 2-phthalimidopropanal, 1,1-dibutoxyacetone, 1,1-dichloroacetone, and 1,1-dibromoacetone gives mixtures of 6- and 7-methylpteridines.