SYNTHESIS AND PROPERTIES OF 2-AMINO-4-HYDROXY-5,6-DIMETHYL-5,6,7,8-TETRAHYDROPTERIDINE AND 5,7-DIMETHYL ISOMER

2-Amino-4-hydroxy-5,6-dimethyl-5,6,7,8-tetrahydropteridine, a useful model compound for studying chemical and enzymatic reactions of 5-methyl tetrahydrofolate, has been obtained in good yield as the hydrochloride by the following procedure: (a) anaerobic alkaline hydrolysis of 2,4-diamino-6-methylpteridine to the 4-hydroxy derivative; (b) catalytic hydrogenation of the latter compound to the tetrahydro stage; and (c) selective methylation at N-5 by treatment of the tetrahydropteridine with HCHO in the presence of KBH4. Both the 5,6-dimethyltetrahydropteridine and the 5,7-dimethyl isomer (prepared in a similar manner from 2,4-diamino-7-methylpteridine) were characterized with respect to absorption spectra, PMR spectra and pKa values of the N-5 methyl group. © 1969.