Heterocyclic studies. Part VIII. 2-Phenylpteridine and some related compounds

Abstract

Syntheses of 2-phenylpteridine and its 4- and 7-monomethyl, 4,7- and 6,7-dimethyl, and 4,6,7-trimethyl derivatives are described. Oxidation of 2-phenyl-, 7-methyl-2-phenyl-, and 6,7-dimethyl-2-phenyl-pteridine with hydrogen peroxide in glacial acetic acid gave the corresponding 4-hydroxy-derivatives. Further oxidation of 4-hydroxy-2-phenylpteridine gave 4,6,7-trihydroxy-2-phenylpteridine.

In acid solution 2-phenylpteridine gave a mixture of 3,4-monohydrated and 5,6,7,8-dihydrated cations which rapidly changed to a solution almost free of the monohydrate. 4-Methyl- and 4,7-dimethyl-2-phenylpteridine also gave essentially all 5,6,7,8-dihydrated cations but mainly 3,4-hydrated species were present in the equilibrium mixtures of cations formed from 7-methyl- and 6,7-dimethyl-2-phenylpteridine.

¹ H N.m.r. and u.v. spectra and pK_a values are recorded.