Heterocyclic studies. Part VII. Action of methoxyamine and methylhydrazines on 4-hydroxypteridine and its methyl derivatives

Abstract

Unsymmetrical dimethylhydrazine reacted with 4-hydroxypteridine and its 2-methyl derivative to give mixtures of an aminopyrazine carboxamide (III; R²= R³= H), an aminopyrazine carbohyrazide (IVb; R²= R³= H), and 4,5-diamino-6-hydroxypyrimidine (IX; R¹= H or Me). The 6- and 7-methyl and 6,7- and 2,7-dimethyl derivatives of 4-hydroxypteridine gave analogous products except that no pyrimidine derivative was obtained in these cases. Methylhydrazine degraded 4-hydroxypteridines similarly.

4-Hydroxypteridine and its 2- and 6-methyl derivatives were cleaved by methoxyamine to yield 4,5-diamino-6-hydroxypyrimidines (IX; R¹= H or Me) and in two cases pyrazine derivatives (VIc; R²= H or Me, R¹= R³= H) which still contained all the carbon atoms of the original pteridines. 4-Hydroxy-7-methylpteridine and methoxyamine gave only the pyrazine derivative (Vlc; R¹= R²= H, R³= Me) while 2,7- and 6,7-dimethyl-4-hydroxypteridine gave methyl aminopyrazine carbohydroxamates (IVc; R²= H or Me, R³= Me) under the more vigorous conditions necessary for their cleavage.

¹ H N.m.r. data for the products are recorded and possible mechanisms for pyrazine ring cleavage are suggested.