Activation and transfer of oxygen VII: Synthesis and spontaneous oxidation of some 1, 8‐blocked tetrahydropteridines

Abstract

AbstractSome tetrahydropteridines carrying methyl substituents at the N(1)‐, N(3)‐and N(8)‐positions were synthesized and subjected to autoxidation (V and XIII). A spontaneous oxidative contraction of the pyrimidine ring occurred in aqueous solution (XIII + O2 → XXI). This result was in agreement with a theory which has already been put forward.5‐Acetyl‐tetrahydropteridines were required for synthetic purposes. They could not generally be prepared by reduction of pteridines with zinc/acetic acid/acetic anhydride. A contraction of the pyrazine ring occurred in the attempted reductive acetylation of 1, 3, 6, 7‐tetramethylpteri‐2, 4‐dione (IX). The product was identified as 1, 3, 8‐trimethyl‐2, 6‐dioxopurine (XIV = 8‐methyl‐theophylline). Starting from 1, 3‐dimethylpteri‐2, 4‐dione the same procedure led to a mixture of two dimeric acetyl‐tetrahydropteridine derivatives.