A facile synthesis of [1,2,4]triazino[3,2‐<i>f</i>]purines and [1,2,4]triazepino[3,2‐<i>f</i>]purines

Abstract

Abstract [1,2,4]Triazino[3,2‐ f ]purines 3a‐e and [1,2,4]triazepino[3,2‐ f ]purine 5 were synthesized by the reaction of 7,8‐diamino‐1,3‐dimethylxanthine 1 with diketones such as glyoxal, diacetyl, dibenzoyl, pyruvic aldehyde dimethyl acetal, phenylglyoxal or acetylacetone in acetic acid in the presence of boric acid or polyphosphoric acid.