4‐Azapteridines. I. Covalent addition products of the pyrazino[2,3‐e]‐as‐triazine ring system

Abstract
Ring closure of 5, 6‐diamino‐3‐methylthio‐as‐triazine with 40% aqueous glyoxal provided the 6, 7‐dihydrate of the pyrazino[2, 3‐e]‐as‐triazine (4‐azapteridine) ring system. The C7 hydroxy group of this dihydrate underwent exchange in methanol or ethanol affording the 7‐alkoxy, 6‐hydroxy derivatives.