Abstract:
The synthesis of some 4-oxypyrimido-(4,5-d)- pyrimidines and 2:4-dioxypyrimido-(4,5-d)- pyrimidines is reported. The synthesis is effected by the cyclization of the respective 2- substituted -4-aminopyrimidine -5-carboxamides by treatment with ethyl orthoformate -acetic anhydride mixture and diethyl carbonate. In the case of 2-mercapto amino-carboxamido-pyrimidine, the former procedure, however, leads to etherification of the mercapto group in addition to ring closure.
