Easy Access to 1 H ‐Pyrrolo[3′,4′:5,6]pyrido[2,3‐ d ]pyrimidine‐2,4,6,8(3 H ,7 H )‐tetraone and Selectively N 7 ‐Substituted Analogues through Key Synthons

To synthesize unsubstituted pyrrolo[3′,4′:5,6] pyrido[2,3‐ d ]pyrimidine‐2,4,6,8‐tetraone, we have developed new synthon 4‐formyl‐3‐hydroxy‐2,5‐dioxo‐2,5‐dihydro‐1 H ‐pyrrole, which was then treated under mild conditions with 6‐aminouracil. This new synthetic pathway could be extended to the preparation of N 7 ‐selectively substituted heterocycles by starting either from this new synthon or from its N ‐substituted analogues. Examples of N 1 , N 7 ‐disubstituted and N 1 , N 3 , N 7 ‐trisubstituted derivatives are also described. We have thus developed new synthons that lead to easy access to the unsubstituted pyrrolo[3′,4′:5,6]pyrido[2,3‐ d ]pyrimidine‐2,4,6,8‐tetraone skeleton and to selectively N 7 ‐substituted analogues.