A Convenient Synthesis of Pyrazolo[3,4-d]pyrimidine-4,6-dione and Pyrazolo[4,3-d]pyrimidine-5,7-dione Derivatives

摘要

Pyrazolo-[3,4-d]pyrimidine-4,6-diones 5 and pyrazolo[4,3-d]pyrimidine-5,7-diones 7 were synthesized by Curtius rearrangement of pyrazolic mono-esters 2 and 3 followed by hetero-cyclization via the ureas derivatives 4 and 6 under alkaline conditions.