Synthesis of 7H‐tetrazolo[1,5‐c]pyrrolo[3,2‐e]pyrimidines and their reductive ring cleavage to 4‐aminopyrrolo[2,3‐d]pyrimidines

Some new 7,9‐disubstituted 7H‐1,2,3,4‐tetrazolo[1,5‐c]pyrrolo[3,2‐e]pyrimidines5have been synthesized either by diazotization of 4‐hydrazino‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines4obtained by hydrazinolysis of 4‐chloro‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines3orviaa substitution reaction between3and sodium azide. 5,7‐Disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidin‐4(3H)‐ones2were obtained by cyclocondensation of 2‐amino‐3‐cyano‐1,4‐disubstituted pyrroles1with formic acid which on chlorination using phosphorus oxychloride afforded3. A novel route for the synthesis of 4‐amino‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines6by the reductive ring cleavage of5has been reported.