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-tetrazolo1,5-c]pyrrolo3,2-e]pyrimidines 5 have been synthesized either by diazotization of 4-hydrazino-5,7-disubstituted-7H-pyrrolo2,3-d]pyrimidines 4 obtained by hydrazinolysis of 4-chloro-5,7-disubstituted-7H-pyrrolo2,3-d]pyrimidines 3 or via a substitution reaction between 3 and sodium azide. 5,7-Disubstituted-7H-pyrrolo2,3-d]pyrimidin-4(3H)-ones 2 were obtained by cyclocondensation of 2-amino-3-cyano-1,4-disubstituted pyrroles 1 with formic acid which on chlorination using phosphorus oxychloride afforded 3 . A novel route for the synthesis of 4-amino-5,7-disubstituted-7H-pyrrolo2,3-d]pyrimidines 6 by the reductive ring cleavage of 5 has been reported.