2,4-Diazidopyrrolo[2,3-d]pyrimidines: synthesis, ring–chain tautomerism and Cu(I)-catalyzed azide–alkyne cycloaddition reaction

Abstract

2,4-Diazidopyrrolo[2,3-d]pyrimidines were synthesized by the reaction of the corresponding 2,4-dichloropyrrolo[2,3-d]pyrimidines with sodium azide at room temperature. 2,4-Diazidopyrrolo[2,3-d]pyrimidines were shown to exist in an equilibrium with the corresponding 5-azidopyrrolo[3,2-e]tetrazolo[1,5-c]pyrimidine. The proportion of the tetrazole tautomer increases with increasing solvent polarity. The CuAAC reaction of the obtained azides with 3-methylphenyl- and 4-biphenylylethynes afforded the corresponding 2,4-bis(4-aryl-1,2,3-triazol-1-yl)pyrrolo[2,3-d]pyrimidines.