A [3.1.0]-Fused 2',3'-Modified β-D-Pyrazolo[3,4-d]pyrimidine Nucleoside

The furanose ring in 4,6-bis(methylthio)-2-(2,3-anhydro-1-deoxy-β-D-allofuranosyl)-2H-pyrazolo[3,4-d]pyrimidine, C 13 H 16 N 4 O 4 S 2 , is almost planar with the epoxide ring in an exo orientation.