Syntheses of 2-fluoroformycin [7-amino-5-fluoro-3-(beta-D-ribofuranosyl)pyrazolo[4,3-d]pyrimidine] (2b) and 2-aminoformycin [5,7-diamino-3-(beta-D-ribofuranosyl)pyrazolo[4,3-d]pyrimidine] (2c) are described. Cytotoxicity data are given for 2b and 2c alone as well as with added pentostatin. Kinetic parameters for adenosine deaminase are also provided. 2-Fluoroformycin, although a much poorer substrate for adenosine deaminase than formycin A, is not nearly as cytotoxic to cells in culture.
