7-HALOGENATED 7-DEAZAPURINE 2 `-C-METHYLRIBONUCLEOSIDES

Abstract

7-Halogenated 7-deazapurine 2'-C-methylribonucleosides related to adenosine, inosine and guanosine were synthesized employing a ``one-pot'' glycosylation protocol (Vorbruggen glycosylation). The immunosine 2'-C-methylribonucleoside 4 was prepared by the same glycosylation strategy. By this route, the synthesis of the anti-HCV active compound 7-fluoro-7-deaza-2'-C-methyladenosine (1b) was notably simplified, while other nucleosides were synthesized for the first time. A single-crystal X-ray analysis of 7-fluoro-7-deaza-2'-C-methylinosine (2b) was performed showing that the glycosylic bond adopts an anti orientation (chi = -139.9(2)degrees), while the sugar moiety has an N conformation (C3'-endo; P = 4.3(1)degrees, tau(m) = 42.4(1)degrees).