Synthesis of certain 4'-substituted nucleosides.

We have developed general methods for the synthesis of 4'-fluoro- and 4'-methoxynucleosides by addition of iodinemonofluoride or iodine and methanol across the double bond of suitably protected 4',5'-unsaturated pyrimidine and purine nucleosides. The structures of these adducts have been determined by a combination of chemical, spectroscopic, and electrophoretic methods. The 4'-methoxy- and the uridine analogs of nucleocidin have been synthesized from the corresponding 4'-fluorouridine and 4'-methoxyadenosine derivatives.