Novel syntheses of (Z)-alkene and alkane base-modified nucleosides

The syntheses of 5-(Z)-(3-aminoallyl)- and 5-(3-aminopropyl)-substituted 2′-deoxyuridine and 2′-deoxycytidine are reported. These compounds were derived from the corresponding 5-propargylamine derivative. [Hobbs, F. W. J. Org. Chem. 1989, 52, 3420.] The catalyst we have employed for these reductions is a NiCl2/NaBH4 system, which we have found to be superior to the more conventional palladium-catalysts previously reported with similar compounds.