ABSTRACT
C-Nucleosides have C l ’ of their sugar moieties linked to different nitrogen-contain ing heterocycles through a carbon-carbon bond. Although TV-nucleosides which have a C l ’-N glycosidic link predominate in nature, there are many naturally occurring Gnucleosides which have a C l ’-C glycosidic link.1^ The first C-nucleoside isolated was pseudouridine (6 .1),5 many other members of this class of nucleoside have now been isolated from natural sources, such as showdomycin (6 .2),6 formycin (6.3),7 pyrazofurin (1.58)8 and oxazinomycin (6.4),9 or prepared synthetically such as tiazofurin (6.5) ,10 selenazofurin (6 .6 ),11 ethyl 3,5-dichloro-6-(P-D-ribofuranosyl) pyrazine-2-carboxylate (6.7)12 and 7 - (5-deoxy-5 ’-iodo-P-D-ribofuranosyl) thieno [3,4-^pyrimidin-4(3//)-one (6 .8 )13 (Fig. 6.1).
