In other studies, main efforts were focused on the synthesis of nucleoside spirosultams 173 from the corresponding cyanohydrins 174. These were subjected to mesylation to form sulfonates 175 (68-69% yield), followed by intramolecular cyclization according to Thorpe to obtain sultones 173 (60-74% yield). Subsequently, O-desilylation was carried out to produce derivatives 176 (Scheme 30).