7-Iodo-2’,3’-dideoxy-7-deazaadenosine (7-I-7-Deaza-ddA) 

7-Iodo-2’,3’-dideoxy-7-deazaguanosine (7-I-7-Deaza-ddG) 

2’,3’-Dideoxy-5-iodouridine (5-I-ddU)

2’,3’-Dideoxy-5-iodocytidine (5-I-ddC)