A series of 7-phenylsulfanyl- or 7-(2-thienyl)sulfanyl-7-deazapurine bases bearing diverse substituents at the position 6 was prepared through C-H sulfenylation of 6-chloro-7-deazapurine followed by cross-couplings or nucleophilic substitutions. The corresponding ribonucleosides (as thia-analogues of known nucleoside cytostatics) were prepared by glycosylation of 6-chloro-7-arylsulfanyl-7-deazapurines followed by the same transformations at the position 6. The 7-thienylsulfanyl-7-deazapurine bases 2b-2h exerted micromolar cytostatic activities, whereas the nucleosides did not show significant biological effects.