Two novel 5(20)-thia analogues of docetaxel have been synthesized from 10-deacetylbaccatin III ortaxine B and isotaxine B. The key step of these syntheses is the concomitant thietane ring formationand acetylation of the tertiary alcohol at C-4. Both compounds are less cytotoxic than docetaxelbut have divergent activity on microtubule disassembly.
