Synthesis and Cytostatic and Antiviral Activities of 2 '-Deoxy-2 ',2 '-difluororibo- and 2 '-Deoxy-2 '-fluororibonucleosides Derived from 7-(Het)aryl-7-deazaadenines
Abstract
A series of sugar-modified derivatives of cytostatic 7-heteroaryl-7-deazaadenosines (2-deoxy-2-fluororibo- and 2-deoxy-2,2-difluororibonucleosides) bearing an aryl or heteroaryl group at position7 was prepared and screened for biological activity. The difluororibonucleosides were prepared by non- stereoselective glycosidation of 6-chloro-7-deazapurine with benzoyl-protected 2-deoxy-2,2-difluoro-D-erythro-pentofuranosyl-1-mesylate, followed by amination and aqueous Suzuki cross-couplings with (het)arylboronic acids.
The fluororibo derivatives were prepared by aqueous palladium-catalyzed cross-coupling reactions of the corresponding 7-iodo-7-deazaadenine 2-deoxy-2-fluororibonucleoside 20 with (het)arylboronic acids. The key intermediate 20 was prepared by a six-step sequence from the corresponding arabinonucleoside by selective protection of 3- and 5-hydroxy groups with acid-labile groups, followed by stereoselective SN2 fluorination and deprotection.
Some of the title nucleosides and 7-iodo-7-deazaadenine intermediates showed micromolar cytostatic or anti-HCV activity. The most active were 7-iodo and 7-ethynyl derivatives.
The corresponding 2-deoxy-2,2-difluororibonucleoside 5-O-triphosphates were found to be good substrates for bacterial DNA polymerases, but are inhibitors of human polymerase.