title: Synthesis and anti-HIV evaluation of 2',3'-dideoxy imidazo- and nu-triazolo[4,5-d]pyridazine nucleosides.
abstract: The syntheses of the 2'-deoxy and 2',3'-dideoxynucleosides of 2,8-diaza-3-deazainosine and the 2',3'-dideoxynucleoside of 2-aza-3-deazainosine were achieved and the pathways leading to these novel nucleosides are described. The preparation of the 2',3'-dideoxynucleoside (1) of 2-aza-3-deazainosine involved deoxygenation of the 2'-deoxy-3'-imidazolide intermediate with n-Bu3SnH and AlBN. The latter nucleoside was synthesized from the known 2'-deoxy derivative of 2-aza-3-deazainosine. The three-step synthesis of 1 from the 2'-deoxy analogue was accomplished in 40% overall yield. Rather than synthesize the corresponding 2',3'-dideoxynucleoside (2) of 2,8-diaza-3-deazainosine in the same manner, i.e. deoxygenation of the 2'-deoxynucleoside, a more cost-effective route was chosen. This pathway involved reductive cleavage of the 5'-protected, 2',3'-thiocarbonate derivative to furnish a mixture of the 2'- and 3'-deoxy isomers. This mixture was not separated, but was deoxygenated by the aforementioned imidazolide method. Using this methodology, 2 was prepared in 23% overall yield from 2,8-diaza-3-deazainosine. Nucleosides 1 and 2 were evaluated for antiretroviral activity and were found to be inactive.
authors.affiliation: Department of Biomedical Sciences, University of Rhode Island, Kingston 02881-0809, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Bussolari
authors.forename: R P
authors.initials: RP
authors.lastname: Panzica
mesh_terms: D019380:Anti-HIV Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002478:Cells, Cultured; D016049:Didanosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests
chemical_list: C403504:2',3'-dideoxy-2,8-diaza-3-deazainosine; C403505:2-aza-3-deaza-2',3'-dideoxyinosine; D019380:Anti-HIV Agents; D016049:Didanosine