title: C-3'-Branched Thymidines as Precursors for the Selective Generation of C-3'-Nucleoside Radicals.
abstract: C-3'-nucleoside radicals can be generated via Norrish type I photocleavage of C-3'-acyl nucleoside derivatives. In monomer experiments employing C-3'-acylthymidine derivatives 2 and 3, a 1:1 mixture of isomers of the H-abstraction products was obtained when the photolysis was carried out in the presence of a hydrogen donor. Derivatives 2 were synthesized by an approach which involves the formation of a silyl-protected cyanohydrin, which is subsequently alkylated with organolithium reagents, followed by hydrolysis. Derivatives 3 could be obtained via a multistep synthesis starting from diol 7. Several different methods were attempted to oxidize the unprotected diol to the alpha-hydroxy aldehyde. Finally, a route was chosen which involves a protection-deprotection sequence followed by oxidation of the free primary alcohol. The resulting modified nucleosides should facilitate the study of C-3'-DNA radicals.
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
authors.forename: Steffi
authors.initials: S
authors.lastname: Körner
authors.forename: Amanda
authors.initials: A
authors.lastname: Bryant-Friedrich
authors.forename: Bernd
authors.initials: B
authors.lastname: Giese