文摘
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2'-Deoxy-C-aryl-nucleosides have found increasing importance in studying DNA-DNA and DNA-protein interactions, as unnatural DNA-base pairs, and as oligonucleotide based fluorophores. Access tothe required C-aryl-nucleosides is provided by several glycosylation methods. Though useful in manycases, these methods often have drawbacks such as low yields or low economic efficiency. The necessityfor intensive optimization of the reaction conditions and/or the use of hazardous and toxic reagents canrender C-glycosylation reactions cumbersome. Herein we describe a robust and highly efficientC-glycosylation method. It is shown that aryl cuprates of the Normant-type reliably react with Hoffer'schlorosugar to deliver C-aryl-nucleosides in up to 93% yield. This method may substitute for the previouslyemployed coupling with organocadmium or -zinc species. Peculiar reactivities are reported forC-glycosylation of Gilman-type aryl cuprates which required substantial arene-specific optimization.Interestingly, the glycosylation of Gilman cuprates was found to provide access not only to C-aryl-nucleosides but also to O-aryl-glycosides. The reactions of Gilman cuprates with Hoffer's chlorosugar 1in the presence of oxygen provided the coresponding O-aryl-2'-deoxyribosides in up to 87% yield withoutconcomitant C-glycosylation.
