title: Diastereofacial Selective Addition of Ethynylcerium Reagent and Barton-McCombie Reaction as the Key Steps for the Synthesis of C-3'-Ethynylribonucleosides and of C-3'-Ethynyl-2'-deoxyribonucleosides.
abstract: We describe the preparation of 3'-alkynyluridine 4a and -adenosine 4b and of 3'-alkynyl-2'-deoxyuridine 16a and -adenosine 16b starting from the corresponding nucleosides. The desired stereochemistry of the C-3' tertiary alcohol was obtained by reaction of an ethynylcerium-lithium reagent on a 3'-ketonucleoside with the hydroxyl group at C-5' unprotected. The 2'-deoxygenation was performed by a Barton-McCombie reaction under appropriate conditions where the addition of tin hydride to the triple bond was suppressed. Evaluation of the anti-HIV activity of the C-3' modified nucleosides is reported.
authors.affiliation: Laboratoire de Chimie Organique Biologique URA 31 du CNRS, Faculté de Chimie, Université Louis Pasteur, 1 rue Blaise Pascal, 67008 Strasbourg Cedex, France.
authors.forename: Pierre M. J.
authors.initials: PM
authors.lastname: Jung
authors.forename: Alain
authors.initials: A
authors.lastname: Burger
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Biellmann