© 2008 Oxford University Press
This article appears in the following Nucleic Acid Symposium Series issue: Joint Symposium of the 18th International Roundtable on Nucleosides, Nucleotides and Nucleic Acids and the 35th International Symposium on Nucleic Acids Chemistry [View the issue table of contents]
The acetal levulinyl ester (ALE) group for the 2'-hydroxyl protection of ribonucleosides and the synthesis of oligoribonucleotides
1Department of Chemistry, McGill University, Montreal, QC, Canada H3A 2K6
*Corresponding Author. masad.damha{at}mcgill.ca
Abstract
A novel 2'-O-ALE (Acetal Levulinyl Ester) uridine phosphoramidite derivative has been efficiently prepared and used for the solid-phase synthesis of a chimeric oligonucleotide strand, 5'-rU11-dT-3'. The average coupling yield of the phosphoramidite was comparable to one obtained with a 2'-TBDMS rU phosphoramidite reagent. Upon completion of the RNA chain assembly, the cyanoethyl phosphate protecting groups were removed using a solution of triethylamine in acetonitrile (2:3 v/v). The 2'-O-ALE protecting groups were cleaved under hydrazinolysis conditions. Finally, the RNA oligonucleotide was released from the Q-CPG support when treated with 1 molar TBAF in THF. When the TBAF step was carried out prior to hydrazinolysis, an oligonucleotide with its intact 2'-OALE groups was obtained.