Evaluation of oligonucleotides containing two novel 2 '-O-methyl modified nucleotide monomers: A 3 '-C-allyl and a 2 '-O,3 '-C-linked bicyclic derivative

The two ribo-configured nucleosides 1-(3-C-allyl-2-O-methyl-beta-D-ribopent ofuranosyl)thymine 3 and (1S,5R,6R,8R)-5-hydroxy-6-(hydroxymethyl 1-methoxy -8-(thymin-1 -yl)-2,7-dioxabicyclo[3.3.0]octane 6 have been transformed int o their corresponding phosphoramidites, 5 and 8 respectively, and used as b uilding blocks for the synthesis of modified oligonucleotides. The oligonuc leotides were shown to hybridize with decreased binding affinity towards co mplementary single stranded DNA and RNA.