Disaccharide nucleosides with 2'-O-(D-arabinofuranosyl), 2'-O-(L-arabinofur
anosyl), 2'-O-(D-ribopyranosyl), 2'-O-(D-erythrofuranosyl), and 2'-O-(5-azi
do-5-deoxy-D-ribofuranosyl) substituents were synthesized. These modified n
ucleosides were incorporated into oligonucleotides (see Table). Single subs
titution resulted in a DeltaT(m) of +0.5 to -1.4 degrees for DNA/RNA and a
DeltaT(m) of - 0.8 to -4.7 degrees for DNA/DNA duplexes. These disaccharide
nucleosides can be well accommodated in RNA/DNA duplexes, and the presence
of a NH2- C(5") group has a beneficial effect on duplex stability.