N-(Pyren-1-ylmethyl)-(3R,4R)-4-(hydroxymethyl)pyrrolidin-3-ol was synthesised from (3R,4R)-4-(hydroxymethyl)pyrrolidin-3-ol and (3R,4S)-4-[(1S)-1,2-dihydroxyethyl]pyrrolidin-3-ol using alkylation with 1-(chloromethyl)pyrene or reductive amination with pyrene-1-carbaldehyde and NaCNBH3. The incorporation of N-(pyren-1-ylmethyl)azasugar moiety into oligodeoxynucleotides (ODN) as a bulge to form an intercalating nucleic acid (INA) induced a slight destabilization of INA–DNA duplex, whereas the INA–RNA duplex was strongly destabilized and 9 °C difference per modification in thermal stability between INA–DNA over INA–RNA duplexes was observed. The stabilization of a DNA three way junction (TWJ) was improved when the intercalator moiety was inserted into the junction region as a bulge.
