Effect of Imino Group of a Linker Arm at the C5 Position of a Pyrimidine Nucleoside on the Thermal Stabilities of DNA/DNA and DNA/RNA Duplexes

The modified ODN's bearing C5‐substituted 2′‐deoxyuridine derivative were synthesized by a post‐synthetic modification with an unsymmetrical triamine. The effect of the C5‐substituent on the duplex formation with complementary DNA or RNA differed with the position of an imino group in the linker‐arms.