Replacement of Canonical DNA Nucleobases by Benzotriazole and 1,2,3‐Triazolo[4,5‐<i>d</i>]pyrimidine: Synthesis, Fluorescence, and Ambiguous Base Pairing

Abstract

Abstract The syntheses and the fluorescence properties of 7 H ‐3,6‐dihydro‐1,2,3‐triazolo[4,5‐ d ]pyrimidin‐7‐one 2′‐deoxy‐ β ‐ D ‐ribonucleosides (=2′‐deoxy‐8‐azainosine) 3 ( N 3 ), 15 ( N 2 ), and 16 ( N 1 ) as well as of 1,2,3‐benzotriazole 2′‐ O ‐methyl‐ β ‐ or ‐ α ‐ D ‐ribofuranosides 6 ( N 1 ) and 24 ( N 1 ) are described. Also the fluorescence properties of 1,2,3‐benzotriazole 2′‐deoxy‐ β ‐ D ‐ribofuranosides 4 ( N 1 ) and 5 ( N 2 ) are evaluated. From the nucleosides 3 – 6 , the phosphoramidites 19, 26a, 26b , and 28 are prepared and employed in solid‐phase oligonucleotide synthesis. In 12‐mer DNA duplexes, compound 3 shows similar ambiguous base‐pairing properties as 2′‐deoxyinosine ( 1 ), while the nucleosides 4 – 6 show strong pairing with each other and discriminate very little the four canonical DNA constituents.