Replacement of canonical DNA nucleobases by benzotriazole and 1,2,3-triazolo[4,5-d]pyrimidine: Synthesis, fluorescence, and ambiguous base pairing

Abstract

The syntheses and the fluorescence properties of 7H-3,6-dihydro-1,2,3-triazolo[4,5-d]pyrimidin-7-one 2'-deoxy-beta-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-beta- or -alpha-D-ribofuranosides 6 (N-1) and 24 (N-1) are described. Also the fluorescence properties of 1,2,3-benzotriazole 2'-deoxy-beta-D-riboluranosides 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.