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

Article abstract of DOI:10.1002/hlca.200590052

The syntheses and the fluorescence properties of 7H-3,6-dihydro-1,2,3- triazolo[4,5-d]pyrimidin-7-one 2′-deoxy-β-D-ribonucleosides (=2′-deoxy-8-azainosine) 3 (N³), 15 (N²), and 16 (N¹) as well as of 1,2,3-benzotriazole 2′-O-methyl-β- or -α-D-ribofuranosides 6 (N¹) and 24 (N¹) are described. Also the fluorescence properties of 1,2,3-benzotriazole 2′-deoxy-β-D-ribofuranosides 4 (N¹) and 5 (N²) 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.