Nucleotides. Part LVII. . Synthesis of phosphoramidite building blocks of 2′‐amino‐2′‐deoxyribonucleosides: New compounds for oligonucleotide synthesis

The chemical synthesis of 2′‐amino‐2′‐deoxyribonucleosides of uracil, cytosine, adenine, and guanine, and their conversion into suitably protected 3′‐phosphoramidite building blocks 35 – 40 for oligonucleotide synthesis are described. The aglycone and the 2′‐amino functions were protected using the 2‐(4‐nitrophenyl)ethoxycarbonyl (npeoc) group. The synthesis of the 3′‐ O ‐succinyl (3′‐ O ‐(3‐carboxypropanoyl))‐substituted starting nucleoside 41 is described and its behavior examined in solution and on solid phase with regard to an anticipated migration during 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) deprotection. Oligonucleotides were prepared using the new building blocks, and their hybridization properties were studied by UV‐melting techniques.