Synthesis of Oligonucleotides Carrying Inter-nucleotide N-(Benzoazole)-phosphoramide Moieties

In this work, we present new oligonucleotide derivatives containing inter-nucleotide N-benzimidazole, N-benzoxazole, N-benzothiazole, and 1,3-dimethyl-N-benzimidazole (benzoazoles) phosphoramide groups. These modifications were introduced via the Staudinger reaction with appropriate azides during standard automated solid-phase oligonucleotide synthesis. The principal structural difference between the new azido modifiers and those already known is that they are bulk heterocyclic structures, similar to purine nucleoside bases. Modified oligonucleotides with one and two modifications at different positions and multiple modified heteronucleotide sequences were obtained with high yields. The possibility of multiple modifications in the process of automatic DNA synthesis is fundamental and critical for further application of our oligonucleotide derivatives. Initial studies on the properties of new oligonucleotides were carried out. The stability of the oligodeoxyribonucleotide duplex containing phosphoramide groups of N-benzoazoles with complementary DNA or RNA is slightly lower than that of native complexes.