Nucleosides and Nucleotides. Part 18. p-nitrobenzenesulfonyl nitroimidazole as a new condensing agent in the triester synthesis of oligonucleotides†

p-Nitrobenzenesulfonyl nitroimidazole (p-NBSNI) (5) has been shown to be an efficient and convenient condensing agent in the coupling of protected nucleotide fragments. Its utility has been demonstrated by a direct comparison with previously-described condensing agents in the synthesis of various di- and tetradeoxy-nucleotides.