We designed and synthesized a set of 2 '-deoxyribonucleoside 3 '-phosphoramidites derived from 5-phenylethynyluracil, 5-(pentyn-1-yl)cytosine, 7-(indol-3-yl)ethynyl-7-deazaadenine, and 7-isopropylethynyl-7-deazaguanine. These nucleoside phosphoramidites were successfully used for automated solid-phase synthesis of oligonucleotides containing one or several modifications, including fully modified sequences where every nucleobase was displaying a modification, and their hybridization was studied.
The phosphoramidite building blocks have potential for synthesis of hypermodified aptamers and other functional nucleic acid-based polymers, which sequence-specifically display amino acid-like hydrophobic substituents.