Solid-Phase Synthesis of DNA and RNA 5'-O-Triphosphates Using cycloSal Chemistry

A chemical method for the synthesis of short strands of DNA and RNA 5'-O-triphosphates is described that makes use of the conventional coupling and oxidizing reagents that are readily available on standard DNA/RNA synthesizers. After automated solid-phase synthesis of oligonucleotides and 5'-O-detritylation, a novel cycloSal-phosphoramidite, 5-chloro-saligenyl-N,N-diisopropylphosphoramidite, was coupled to the 5'-hydroxyl group and the product oxidized. The resulting support-bonded 5'-cycloSal-oligonucleotide was reacted with pyrophosphate to yield 5'-O-triphosphorylated DNA/RNA oligonucleotides after cleavage from the support in high purity and excellent yields. The reaction sequence was adapted to be used completely on a standard automated oligonucleotide synthesizer. © 2016 by John Wiley & Sons, Inc.