Solid‐Phase Synthesis of DNA and RNA 5′‐<i>O</i>‐Triphosphates Using <i>cyclo</i>Sal Chemistry

AbstractA 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 &amp; Sons, Inc.