Studies on the Formation of the Internucleotidic Bond in RNA Synthesis Using Dialkylamino Phosphoroamidites

2-(4-Tolylsulfonyl)ethoxymethyl (TEM)-a new 2'-OH protecting group for solid-supported RNA synthesis

The 2-(4-tolylsulfonyl)ethoxymethyl (TEM) as a new 2'-OH protecting group is reported for solid-supported RNA synthesis using phosphoramidite chemistry. The usefulness of the 2'-O-TEM group is exemplified by the synthesis of 12 different oligo-RNAs of various sizes (14-38 nucleotides long). The stepwise coupling yield varied from 97-99% with an optimized coupling time of 120 s. The synthesis of all four pure phosphoramidite building blocks is also described. Two new reliable parameters, delta(C2')-delta(C3') and delta(H2')-delta(H3'), have been suggested for the characterization of isomeric 2'-O-TEM and 3'-O-TEM as well as other isomeric mono 2'/3'-protected ribonucleoside derivatives. The most striking feature of this strategy is that the crude RNA prepared using our 2'-O-TEM strategy is sufficiently pure (>90%) for molecular biology research without any additional purification step, thereby making oligo-RNAs easily available at a relatively low cost, saving both time and lab resources.

2-Diphenylmethylsilylethyl (DPSE): a versatile protecting group for oligodeoxyribonucleotide synthesis

2-Diphenylmethylsilylethyl (DPSE) is a new protecting group for the internucleotidic bonds in the solid-support and solution-phase synthesis of oligodeoxyribonucleotides by the phosphoramidite approach. This group is stable under acidic conditions and can be removed by a beta-fragmentation mechanism under mild conditions using aqueous NH4OH. Alternatively, this group can also be removed using tetrafluorosilane in acetonitrile.