The chemical synthesis of oligoribonucleotides VII. A comparison of condensing agents in the coupling of silylated ribonucleosides.

The t-butyldimethylsilyl group is shown to be an ideal protecting group for the 2T-hydroxyl function of ribonucleosides during the synthesis of ribonucleotides using any of nine commonly used condensing agents. The phosphite coupling procedure compares favorably with all of the widely used condensing agents and provides a most convenient route to the key intermediates in the "modified" triester strategy.