Synthesis of 2′-O-p-Nitrophenylethylsulfonyl-Ribonucleosides

Abstract
The appropriate protection of the 2′-OH group in ribonucleosides is the crucial point of oligoribonucleotide synthesis. The use of the tetrahydropyranyl (1), 4-methoxytetrahydropyranyl (2), tert. butyldimethylsily1 (3) and o-nitrobenzyl group (4) respectively has its limitations in the acid sensitivity or the problems arising during the deprotection steps. A more stable blocking group is needed, which is stable towards acid and base treatment but can be cleaved selectively under different conditions.