Abstract 2-(Phenylthio) ethyl is here proposed for temporary masking the thymine residue in the synthesis of sugar modified thymidine derivatives. This protection has been devised as a 'two-stage'system. The 2-(phenylthio) ethyl residue can be easily and regiospecifically inserted at the N3-position of the pyrimidine by a Mitsunobu reaction with 2-(phenylthio) ethanol and is perfectly stable also to strongly basic conditions. This allowed us to ...
