Double Protection of the Heterocyclic Base of Xanthosine and 2′-Deoxyxanthosine

Reaction of O-protected xanthosines with p-nitrophenyl ethanol under Mitsunobu conditions yields the doubly alkylated O2,O6- and N1-,O2-derivatives. Deoxyxanthosine protected on both oxygens with a 2-(4-nitrophenyl)-ethyl group was synthesized starting from deoxyguanosine. Both protecting groups can be eliminated with DBU in pyridine.