[4'-Branched nucleosides. I. Synthesis of 3'-deoxy-3'-amino-4'-hydroxymethylnucleosides].

The condensation of 1, 2-di-O-acetyl-3-azido-3-deoxy-4-benzoyloxymethyl-1-5-O-benzoyl-bet a-D-ribofuranose with trimethylsilyl derivatives of N6-benzoyladenine, N4-acetylcytosine and uracil in the presence of stannic chloride led to the corresponding nucleosides. After deprotection with methanolic ammonia the azidonucleosides were reduced with PPh3 into 3'-amino-3'-deoxy-4'-hydroxymethynucleosides.