2-isobutyrylamino-9-(5-O-benzoyl-3'-azido-2',3'-dideoxy-β-D-erythro-pentofuranosyl)-6-(2,4,6-triisopropylsulfonyl)-9H-purine

3'-azido-5'-O-tert-butyldimethylsilyl-N2-isobutyryl-2',3'-dideoxyguanosine

N-{9-[(2R,4S,5S)-4-Amino-5-(tert-butyl-dimethyl-silanyloxymethyl)-tetrahydro-furan-2-yl]-6-oxo-6,9-dihydro-1H-purin-2-yl}-isobutyramide

Diphenyl-carbamic acid 9-[(2R,4S,5S)-5-(tert-butyl-dimethyl-silanyloxymethyl)-4-(trityl-amino)-tetrahydro-furan-2-yl]-2-isobutyrylamino-9H-purin-6-yl ester

N-[9-((2R,4S,5R)-4-Amino-5-aminomethyl-tetrahydro-furan-2-yl)-6-oxo-6,9-dihydro-1H-purin-2-yl]-isobutyramide