N-[3-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-3-O-[(methylthio)methyl]-β-D-erythro-pentofuranosyl]-4-[(2-phenoxyacetyl)amino]-7H-pyrrolo[2,3-d]pyrimidin-5-yl]-2-propyn-1-yl]-2,2,2-trifluoroacetamide

N-[3-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-4-[[2-[4-(1,1-dimethylethyl)phenoxy]acetyl]amino]-7H-pyrrolo[2,3-d]pyrimidin-5-yl]-2-propyn-1-yl]-2,2,2-trifluoroacetamide

N-[3-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-4-[[2-[4-(1-methylethyl)phenoxy]acetyl]amino]-7H-pyrrolo[2,3-d]pyrimidin-5-yl]-2-propyn-1-yl]-2,2,2-trifluoroacetamide

N-[3-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-4-[(2-phenoxyacetyl)amino]-7H-pyrrolo[2,3-d]pyrimidin-5-yl]-2-propyn-1-yl]-2,2,2-trifluoroacetamide

N-[3-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-4-[(E)-[(dimethylamino)methylene]amino]-7H-pyrrolo[2,3-d]pyrimidin-5-yl]-2-propyn-1-yl]-2,2,2-trifluoroacetamide

N-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-5-iodo-7H-pyrrolo[2,3-d]pyrimidin-4-yl]-2-[4-(1,1-dimethylethyl)phenoxy]acetamide

N-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-5-iodo-7H-pyrrolo[2,3-d]pyrimidin-4-yl]-2-[4-(1-methylethyl)phenoxy]acetamide

N-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-5-iodo-7H-pyrrolo[2,3-d]pyrimidin-4-yl]-2-phenoxyacetamide

N-[7-[2-Deoxy-5-O-[(1,1-dimethylethyl)diphenylsilyl]-β-D-erythro-pentofuranosyl]-5-iodo-7H-pyrrolo[2,3-d]pyrimidin-4-yl]benzamide

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-[2-[4-(1,1-dimethylethyl)phenoxy]acetyl]-3′-O-[(methylthio)methyl]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-[2-[4-(1-methylethyl)phenoxy]acetyl]-3′-O-[(methylthio)methyl]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-3′-O-[(methylthio)methyl]-N-(2-phenoxyacetyl)-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-[(dimethylamino)methylene]-3′-O-[(methylthio)methyl]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-[2-[4-(1,1-dimethylethyl)phenoxy]acetyl]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-[2-[4-(1-methylethyl)phenoxy]acetyl]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-(2-phenoxyacetyl)-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-N-[(dimethylamino)methylene]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-5-iodo-N-[2-[4-(1-methylethyl)phenoxy]acetyl]cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-5-iodo-N-(2-phenoxyacetyl)cytidine

2′-Deoxy-5′-O-[(1,1-dimethylethyl)diphenylsilyl]-3′-O-[(ethyldithio)methyl]-5-[3-[(2,2,2-trifluoroacetyl)amino]-1-propyn-1-yl]uridine