Synthesis of 2′-O-p-Nitrophenylethylsulfonyl-Ribonucleosides

Nucleotides Part LI. Synthesis and biological activities of (2′‐5′)adenylate trimer conjugates with 2′‐terminal 3′‐O(ω‐hydroxyalkyl) and 3′‐O‐(ω‐carboxyalkyl) spacers

“…1~ DMU the acid 62 (72%). After 2'-0-protection with the 2-(4-nitrophenyl)ethoxysulfonyl (npes) group [24] [25] It has also to be mentioned that conjugate 60 with a diethyleneglycol spacer could be dissolved in H,O and trimer 61 with a pentyl spacer in various buffers, whereas, however, conjugate 59 with a undecyl spacer was only soluble in DMSO and ternary mixtures of CH,Cl,/MeOH/H,O.…”

“…calc. for C,,HZ6N60, (434.6): C 52.53, H 6.03, N 19.34; found: C 52.31, H 6.15, N 18.88.3'-0-{5-~(9H-Fluoren-9-yImethoxy)carbonyl]pentyl}adenosine(24). As described for 20, with 19 (2.9 g, 2.3 mmol) and 80% AcOH/H,O (20 ml).…”

“…As described for 20, with 19 (2.9 g, 2.3 mmol) and 80% AcOH/H,O (20 ml). FC (silica gel (60 g), 4 x 16 cm; CH,CI, (200 ml), CH,CI,/MeOH 95: 5 (200 ml), 9: 1 (400 ml)) gave 0.99 g (78 YO) of24 as a foam which crystallized from H,O/EtOH 2: 1. Colourless crystals.…”

Facile and highly selective 5′-desilylation of multisilylated nucleosides

“…3,4 One useful feature of the TIPDS protecting group is that it can be partially cleaved at the 5Ј-position of 3Ј,5Ј-TIPDS protected ribofuranoses using 0.2 M HCl in dioxane-H 2 O (4 : 1) 13 or 1 M HCl in dioxane. 14 However, the cleavage of the 3Ј-end as well as full deprotection are often unavoidable under these conditions, so that the yields of expected 3Ј-silylation products are only moderate. 15- 17 Markiewicz also mentions that the selectivity of this cleavage can be enhanced when electron-withdrawing groups are present in the 2Ј-position of nucleosides.…”

Nucleotides. Part XLVII. Synthesis of 3′‐Deoxyadenylyl‐(2′–5′)‐3′‐deoxyadenylyl‐(2′–5′)‐3′‐O‐(2‐hydroxyethyl)adenosine and 3′‐Deoxyadenylyl‐(2′–5′)‐3′‐deoxyadenylyl‐(2′–5′)‐3′‐O‐{2‐[(cholest‐5‐en‐3β‐yloxy)carbonyloxy]ethyl}adenosine: A New Type of (2′–5′)Adenylate Trimer Conjugate

“…Selective monomethoxytritylation afforded derivative 12 then in 81 YO yield. The 2'-OH position was finally protected by the 2-(4-nitrophenyl)ethoxysulfonyl (npes) group [30] leading to 13 in 85 YO yield. The npes group was chosen in preference to the npeoc blocking group due to its greater stability under deacetylation conditions.…”