1. Studies on the biologic activity of purine and pyrimidine analogs
2. Rapid and efficient stereocontrolled synthesis of C-3′-ethynyl ribo and xylonucleosides by organocerium additions to 3′-ketonucleosides
3. Diastereofacial Selective Addition of Ethynylcerium Reagent and Barton−McCombie Reaction as the Key Steps for the Synthesis of C-3‘-Ethynylribonucleosides and of C-3‘-Ethynyl-2‘-deoxyribonucleosides
4. 9-(3′-C-ethyl-β-d-ribo-furanosyl) adenine 3. 9-(3′-C-ethynyl-β-d-ribo-furanosyl) adenine 13 (0.37 g; 1.25 mmol) was hydrogenated overnight in methanol (73 mL) at 25°C and 1 bar, in the presence of palladium on charcoal (10%, 0.15 g). The catalyst was removed by filtration on Celite (2×6 cm, methanol). The solution was concentrated to 2 mL then acetonitrile (10 mL) was added. Evaporation of the solvents gave compound 3 quantitatively. Mp=193–194°C; UV(MeOH): λmax=214 nm; ε=14000 M−1 cm−1; λmax=262 nm; ε=13600 M−1 cm−1; IR (KBr) 3422, 3339, 2993, 1674 cm−1; [α]24d−63 (c=1; DMSO); 1H NMR (DMSO-d6) δ 8.35 (s; 1H; H2); 8.12 (s; 1H; H8); 7.39 (s; 1H; NH2); 5.96 (s; 1H; OH); 5.88 (d; JH′1H′2=7.9 Hz; 1H; H′1); 5.40 (s; 1H; OH); 4.60 (s; 1H; OH); 4.50 (d; JH′1H′2=7.9 Hz; 1H; H′2); 3.91 (m; 1H; H′4); 3.61 (m; 2H; H′5); 1.73 (q; J=7.5 Hz; 2H; CH2); 0.97 (t; J=7.5 Hz; 3H; CH3); 13C NMR (DMSO-d6) δ 156.2 (C6); 152.0 (C2); 149.0 (C4); 140.6 (C8); 119.5 (C5); 87.8 (C′4); 87.7 (C′1); 78.2 (C′3); 76.5 (C′2); 61.3 (C′5); 25.5 (CH2); 7.7 (CH3). Anal. calcd for C12H17N5O4 : C 48.81, H 5.76, N 23.73. Found: C 48.98, H 5.93, N 23.55.; SM (CI) 296 (MH+; 100).
5. 9-(3′-C-ethyl-β-d-xylo-furanosyl) adenine 6. Compound 6 was synthesized from 9-(3′-C-ethynyl-β-d-xylo-furanosyl) adenine 43 as described above for compound 3. Mp=206–208°C; IR (KBr) 3476, 3303, 2975, 1679 cm−1; 1H NMR (CD3OD) δ 8.37 (s; 1H; H2); 8.20 (s; 1H; H8); 5.96 (s; 1H; H′1); 4.81 (s; 1H; H′2); 4.03 (m; 1H; H′4); 3.93 (m; 2H; H′5); 1.83 (m; 1H; CH2); 1.62 (m; 1H; CH2); 1.02 (t; J=7.2 Hz; 3H; CH3); 13C RMN (DMSO-d6) δ 156.0 (C6); 152.2 (C2); 148.6 (C4); 139.8 (C8); 118.85 (C5); 90.41 (C′1); 86.47 (C′4); 80.9 (C′2); 80.5 (C′3); 60.2 (C′5); 24.5 (CH2); 7.8 (CH3); SM (CI; NH3) 296 (MH+; 40), 295 (M+; 63), 135 (BH+; 100).