NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
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The mixture was stirred until a homogenous solution was obtained. Finally,
1M CuSO4 solution (40 mol%) was added and the reaction mixture was
vigorously stirred at room temperature for 24 hours. When the reaction
was complete, the solvent was removed using a rotary evaporator, and the
compound was purified by silica gel chromatography using a methylene
chloride – methanol mixture (5!10%, v/v) as the eluent. Following the
chromatographic purification, products 3a–c were obtained in 74–97% yield.
Compound 3a:
1
White solid; Yield: 75%; H NMR (400 MHz, DMSO–d6) d: 0.05 (6H, d,
J ¼ 2.4 Hz, Si(CH3)2), 0.85 (9H, s, C(CH3)3), 2.13–2.23 (3H, m, H-2’A, H-
2’’B, H-2’B), 2.34 (1H, m, H-2’’A), 3.73 (2H, ddd, J ¼ 21.7/11.3/3.7 Hz, H-5’/
5’’A), 4.02 (1H, m, H-4’A), 4.07 (1H, m, H-4’B), 4.16 (1H, m, H-3’A), 4.26
(1H, m, H-3’B), 4.57 (2H, s, OCH2), 4.62 (2H, dd, J ¼ 14.2/4.2 Hz, H-5’/5’’B),
5.50 (1H, d, J ¼ 4.4 Hz, 3’-OH), 5.60 (1H, d, J ¼ 8.0 Hz, H-5B), 5.63 (1H, d,
J ¼ 8.0 Hz, H-5A), 6.09 (1H, dd, J ¼ 4.0/8.0 Hz, H-1’A), 6.14 (1H, t,
J ¼ 6.8 Hz, H-1’B), 7.58 (1H, d, J ¼ 8.4 Hz, H-6A), 7.74 (1H, d, J ¼ 8.0 Hz, H-
6B), 8.07 (1H, s, H-triazole), 11.32 (2H, s, NH); 13C NMR (125 MHz,
DMSO–d6) d: 162.98 (C4B), 162.96 (C4A), 150.34 (C2B), 150.30 (C2A),
143.64 (C4 triazole), 140.80 (C6B), 140.02 (C6A), 124.68 (C5 triazole), 101.71
(C5B), 102.05 (C5A), 84.41 (C1’B), 84.39 (C1’A), 84.21 (C4’B), 84.25 (C4’A),
78.55 (C3’A), 70.75 (C3’B), 63.12 (C5’A), 61.68 (OCH2), 51.30 (C5’B), 38.06
(C2’B), 36.74 (C2’A), 25.71 (C(CH3)3), 17.89 (C(CH3)3), -5.60 (CH3Si), ꢀ5.67
(CH3Si); HRMS (ESI–) calcd for C27H38N7O9Si [M–H]– 632.2500, found
632.2518, calcd for C27H39N7O9SiCl [M þ Cl]– 668.2267, found 668.2284.
Compound 3b:
1
White solid; Yield: 97%; H NMR (400 MHz, DMSO–d6) d: 0.05 (6H, d,
J ¼ 2.0 Hz, Si(CH3)2), 0.85 (9H, s, C(CH3)3), 1.79 (3H, d, J ¼ 0.8 Hz, 5-
CH3), 2.06–2.14 (2H, m, H-2’A, H-2’’B), 2.17 (1H, m, H-2’B), 2.32 (1H,
m, H-2’’A), 3.72 (2H, ddd, J ¼ 21.8/11.2/3.8 Hz, H-5’/5’’A), 4.01 (1H, m,
H-4’A), 4.06 (1H, m, H-4’B), 4.16 (1H, m, H-3’A), 4.27 (1H, m, H-3’B),
4.57 (2H, s, OCH2), 4.68–4.73 (2H, m, H-5’/5’’B), 5.49 (1H, d, J ¼ 4.4 Hz,
3’-OH), 5.59 (1H, d, J ¼ 8.4 Hz, H-5A), 6.09 (1H, dd, J ¼ 8.0/6.0 Hz, H-
1’A), 6.16 (1H, t, J ¼ 7.0 Hz, H-1’B), 7.34 (1H, d, J ¼ 0.8 Hz, H-6B), 7.74
(1H, d, J ¼ 8.0 Hz, H-6A), 8.08 (1H, s, H-triazole), 11.30 (1H, s, NH B),
11.33 (1H, s, NH A); 13C NMR (125 MHz, DMSO–d6) d: 163.66 (C4B),
163.02 (C4A), 150.41 (C2B), 150.35 (C2A), 143.70 (C4 triazole), 140.05
(C6A), 136.07 (C6B), 124.73 (C5 triazole), 109.86 (C5B), 101.76 (C5A),
84.41 (C1’A), 84.28 (C4’A), 84.03 (C1’B), 83.99 (C4’B), 78.61 (C3’A),
70.76 (C3’B), 63.17 (C5’A), 61.75 (OCH2), 51.24 (C5’B), 37.93 (C2’B),
36.75 (C2’A), 25.74 (C(CH3)3), 17.93 (C(CH3)3), 12.08 (5CH3B), ꢀ5.56
(CH3Si), ꢀ5.63 (CH3Si); HRMS (ESI–) calcd for C28H40N7O9Si [M–H]–
646.2657, found 646.2667.