Mitsunobu reactions of nucleoside analogs using ... - UC Davis

3156 E. A. Véliz, P. A. Beal / Tetrahedron Letters 47 (2006) 3153–3156
681.0070, obsd 681.0062. 6-Bromo-2-(N-allyl)acetamido-
(2,3,5-tri-O-acetyl-b-D-ribofuranosyl)purine.
1 H NMR
(CDCl 3 , 500 MHz): d (ppm) 8.23 (s, 1H), 6.11 (d, J =
4.5 Hz, 1H), 5.86 (app. t, J = 5.0 Hz, 1H), 5.50 (app. t,
J = 5.0 Hz, 1H), 5.17 (dq, J = 17, 1.5 Hz, 1H), 5.08 (dq,
J = 10, 1.5 Hz, 1H), 4.75 (app. d, J = 5.5 Hz, 2H), 4.48–
4.45 (m, 1H), 4.40 (dd, J = 12.5, 3.5 Hz, 1H), 4.34 (dd,
J = 12.5, 4.5 Hz, 1H), 2.48 (s, 3H), 2.14 (s, 3H), 2.11 (s,
3H), 2.09 (s, 3H). 13 C NMR (CDCl 3 , 125 MHz): d (ppm)
171.6, 170.1, 169.5, 169.2, 155.2, 150.5, 143.1, 142.8, 133.2,
131.5, 116.8, 86.9, 80.1, 73.1, 70.0, 62.7, 48.8, 25.5, 20.7,
20.4, 20.3. HRCIMS: calcd for C 21 H 25 BrN 5 O 8 (M+H) +
554.0887, obsd 554.0885. 6-Bromo-2-(N-p-trifluoromethyl-
benzyl)acetamido-(2,3,5-tri-O-acetyl-b-D-ribofuranosyl)-
purine. 1 H NMR (CDCl 3 , 500 MHz): d ppm) 8.22 (s, 1H),
7.52 (d, J = 8.5 Hz, 2H), 7.46 (d, J = 7.5 Hz, 2H), 6.06 (d,
J = 4.0 Hz, 1H), 5.82 (app. t, J = 5.0 Hz, 1H), 5.41–5.39
(m, 2H), 4.45–4.42 (m, 1H), 4.30 (dd, J = 12.5, 3.0 Hz,
1H), 4.24 (dd, J = 12.5, 4.5 Hz, 1H), 2.56 (s, 3H), 2.14 (s,
3H), 2.09 (s, 3H), 2.05 (s, 3H).
13 C NMR (CDCl 3 ,
125 MHz): d (ppm) 172.0, 170.1, 169.4, 169.1, 155.0, 150.5,
143.3, 143.0, 141.9, 131.7, 129.3 (q, 2 J = 31.75 Hz), 127.9,
124.1 (q, J = 270.1 Hz), 125.3 (q, 3 J = 3.75 Hz), 86.9, 79.9,
73.0, 69.9, 62.6, 49.4, 25.6, 20.6, 20.4, 20.2. HRCIMS:
calcd for C 26 H 26 BrF 3 N 5 O 8 (M+H) + 672.0918, obsd
672.0955.