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Helvetica Chimica Acta – Vol. 92 (2009)
128.72 (2d); 128.54 (4d); 128.14 (4d); 127.99 (2d); 127.40 (2d); 114.37 (s, Me2C); 113.47 (2d); 88.10 (s,
Ph2C); 55.37 (q, MeO); 35.88 (q, MeN); 34.20 (d, Me2CH); 27.37, 25.67 (2q, Me2C); 25.35 (s, Me2CSi);
20.40 (q, Me2CSi); 18.57, 18.53 (2q, Me2CH); ꢀ 3.30, ꢀ 3.34 (2q, Me2Si). HR-MALDI-MS: 892.4064
([M þ Na]þ, C50H59N5NaO7Siþ; calc. 892.4081).
Data of N6-Benzoyl-5’-O-[dimethyl(1,1,2-trimethylpropyl)silyl]-2’,3’-O-isopropylidene-8-{[(4-meth-
oxyphenyl)diphenylmethoxy]methyl}-1-methyladenosine (11). Colourless glass. Rf (cyclohexane/AcOEt
2 :1) 0.26. [a]2D5 ¼ ꢀ25.6 (c ¼ 1.3, CHCl3). UV (CHCl3): 241 (24340), 277 (11920), 305 (12000). IR
(ATR): 3058w, 3028w, 2956w, 2867w, 1645s, 1607m, 1578m, 1542m, 1509m, 1489w, 1463w, 1447m, 1416w,
1391m, 1372m, 1346w, 1307m, 1250s, 1213m, 1178m, 1155m, 1060s, 1032s, 1002w, 970m, 928w, 901w.
1H-NMR (300 MHz, CDCl3): see Table 3; additionally, 8.16 – 8.13 (m, 2 arom. H); 7.54 – 7.20 (m, 15 arom.
H); 6.78 – 6.75 (m, 2 arom. H); 3.78 (s, MeO); 3.71 (s, MeN); 1.61 (sept., J ¼ 6.9, Me2CH); 1.46, 1.33 (2s,
Me2C); 0.87 (d, J ¼ 6.9, Me2CH); 0.83 (s, Me2CSi); 0.05, 0.04 (2s, Me2Si). 13C-NMR (75 MHz, CDCl3):
see Table 4; additionally, 177.84 (s, C¼O); 158.79, 143.71, 143.64, 136.24, 134.85 (5s); 131.78 (d); 130.48
(2d); 129.78 (2d); 128.56, 128.54 (4d); 128.06 (2d); 127.97, 127.96 (4d); 127.12 (2d); 114.46 (s, Me2C);
113.33 (2d); 87.86 (s, Ph2C); 55.34 (q, MeO); 36.82 (q, MeN); 34.22 (d, Me2CH); 27.38, 25.73 (2q, Me2C);
25.35 (s, Me2CSi); 20.44 (q, Me2CSi); 18.63, 18.61 (2q, Me2CH); ꢀ 3.18, ꢀ 3.26 (2q, Me2Si). HR-
MALDI-MS: 892.4069 ([M þ Na]þ, C50H59N5NaO7Siþ; calc. 892.4081).
N6-Benzoyl-5’-O-[dimethyl(1,1,2-trimethylpropyl)silyl]-8-(hydroxymethyl)-2’,3’-O-isopropylidene-
N6-methyladenosine (12). A soln. of 10 (1.637 g, 1.88 mmol) in CH2Cl2 (10 ml) was treated with Et3SiH
(2.4 ml, 15.0 mmol) and Cl2CHCOOH (1.9 ml, 22.6 mmol), and stirred for 15 min at 258. The mixture was
neutralised with sat. aq. NaHCO3 soln., and the aq. layer was extracted with CH2Cl2. The combined org.
layers were dried (Na2SO4) and evaporated. FC (cyclohexane/AcOEt 2 :1 ! 1:1) gave 12 (884 mg,
79%). White solid. Rf (cyclohexane/AcOEt 2 :1) 0.24. M.p. 55 – 608. [a]2D5 ¼ ꢀ24.1 (c ¼ 0.75, CHCl3). UV
(CHCl3): 286 (15280). IR (ATR): 3375w, 3346w, 2956w, 2868w, 1671m, 1590s, 1575s, 1458m, 1447m,
1418w, 1372m, 1344m, 1321s, 1275m, 1251m, 1210m, 1155m, 1130m, 1079s, 1044s, 971w, 911w, 866m, 828s.
1H-NMR (400 MHz, CDCl3): see Table 3; additionally, 7.45 – 7.42 (m, 2 arom. H); 7.32 – 7.27 (m, 1 arom.
H); 7.20 – 7.16 (m, 2 arom. H); 3.78 (s, MeN); 3.52 (dd, J ¼ 6.4, 5.9, OH); 1.62, 1.38 (2s, Me2C); 1.61 (sept.,
J ¼ 6.9, Me2CH); 0.86 (d, J ¼ 6.9, Me2CH); 0.83 (s, Me2CSi); 0.05 (s, Me2Si). 13C-NMR (100 MHz,
CDCl3): see Table 4; additionally, 172.32 (s, C¼O); 136.34 (s); 130.75 (d); 128.71 (2d); 128.00 (2d);
115.00 (s, Me2C); 35.89 (q, MeN); 34.17 (d, Me2CH); 27.33, 25.49 (2q, Me2C); 25.56 (s, Me2CSi); 20.44,
20.40 (2q, Me2CSi); 18.54 (q, Me2CH); ꢀ 3.34 (q, Me2Si). HR-MALDI-MS: 598.3056 ([M þ H]þ,
C30H44N5O6Siþ; calc. 598.3061).
N6-Benzoyl-8-(chloromethyl)-5’-O-[dimethyl(1,1,2-trimethylpropyl)silyl]-2’,3’-O-isopropylidene-N6-
methyladenosine (13). A soln. of 12 (785 mg, 1.31 mmol) in CH2Cl2 (6.5 ml) was cooled to 08, treated with
EtNiPr2 (342 ml, 1.97 mmol) and MsCl (101 ml, 1.31 mmol), stirred at 258 for 18 h, treated with LiCl
(56 mg, 1.31 mmol), and stirred for 3 h. The mixture was diluted with CH2Cl2 and washed with H2O. The
combined org. layers were dried (Na2SO4) and evaporated. FC (cyclohexane/AcOEt 4 :1) gave 13
(755 mg, 94%). White solid. Rf (cyclohexane/AcOEt 4 :1) 0.36. M.p. 45 – 558. [a]2D5 ¼ ꢀ23.0 (c ¼ 0.7,
CHCl3). UV (CHCl3): 293 (15390). IR (ATR): 2957w, 2868w, 1673m, 1575s, 1461m, 1447m, 1417w,
1374m, 1350m, 1317s, 1277m, 1251m, 1211m, 1177w, 1154m, 1130m, 1080s, 1059s, 1043s, 1024m, 971w,
913w, 866m, 825s. 1H-NMR (400 MHz, CDCl3): see Table 3; additionally, 7.46 – 7.43 (m, 2 arom. H); 7.32 –
7.28 (m, 1 arom. H); 7.22 – 7.17 (m, 2 arom. H); 3.80 (s, MeN); 1.63, 1.40 (2s, Me2C); 1.58 (sept., J ¼ 6.9,
Me2CH); 0.84 (d, J ¼ 6.9, Me2CH); 0.80, 0.79 (2s, Me2CSi); ꢀ 0.01, ꢀ 0.02 (2s, Me2Si). 13C-NMR
(100 MHz, CDCl3): see Table 4; additionally, 172.42 (s, C¼O); 136.27 (s); 130.80 (d); 128.76 (2d); 128.01
(2d); 114.62 (s, Me2C); 35.87 (q, MeN); 34.22 (d, Me2CH); 27.38, 25.57 (2q, Me2C); 25.43 (s, Me2CSi);
20.43, 20.40 (2q, Me2CSi); 18.58, 18.57 (2q, Me2CH); ꢀ 3.35 (q, Me2Si). HR-MALDI-MS: 616.2706
([M þ H]þ, C30H43ClN5O5Siþ; calc. 616.2722).
5’-O-[Dimethyl(1,1,2-trimethylpropyl)silyl]-2’,3’-O-isopropylidene-N6-methyladenosine-8-methyl-
(81 ! 5’-S)-2’,3’-O-isopropylidene-5’-thiouridine (15). A soln. of 13 (684 mg, 1.11 mmol) and 14 [1]
(380 mg, 1.11 mmol) in dry degassed MeOH (3.5 ml) was cooled to 08, treated with a freshly prepared
1.27m soln. of MeONa in MeOH (3.5 ml, 4.44 mmol), and stirred at 258 for 19 h. The mixture was diluted
with sat. aq. NH4Cl soln. and H2O, and extracted four times with CH2Cl2. The combined org. layers were
dried (Na2SO4) and evaporated. FC (CH2Cl2/MeOH 95 :5) gave 15 (827 mg, 96%). White solid. Rf