244
Nair, Mickle, and Bera
was stirred for an additional 1h at ꢂ10ꢁC, then quenched with water and evaporated to
dryness. The residue was partitioned between saturated aqueous NaHCO3 (60 mL) and
CHCl3 (50 mL) and the aqueous part was further extracted with CHCl3 (50 mL). The
combined CHCl3 layers were dried over Na2SO4, evaporated to dryness and purified
1
over silica gel to give 10 (0.28 g, 78%) as a gum: H NMR (CDCl3) d 0.63 (m, 2H),
0.87 (m, 1H), 1.06 (m, 1H), 3.90 (m, 2H), 4.08–4.22 (m, 3H), 4.46 (dd, 1H), 7.42 (t,
2H), 7.55 (t, 1H), 8.02 (d, 2H); 13C NMR (CDCl3) d 3.78, 25.18, 60.01, 69.46, 72.74,
73.05, 123.49, 124.73, 128.23, 161.56; HRMS (FAB): (M þ H)þ calcd for C14H17O4
249.1126, found 249.1130.
4(S)-(6-Amino-9H-purin-9-yl)-3-spirocyclopropyltetrahydro-2(S)-furanmethanol
(11b) and 4(S)-(6-Amino-3H-purin-3-yl)-3-spirocyclopropyltetrahydro-2(S)-furan-
methanol (12b). To a suspension of 10 (0.15 g, 0.6 mmol), adenine (0.12g, 0.9 mmol),
Ph3P (0.24 g, 0.9 mmol) in dioxane (20 mL) was added DEAD (0.2 mL). After the
addition, the reaction mixture was stirred at room temperature for 2 days. The solvent
was then evaporated to dryness and the residue was purified over silica gel to give 11a
and 12a. To a solution of 11a in MeOH (12 mL) was added 1N NaOH (1 mL) and the
solution was stirred at room temperature for 1.5 h, then neutralized with 0.5 M HCl
and the solvent was evaporated to dryness. The residue was purified over silica gel to
give 11b (0.027 g, 17% from 10) as a white solid. Compound 12a was deprotected
following the same method to give 12b (0.22 g, 14% from 10) as a white solid.
1
Compound 11b: m.p: 180–181ꢁC; UV (MeOH) lmax 261 (13,800); H-NMR
(MeOH-d4) d 8.55 (s, 1H), 8.15 (s, 1H), 4.84 (s, 1H), 4.26 (m, 2H), 3.92 (m, 1H),
3.70 (dd, J ¼ 3.4, 12.2 Hz, 1H), 3.47 (dd, J ¼ 4.2, 12.2 Hz), 1.21 (m, 1H), 0.93 (m,
1H), 0.73 (m, 1H), 0.38 (m, 1H); 13C-NMR (MeOH-d4) d 157.2, 153.6, 150.7,
141.7, 119.3, 84.5, 73.7, 63.5, 62.1, 29.8, 14.3, 8.8; HRMS (FAB): (MþH)þ calcd
for C12H16N5O2 262.1304, found 262.1304.
Compound 12b: mp 244ꢁC; UV (MeOH) lmax 275 (12,600); 1H-NMR (d4-
MeOH): 8.95 (s, 1H), 7.85 (s, 1H), 5.12 (m, 1H), 4.31 (m, 2H), 4.94 (m, 1H), 3.78
(dd, J ¼ 3.2, 12.5 Hz), 3.46 (dd, J ¼ 3.3, 13.4 Hz), 1.32 (m, 1H), 1.04 (m, 1H), 0.79
(m, 1H), 0.46 (m, 1H); 13C-NMR (d4-MeOH): 156.5, 152.9, 150.9, 144.7, 120.5,
84.6, 73.7, 68.4, 61.3, 29.2, 14.9, 9.8. HRMS (FAB): (MþH)þ calcd for
C12H16N5O2 262.1304, found 262.1316.
5-O-Benzoyl-1,2-O-isopropylidene-3(R)-methyl-a-D-xylofuranose (13). To
a
solution of 5 (3.85 g, 13.3 mmol) in ethanol (150 mL) was added Pd=C (1.00 g).
The suspension was stirred under 25 psi of H2 for 24 h and filtered. The filtrate
was evaporated and the residue was purified over silica gel to give 13 (3.84 g, 99%)
1
as an oil: H NMR (CDCl3) d 1.15 (d, 3H), 1.35 (s, 3H), 1.54 (s, 3H), 2.04 (m,
1H), 4.11 (m, 1H), 4.38 (m, 1H), 4.58 (m, 2H), 5.85 (d, 1H), 7.44 (t, 2H), 7.57 (t,
1H), 8.03 (d, 2H); 13C NMR (CDCl3) d 9.35, 26.12, 26.31, 40.16, 64.30, 82.59,
105.05, 111.59, 128.36, 129.76, 133.10, 166.42; HRMS (FAB): (MþNa)þ calcd for
C16H20NaO5 315.1208, found 315.1212.
2(S)-(Benzoyloxymethyl)-3(S)-methyltetrahydrofuran-4(R)-ol (14). Hydrogen
chloride (0.03 g, 0.75 mmol) was bubbled through a solution of 13 (3.85 g,