A. Galeone et al. / Tetrahedron 58 (2002) 363±368
367
1.54 mmol) in CH3OH (15.0 mL), ®nely powdered K2CO3
(844 mg, 6.04 mmol) was added and the mixture stirred at
room temperature for 20 min. The reaction was quenched by
addition of aqueous 1 M KHSO4 (7.0 mL) and dried under
reduced pressure. The residue was puri®ed on a silica gel
column eluted with increasing amount of CH3OH in
CHCl3.The fractions eluted with 30% of CH3OH furnished
907 mg of 10 (97% yield) as yellow oil. IR nmax (CHCl3)
linear gradient from 0 to 30% in 45 min of CH3CNin TEAA
buffer (0.1 M, pH 7.0). Appropriate fractions were evapo-
rated and excess of TEAA removed by C18 reversed phase
HPLC column using a linear gradient from 0 to 30% in
35 min of CH3CNaqueous to give 166 mg of 12 (80%
yield) as a triethylammonium salt. IR nmax (liquid ®lm)
3020, 1670, 1598, 1506, 1202 cm21
;
1H N MRdH
(500 MHz, D2O) 8.31 (1H, s, H-2 or H-8), 7.98 (1H, s,
H-8 or H-2), 7.33±6.95 (5H, m, PhS), 4.99 (1H, m, H-10),
4.45 (1H, m, H-20), 4.10 (1H, m, H-30), 4.08 (2H, t,
J7.2 Hz, CH2N), 3.91±3.81 (4H, m, H-60a, H-60b,
CH2O), 2.30 (2H, m, H-40, H-50a), 1.70 (1H, m, H-50b),
1.62 and 1.48 (2H each, m's, alkyl chain methylene
protons); 13C N MRdC (125 MHz, CD3OD) 158.0, 148.2,
147.5, 142.5, 134.2, 133.0, 130.3, 127.5, 125.0, 76.2, 74.8,
67.5, 66.4, 62.0, 45.6, 44.7, 28.8, 28.6, 28.0; HRMS
(FAB2): [M2H]2, found 589.0948. C21H27N4O10P2S
requires 589,0923.
;
3019, 1682, 1607, 1498, 1394 cm21 1H N MRdH
(500 MHz, CD3OD) 8.32 (1H, s, H-2 or H-8), 8.21 (1H, s,
H-8 or H-2), 7.20±6.88 (10H, m, PhNH), 5.09 (1H, m,
H-20), 4.93 (1H, m, H-30), 4.71 (1H, m, H-10), 4.33 (2H, t,
J7.2 Hz, CH2N), 4.25 (2H, m, H-60a, H-60b), 3.60 (2H, t,
J6.1 Hz, CH2O), 2.56 (1H, m, H-40), 2.31 (2H, m, H-50a,
H-50b), 2.07 and 1.55 (2H each, m's, alkyl chain methylene
protons), 1.52 and 1.30 (3H each, s's, isopropylidene methyl
protons); 13C N MRdC (125 MHz, CD3OD) 157.5, 147.5,
147.0, 140.3, 136.1, 130.0, 126.4, 122.5, 117.6, 115.2,
85.0, 82.3, 67.0, 65.1, 62.5, 47.5, 44.3, 31.8, 29.8, 27.6,
27.1, 23.5; HRMS (FAB1): MH1, found 609.2573.
C30H38N6O6P requires 609.2590.
4.2.10. 1-[(1R,2S,3R,4R)-2,3-(Diacetoxy)-4-[[(dianilino-
phosphoryl)oxy]methyl]cyclopentyl]-9-[4-O-[bis(phenyl-
thio)phosphoryl]butyl]hypoxanthine (13). Compound 12
(28 mg, 0.40 mmol) was treated with 1.0 mL of Ac2O/
pyridine solution 2:3 (v/v). After 6 h at room temperature,
the dried mixture was lyophilized thus giving 30 mg of 13
(95% yield) as a triethylammonium salt. IR nma1x (liquid
®lm) 3034, 1710, 1620, 1518, 1240, 1105 cm21; H N MR
dH (500 MHz, CD3OD), 8.40 (1H, s, H-2), 8.08 (1H, s, H-8),
7.60±7.13 (5H, m, PhS), 5.71 (1H, br. t, H-20), 5.45 (1H, br.
t, H-30), 5.18 (1H, m, H-10), 4.22±4.12 (4H, m, CH2N,
H-60a, H-60b), 4.02 (2H, m, CH2O), 2.60, (1H, m, H-40),
2.40 (1H, m, H-50a), 2.18 (1H, m, H-50b), 2.15, 2.01 (3H
each, each s, CH3), 1.88 and 1.65 (2H each, m's, alkyl chain
methylene protons); 13C N MRdC (125 MHz, CD3OD)
172.4, 172.5, 158.0, 148.9, 147.9, 142.5, 133.5, 133.1,
129.8, 127.7, 124.3, 76.0, 74.3, 67.5, 66.1, 62.3, 45.0,
43.1, 29.5, 28.2, 28.0, 20.2, 20.1; 31P N MRdP (162 MHz,
D2O, decoupled with 1H) 20.84, 4.49; HRMS (FAB2):
[M2H]2, found 673.1112. C25H31N4O12P2S requires
673.1134.
4.2.8. 1-[(1R,2S,3R,4R)-2,3-(Isopropylidenedioxy)-4-[[(di-
anilinophosphoryl)oxy]methyl]cyclopentyl]-9-[4-O-[bis
(phenylthio)phosphoryl]butyl]hypoxanthine (11). To a
solution of 10 (900 mg, 1.48 mmol) in dry pyridine
(9.0 mL) S,S-diphenylphosphorodithioate (674 mg, 1.77
mmol) (cyclohexylammonium salt) and TPSCl (1.21 g,
4.00 mmol) were added and the reaction stirred for 8 h at
room temperature under N2 atmosphere. The mixture was
dried under reduced pressure and the residue puri®ed on a
silica gel column eluted with increasing amount of CH3OH
in CHCl3. The fractions eluted with 5% of CH3OH furnished
1.03 g of 11 (80% yield) as yellow oil. IR nmax (CHCl3)
2989, 1685, 1602, 1498, 1217 cm21; 1H dH (500 MHz,
CDCl3) 7.90 (1H, s, H-2 or H-8), 7.78 (1H, s, H-8 or
H-2), 7.51±7.30 (10H, m, PhS), 7.13±6.80 (10H, m,
PhNH), 6.55, 6.40 (1H each, each d, J10.2 Hz, NH),
5.09 (1H, m, H-20), 4.81 (1H, m, H-30), 4.52 (1H, m,
H-10), 4.28 (2H, m, H-60a, H-60b), 4.23 (2H, m, CH2O),
4.06 (2H, t, J7.2 Hz, CH2N), 2.56 (2H, m, H-50a, H-40),
2.50 (1H, m, H-50b), 1.85 and 1.65 (2H each, m's, alkyl
chain methylene protons), 1.49 and 1.22 (3H each, s's,
isopropylidene methyl protons); 13C N MRdC (125 MHz,
CDCl3) 156.9, 147.9, 147.0, 140.5, 140.0, 135.5, 129.9,
129.7, 129.4, 126.5, 126.4, 121.8, 118.3, 113.4, 83.6, 82.2,
67.2, 66.5, 66.2, 45.8, 43.6, 32.6, 28.0, 27.3, 26.6, 25.5;
HRMS (FAB1): MH1, found 873.2436. C42H47N6O7P2S2
requires 873.2423.
4.2.11. Compound 14. A solution of 13 (22 mg, 28.4 mmol)
in pyridine (24.0 mL) was slowly added over 15 h, using a
syringe pump, to a mixture of I2 (150 mg, 591 mmol) and
Ê
dried 3 A molecular sieves (1.5 g) in pyridine (24.0 mL) at
room temperature in the dark. After ®ltering and washing
with H2O, the combined ®ltrate and washings were evapo-
rated to dryness. The residue was dissolved in TEAA buffer
(1 M, pH 7.0, 3.0 mL), and puri®ed by a C18 reversed phase
HPLC column using a linear gradient from 0 to 30% in
45 min of CH3CNin TEAA buffer (0.1 M, pH 7.0). Appro-
priate fractions were evaporated and excess of TEAA
removed by C18 reversed phase HPLC column using a linear
gradient from 0 to 30% in 35 min of CH3CNaqueous to give
14 (triethylammonium salt), 15 mg (80% yield). IR nmax
(liquid ®lm) 3015, 1734, 1698, 1508, 1245, 1100,
4.2.9. 1-[(1R,2S,3R,4R)-2,3-(Dihydroxy)-4-[[(dianilino-
phosphoryl)oxy]methyl]cyclopentyl]-9-[4-O-[bis(phenyl-
thio)phosphoryl]butyl]hypoxanthine (12). A mixture of
11 (262 mg, 0.30 mmol) and isoamyl nitrite (606 mL,
4.50 mmol) in pyridine/AcOH/Ac2O (2:1:1, v/v 9.0 mL)
was stirred at room temperature for 8 h. The reaction
mixture was evaporated (at ,508C) and, successively,
dissolved in a mixture of H3PO2 (306 mL, 6.00 mmol),
Et3N(417 mL, 3.00 mmol) and pyridine (7.5 mL) and the
resulting solution was stirred at room temperature for 11 h.
After the mixture was evaporated (at ,508 C) and the resi-
due dissolved in TEAA buffer (0.1 M, pH 7.0). The solution
was puri®ed by a C18 reversed phase HPLC column using a
1
1085 cm21; H N MRdH (500 MHz, D2O), 8.53 (1H, s,
H-2 or H-8), 8.24 (1H, s, H-8 or H-2), 5.67 (1H, m, H-20),
5.45 (1H, m, H-30), 5.23 (1H, m, H-10), 4.37 (2H, t,
J7.2 Hz, CH2N), 4.30 (2H, m, H-60a, H-60b) 4.12 (2H, t,
CH2O, J6.3 Hz), 2.62 (1H, m, H-50a), 2.45 (1H, m, H-40),
2.19 (1H, m, H-50b), 2.07 and 1.65 (2H each, m's, alkyl
chain methylene protons), 2.10 and 1.98 (3H each, s's,