C. Meier, C. Ducho, H. Jessen, D. Vukadinovic´-Tenter, J. Balzarini
FULL PAPER
2.40 mmol) and stirring at –20 °C for 10 min, a solution of dry
pyridine (364 mg, 4.60 mmol) in dry diethyl ether was added at the
same temperature over a period of 3 h. After completion of the
addition, the reaction mixture was allowed to warm to room tem-
perature and stirred for 2 h. It was kept at –20 °C overnight for
a complete precipitation of pyridinium chloride. Filtration under
nitrogen and concentrated of the filtrate under reduced pressure
afforded the phosphitylating agent (saligenyl chlorophosphite) as a
crude product to be directly used for the synthesis of the cycloSal
1.69 (s, 3 H, thymine-CH3), 2.05 (s, 3 H, acetyl-CH3), 2.06 (s, 3 H,
3
acetyl-CH3), 2.70 (t, JH,H = 7.3 Hz, 4 H, 2×9-H), 2.84 (t, 3JH,H
=
7.3 Hz, 4 H, 2×8-H), 4.24–4.35 (m, 4 H, 2×5Ј-H), 4.94–5.00 (m,
2 H, 2×4Ј-H), 5.34–5.58 (m, 4 H, 2×benzyl-H), 5.66 (s, 2 H, 11-
H), 5.67 (s, 2 H, 1×11-H), 6.00–6.04 (m, 2 H, 2×2Ј-H), 6.36 (ddd,
3
4
3JH,H = 6.0, JH,H = 1.6, JH,H = 1.6 Hz, 1 H, 3Ј-H), 6.42 (ddd,
3JH,H = 6.0, 3JH,H = 1.6, 4JH,H = 1.6 Hz, 1 H, 3Ј-H), 6.78 (dd, 3JH,H
= 2.6, JH,H = 1.6 Hz, 1 H, 1Ј-H), 6.80 (dd, JH,H = 2.6, JH,H
1.6 Hz, 1 H, 1Ј-H), 7.02 (d, JH,H = 8.5 Hz, 1 H, aryl-3-H), 7.05
4
3
4
=
3
3
phosphate triester 3d without further purification. The general syn- (d, JH,H = 8.5 Hz, 1 H, aryl 3-H), 7.15–7.26 (m, 63 H, 2×aryl 4-
thesis of cycloSal-d4T-monophosphates has been published be-
fore.[3,5,13] Diisopropylethylamine (DIPEA; 194 mg, 1.50 mmol)
was added to a solution of d4T 1 (224 mg, 1.00 mmol) in dry
CH3CN. The resulting solution was cooled to –20 °C and the chlo-
rophosphite (350 mg, 1.20 mmol) was added. The solution was al-
lowed to warm to room temperature, and stirring was continued
for 3 h. Subsequently, tert-butyl hydroperoxide (6 m in n-decane;
H, 2×aryl 6-H, 2×thymine 6-H), 11.34 (s, 2 H, 2×NH) ppm. 13C
NMR (101 MHz, [D6]DMSO): δ = 12.00 (thymine-CH3), 12.09
(thymine-CH3), 20.64 (2 × acetyl-CH3), 29.16 (2 × C-8), 34.59
2
2
(2×C-9), 68.38 (d, JC,P = 6.1 Hz, 2×benzyl-C), 68.52 (d, JC,P
=
3
6.1 Hz, 2×C-5Ј), 79.15 (2×C-11), 84.28 (d, JC,P = 8.0 Hz, 2×C-
4Ј), 89.35 (2×C-1Ј), 109.82 (2×thymine-C-5), 118.14 (d, JC,P
3
=
8.0 Hz, 2×aryl-C-3), 125.94 (aryl-C-6), 126.00 (aryl-C-6), 127.46
0.50 mL, 3.00 mmol) was added at –20 °C. After warming to room (2×C-2Ј), 127.97 (2×aryl-C-1), 129.78 (aryl-C-4), 129.96 (aryl-C-
temperature and stirring for 1 h, the solvent was removed under
reduced pressure. The resulting residue was purified by preparative
TLC [Chromatotron®; 1. ethyl acetate/MeOH (0.1% HOAc), 9:1;
2. CH2Cl2/MeOH gradient (0–5%)]. Lyophilisation yielded 277 mg
4), 132.96 (C-3Ј), 133.03 (C-3Ј), 135.82 (thymine-C-6), 135.86 (thy-
mine-C-6), 136.65 (2×aryl-C-5), 148.08 (d, 2JC,P = 7.1 Hz, 2×aryl-
C-2), 150.85 (thymine-C-2), 150.88 (thymine-C-2), 163.88 (thymine-
C-4), 163.90 (thymine-C-4), 169.44 (2 ×C-12), 171.22 (2 ×C-10)
(0.56 mmol, 56%) of a diastereomeric mixture (ratio 1.0:1.0) as a ppm. 31P NMR (202 MHz, [D6]DMSO): δ = –8.00, –8.07 ppm.
colourless foam. Rf = 0.47 (CH2Cl2/MeOH, 9:1). 1H NMR
(500 MHz, [D6]DMSO): δ = 1.59 (d, 4JH,H = 1.0 Hz, 3 H, thymine-
HRMS (ESI+): m/z = calcd. 559.1094 [M + Na+]; found 559.1113.
HPLC: tR = 14.0 min (method I); tR = 11.9 min (method II). UV/
Vis (water/CH3CN): λmax = 265 nm.
4
CH3), 1.62 (d, JH,H = 1.0 Hz, 3 H, thymine-CH3), 1.75–1.83 (m,
3
3
4 H, 2×9-H), 2.30 (t, JH,H = 7.4 Hz, 2 H, 10-H), 2.32 (t, JH,H
=
5-[2-(Pivaloyloxymethoxycarbonyl)ethyl]-cycloSal-d4T-monophos-
phate [5-(POM-Pr)-cycloSal-d4TMP] (4b): Under nitrogen,
1.53 mL of a solution of DIPEA in dry CH3CN (1:100; 94.7 μmol
of DIPEA) and 1.37 mL of a solution of chloromethyl pivalate in
dry CH3CN (1:100; 94.7 μmol of chloromethyl pivalate) were
added dropwise to a solution of 5-(2-carboxyethyl)-cycloSal-
d4TMP (5b; 40 mg, 86 μmol) in 10 mL of dry CH3CN at room
temperature. The reaction mixture was stirred at room temperature
for 9 d and the reaction monitored by TLC (CH2Cl2/MeOH, 9:1).
The solvent was removed in vacuo and the residue was purified
by preparative TLC [Chromatotron®; CH2Cl2/MeOH gradient (0–
3%)]. The isolated product was lyophilized. Yield: 23 mg (39 mmol,
45 %) of a colourless solid as a 1.0:0.8 mixture of two dia-
7.4 Hz, 2 H, 10-H), 2.54–2.66 (m, 4 H, 2×8-H), 3.57 (s, 3 H, 12-
H), 3.58 (s, 3 H, 12-H), 4.24–4.34 (m, 4 H, 2×5Ј-H), 4.97–4.93 (m,
3
2 H, 2×4Ј-H), 5.34 (dd, 2JH,H = 16.9, JH,P = 6.9 Hz, 1 H, benzyl-
2
3
H), 5.38 (dd, JH,H = 13.2, JH,P = 6.3 Hz, 1 H, benzyl-H), 5.44
2
3
2
(dd, JH,H = 16.4, JH,P = 5.7 Hz, 1 H, benzyl-H), 5.48 (dd, JH,H
= 14.5, JH,P = 6.3 Hz, 1 H, benzyl-H), 5.99–6.05 (m, 2 H, 2×2Ј-
3
H), 6.35–6.38 (m, 1 H, 3Ј-H), 6.78–6.82 (m, 2 H, 2×1Ј-H), 7.10–
7.28 (m, 8 H, 2×aryl 4-H 2×aryl 5-H, 2×aryl 6-H, 2×thymine 6-
H), 11.32 (s, 1 H, NH), 11.34 (s, 1 H, NH) ppm. 13C NMR
(101 MHz, [D6]DMSO): δ = 11.75 (thymine-CH3), 11.85 (thymine-
CH3), 24.56 (C-10), 24.59 (C-10), 27.89 (2×C-8), 32.64 (C-9), 32.66
(C-9), 68.19 (d, 2JC,P = 3.2 Hz, benzyl-C), 68.26 (d, 2JC,P = 3.5 Hz,
2
benzyl-C), 68.51 (d, 2J = 4.0 Hz, C-5Ј), 68.61 (d, JC,P = 4.5 Hz,
1
stereomers. Rf = 0.43 (CH2Cl2/MeOH, 9:1). H NMR (500 MHz,
C-5Ј), 84.10 (C-4Ј), 84.18 (C-4Ј), 89.11 (C-1Ј), 89.19 (C-1Ј), 109.64
(thymine-C-5), 109.69 (thymine-C-5), 124.18 (2×C-aryl), 127.38
(2×C-2Ј), 130.30 (C-aryl), 130.35 (C-aryl), 132.74 (C-3Ј), 132.81
(C-3Ј), 135.62 (C-aryl), 135.68 (C-aryl), 150.70 (2×C-2), 163.71
(2×thymine-C-4), 172.97 (2×C-11) ppm. 31P NMR (162 MHz,
[D6]DMSO): δ = –8.37, –8.51 ppm. HRMS (FAB): m/z = calcd.
493.1376 [M + H]; found 493.1377. HPLC: tR = 14.5 min (method
I); tR = 11.1, 11.2 min (method II). UV/Vis (water/CH3CN): λmax
= 267 nm.
[D6]DMSO): δ = 1.11 (s, 9 H, tBu), 1.12 (s, 9 H, tBu), 1.63 (s, 3 H,
3
thymine-CH3), 1.70 (s, 3 H, thymine-CH3), 2.71 (t, JH,H = 7.6 Hz,
3
4 H, 2×9-H), 2.84 (t, JH,H = 7.6 Hz, 4 H, 2×8-H), 4.25–4.37 (m,
4 H, 2×5Ј-H), 4.96–5.00 (m, 2 H, 2×4Ј-H), 5.33–5.48 (m, 4 H,
2×benzyl-H), 5.69 (s, 2 H, 11-H), 5.70 (s, 2 H, 11-H), 6.02–6.05
3
3
4
(m, 2 H, 2×2Ј-H), 6.36 (ddd, JH,H = 5.7, JH,H = 2.5, JH,H
=
=
=
3
3
4
2.5 Hz, 1 H, 3Ј-H), 6.42 (ddd, JH,H = 5.7, JH,H = 2.5, JH,H
3
2.5 Hz, 1 H, 3Ј-H), 6.79–6.82 (m, 2 H, 2×1Ј-H), 7.02 (d, JH,H
8.2 Hz, 1 H, aryl 3-H), 7.05 (d, JH,H = 8.2 Hz, 1 H, aryl 3-H),
3
5-[2-(Acetoxymethoxycarbonyl)ethyl]-cycloSal-d4T-monophosphate 7.16–7.25 (m, 6 H, 2 × aryl 4-H, 2 × aryl 6-H, 2 × thymine 6-H),
[(5-AM-Pr)-cycloSal-d4TMP] (4a): Under nitrogen, 2.7 mL of a
solution of DIPEA in dry CH3CN (1:100; 0.17 mmol of DIPEA)
and 1.7 mL of a solution of bromomethyl acetate in dry CH3CN
(1:100; 0.17 mmol of bromomethyl acetate) were added dropwise
to a solution of 5-(2-carboxyethyl)-cycloSal-d4TMP (5b; 70 mg,
0.15 mmol) in 22 mL of dry CH3CN at 10 °C. The reaction mixture
was stirred at 10 °C for 3 h and the reaction monitored by TLC
(CH2Cl2/MeOH, 9:1). The solvent was removed in vacuo and the
residue was purified by preparative TLC [Chromatotron®; CH2Cl2/
11.35 (s, 2 H, 2×NH) ppm. 13C NMR (101 MHz, [D6]DMSO): δ
= 12.02 (thymine-CH3), 12.10 (thymine-CH3), 26.61 (2×tBu-CH3),
29.16 (2×C-8), 34.52 (2×C-9), 38.33 (2×tBu-C), 68.41–68.52 (m,
3
2×C-5Ј, 2×benzyl-C), 79.48 (2×C-11), 84.29 (d, JC,P = 8.1 Hz,
C-4Ј), 84.53 (C-4Ј), 89.35 (2 × C-1Ј), 109.84 (2 × thymine-C-5),
3
118.06 (d, JC,P = 3.1 Hz, 2×aryl-C-3), 125.94 (aryl-C-6), 126.00
(aryl-C-6), 127.48 (C-2Ј), 127.51 (C-2Ј), 128.43 (2 × aryl-C-1),
129.77 (aryl-C-4), 129.86 (aryl-C-4), 132.95 (C-3Ј), 133.02 (C-3Ј),
135.86 (2×thymine-C-6), 136.64 (2×aryl-C-5), 147.41 (2×aryl-C-
MeOH gradient (0–3 %)]. The isolated product was lyophilized. 2), 150.67 (thymine-C-2), 150.85 (thymine-C-2), 163.89 (thymine-
Yield: 53 mg (99 μmol, 65%) of a colourless solid as a mixture of
two diastereomers in a 1:1 ratio. Rf = 0.36 (CH2Cl2/MeOH, 9:1).
C-4), 163.91 (thymine-C-4), 167.17 (C-12), 167.32 (C-12), 171.19
(C-10), 171.24 (C-10) ppm. 31P NMR (202 MHz, [D6]DMSO): δ
1H NMR (500 MHz, [D6]DMSO): δ = 1.62 (s, 3 H, thymine-CH3), = –8.01, –8.08 ppm. HRMS (ESI+): m/z = calcd. 601.1533 [M +
204
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Eur. J. Org. Chem. 2006, 197–206