Journal of Medicinal Chemistry
Article
6-Chloro-7-(2-tosyloxyethyl)purine (14). A mixture of 6-chlor-
opurine (1) (500 mg, 3.24 mmol), ethylene di(p-toluenesulfonate)
(1.6 g, 4.21 mmol), and NaH (60% dispersed in oil, 142 mg, 3.56
mmol) in anhydrous DMF (15 mL) was reacted according to the
general alkylation procedure to give 14 (109 mg, 19%) and the
corresponding N9-isomer 14a (466 mg, 41%) as white solids.
column (3 μm, 50 mm × 4.6 mm, Phenomenex) using water and
methanol containing 0.1% of formic acid as eluents (methanol content
from 25% to 65% over 20 min, flow 1 mL/min, λ = 265 nm).
Retention time: 15.6 min.
5-Tosyloxy-1-pentanol. 1,5-Pentanediol (4.0 g, 40 mmol), p-
toluenesulfonyl chloride (7.3 g, 42 mmol), and pyridine (3.9 mL, 50
mmol) were dissolved in DCM (20 mL), and the resulting solution
was stirred overnight at room temperature. The reaction mixture was
diluted with DCM and washed three times with water. The organic
layer was dried with MgSO4, and the solvent was removed in vacuo.
The crude mixture was suspended in methanol to precipitate pentane
di(p-toluenesulfonate). The white solid was removed by filtration, and
the filtrate was concentrated in vacuo. The resulting crude product was
purified by liquid chromatography on silica gel using a gradient of
petroleum ether and ethyl acetate (from 0% to 60% of ethyl acetate).
5-Tosyloxy-1-pentanol: 53% yield (3.8 g). 1H NMR (CDCl3, 600
MHz): δ 7.78 (d, J = 8.40 Hz, 2 H, ArH), 7.34 (d, J = 7.80 Hz, 2 H,
ArH), 4.02 (t, J = 6.60 Hz, 2 H, CH2OH), 4.59 (t, J = 6.60 Hz, 2 H,
CH2OTs), 2.44 (s, 3 H, CH3), 1.68−1.53 (m, 2 H, CH2CH2OH),
1.52−1.49 (m, 2 H, CH2CH2OTs), 1.41−1.36 (m, 2 H,
CH2CH2CH2OH). 13C NMR (CDCl3): δ 144.9, 133.1, 129.8, 128.0,
70.6, 62.6, 60.6, 53.6, 31.9, 28.7, 21.6. Accurate mass (EI) m/z calcd
for C12H18O4S (M+) 258.09203, found 258.09246. Pentane di(p-
toluenesulfonate): 18% yield (2.8 g). 1H NMR (CDCl3, 600 MHz): δ
7.76 (d, J = 8.40 Hz, 4 H, ArH), 7.34 (d, J = 7.80 Hz, 4 H, ArH), 3.96
(t, J = 6.00 Hz, 4 H, CH2OTs), 2.45 (s, 6 H, CH3), 1.60 (m, 4 H,
TsOCH2CH2), 1.34 (m, 2 H, TsOCH2CH2CH2). 13C NMR (CDCl3):
δ 145.0, 133.0, 129.8, 128.2, 70.1, 28.3, 21.6, 21.5. Accurate mass (CI)
m/z calcd for C19H25O6S2 (M + H)+ 413.10925, found 413.10940.
(5-Fluoropentyl)tosylate. 5-Tosyloxy-1-pentanol (1 g, 3.87
mmol) and diethylaminosulfur trifluoride (DAST) (2.6 mL, 19.4
mmol) were dissolved in DCM (20 mL) at 0 °C, and the resulting
solution was allowed to gradually reach room temperature with stirring
over 4 h. The reaction mixture was diluted with DCM (100 mL) and
washed with brine (100 mL × 1) and twice with water (100 mL × 2).
The organic layer was dried with MgSO4, and the solvent was removed
in vacuo. The product was purified by liquid chromatography on silica
gel using petrol ether and ethyl acetate (90:10), to give the title
1
Compound 14. H NMR (CDCl3, 600 MHz): δ 8.83 (s, 1 H, H-2),
8.19 (s, 1 H, H-8), 7.46 (d, J = 7.8 Hz, 2 H, ArH), 7.07 (d, J = 8.4 Hz,
2 H, ArH), 4.69 (t, J = 4.8 Hz, 2 H, CH2CH2OTs), 4.45 (t, J = 4.8 Hz,
2 H, CH2OTs), 2.33 (s, 3 H, CH3). 13C NMR (CDCl3): δ 162.2,
152.5, 149.9, 145.6, 142.3, 131.1, 130.0, 127.5, 121.6, 67.3, 46.2, 29.8,
21.7. Accurate mass (EI) m/z calcd for C14H13N4O3SCl (M)+
352.03914, found 352.03958. IR (cm−1): υmax 3110, 3082, 3016,
2970, 1831, 1718. Mp: 166
1 °C. Compound 14a. 1H NMR
(CDCl3, 600 MHz): δ 8.56 (s, 1 H, H-2), 8.06 (s, 1 H, H-8), 7.45 (d, J
= 8.4 Hz, 2 H, ArH), 7.09 (d, J = 7.8 Hz, 2 H, ArH), 4.51 (t, J = 4.8
Hz, 2 H, CH2CH2OTs), 4.45 (t, J = 4.8 Hz, 2 H, CH2OTs), 2.37 (s, 3
H, CH3). 13C NMR (CDCl3): δ 152.2, 151.15, 151.12, 145.6, 145.59,
131.6, 131.4, 129.8, 127.6, 66.2, 43.7, 21.7. Accurate mass (EI) m/z
calcd for C14H13N4O3SBr (M)+ 352.03914, found 352.03974. IR
(cm−1): υmax 3112, 3083, 2960, 1765. Mp: 175 1 °C.
6-Bromo-7-(2-tosyloxyethyl)purine (15). A mixture of 6-bromo-
purine (2) (500 mg, 2.51 mmol), ethylene di(p-toluenesulfonate) (1.2
g, 3.27 mmol), and NaH (60% dispersed in oil, 111 mg, 2.76 mmol) in
anhydrous DMF (15 mL) was reacted according to the general
alkylation procedure to give 15 (40 mg, 4%) and the corresponding
1
N9-isomer 15a (399 mg, 40%) as white solids. Compound 15. H
NMR (CDCl3, 600 MHz): δ 8.78 (s, 1 H, H-2), 8.19 (s, 1 H, H-8),
7.46 (d, J = 8.22 Hz, 2 H, ArH), 7.07 (d, J = 8.10 Hz, 2 H, ArH), 4.72
(t, J = 4.86 Hz, 2 H, CH2CH2OTs), 4.48 (t, J = 5.04 Hz, 2 H,
CH2OTs), 2.33 (s, 3 H, CH3). 13C NMR (CDCl3): δ 161.3, 152.4,
150.1, 145.6, 1325.5, 131.1, 129.9, 127.5, 123.8, 67.3, 45.7, 21.7.
Accurate mass (CI) m/z calcd for C14H14N4O3SBr (M + H)+
396.99700, found 396.99825. IR (cm−1): υmax 2996, 2965, 2920,
1917, 1772. Mp: 165 1 °C. Compound 15a. 1H NMR (CDCl3, 600
MHz): δ 8.53 (s, 1 H, H-2), 8.07 (s, 1 H, H-8), 7.45 (d, J = 8.28 Hz, 2
H, ArH), 7.09 (d, J = 7.98 Hz, 2 H, ArH), 4.50 (t, J = 4.44 Hz, 2 H,
CH2CH2OTs), 4.45 (t, J = 4.98 Hz, 2 H, CH2OTs), 2.37 (s, 3 H,
CH3). 13C NMR (CDCl3): δ 151.8, 149.8, 145.6, 145.5, 143.3, 134.2,
131.3, 129.8, 127.5, 66.2, 43.7, 21.7. Accurate mass (CI) m/z calcd for
C14H14N4O3SBr (M + H)+ 396.99700, found 396.99792. IR (cm−1):
υmax 3113, 2989, 2959, 2914, 1921. Mp: 175 1 °C.
1
compound as colorless oil in 70% yield (700 mg). H NMR (CDCl3,
600 MHz): δ 7.78 (d, J = 8.28 Hz, 2 H, ArH), 7.34 (d, J = 8.11 Hz, 2
H, ArH), 4.39 (dt, JF,H = 47.23 Hz, J1,2 = 6.00 Hz, 2 H, CH2F), 4.03 (t,
J = 6.36 Hz, 2 H, TsOCH2), 2.44 (s, 3 H, CH3), 1.71−1.65 (m, 2 H,
TsOCH2CH2), 1.64−1.59 (m, 2 H, FCH2CH2), (m, 2 H,
FCH2CH2CH2). 13C NMR (CDCl3): δ 144.9, 133.1, 130.0, 127.8,
84.3, 83.2, 70.4, 29.9, 29.7, 28.6, 27.8, 21.5, 21.4. Accurate mass (EI)
m/z calcd for C12H17FO3S (M)+ 260.08769, found 260.08743.
6-Chloro-7-(5-tosyloxypentyl)purine (16). A mixture of 6-chlor-
opurine (1) (500 mg, 3.24 mmol), pentane di(p-toluenesulfonate)
(1.7 g, 4.21 mmol), and NaH (60% dispersed in oil, 142 mg, 3.56
mmol) in anhydrous DMF (15 mL) was reacted according to the
general alkylation procedure to give 16 (115 mg, 9%) and the
corresponding N9-isomer 16a (810 mg, 64%) as yellow oils.
S-[6-(7-(2-Fluoroethyl)purinyl)]glutathione (17). Compound
17 was prepared following a modified literature procedure.24 Briefly,
11 (10 mg, 0.05 mmol) and GSH (33.7 mg, 0.11 mmol) dissolved in
300 μL of a solution of NaOH (1 M) and ethanol (1:1) were stirred
for 4 h at 50 °C. The crude mixture was filtered over a plug of silica,
and the silica plug was washed with a solution of ethyl acetate/
methanol (1:1), and the product was eluted with methanol. The
fraction containing the product was concentrated under reduced
pressure, and the crude product was further purified by semi-
preperative HPLC using a Zorbax ODS column (C18, 5 μm, 9.4 mm
× 250 mm, Agilent). The flow rate was 2 mL/min with a mobile phase
of water and methanol containing 0.1% trifluoroacetic acid (TFA).
The methanol content was increased from 10% to 30% over 20 min
and then kept constant at 30% for 7 min. The UV absorbance detector
was set at 288 nm. Retention time of 17: 23.4 min. Compound 17 was
isolated in 84% yield (25 mg). 1H NMR (D2O, 500 MHz): δ 8.72 (s, 1
H, H-2), 8.49 (s, 1 H, H-8), 4.83 (s, 2 H, CH2aCH2cF), 4.78 (m, 2 H,
CH-Cys, CH2bCH2F), 4.75 (t, J = 1.86 Hz, 1 H, CH2CH2dF), 3.95 (dd,
J = 14.43 Hz, J = 5.12 Hz, 1 H, CH2a-Cys), 3.93 (s, 2 H, CH2−Gly),
3.81 (t, J = 6.56 Hz, 1 H, CH-Glu), 3.66 (dd, J = 14.46 Hz, J = 8.09
Hz, 1 H, CH2b-Cys), 2.39−2.33 (m, 2 H, CH2α-Glu), 2.01−1.98 (m, 2
H, CH2β-Glu). 13C NMR (D2O): δ 175.0, 173.5, 173.0, 172.6, 156.7,
154.9, 152.1, 150.1, 124.0, 83.6, 82.5, 53.7, 53.5, 48.9, 48.7, 41.8, 31.7,
31.2, 26.3. Accurate mass (ES−) m/z calcd for C17H21FN7O6S (M −
1
Compound 16. H NMR (CDCl3, 600 MHz): δ 8.86 (s, 1 H, H-2),
8.22 (s, 1 H, H-8), 7.74 (d, J = 7.80 Hz, 2 H, ArH), 7.33 (d, J = 7.80
Hz, 2 H, ArH), 4.44 (t, J = 7.20 Hz, 2 H, CH2(CH2)4OTs), 4.00 (t, J =
6.0 Hz, 2 H, CH2OTs), 2.43 (s, 3 H, CH3), 1.91 (m, 2 H,
CH2(CH2)3OTs), 1.71 (m, 2 H, CH2CH2OTs), 1.41 (m, 2 H,
CH2(CH2)2OTs). 13C NMR (CDCl3): δ 162.1, 152.6, 149.1, 145.1,
143.0, 132.9, 130.1, 127.9, 122.4, 69.8, 47.3, 44.5, 31.2, 29.6, 22.6, 21.8.
Accurate mass (ES+) m/z calcd for C17H20ClN4O3S (M + H)+
395.0945, found 395.0944. IR (cm−1): υmax 3059, 2937, 2865.
Analytical HPLC: Chromolith performance column, RP18-e (100
mm × 4.6 mm, Merck), using water and methanol containing 0.1% of
formic acid as eluents (methanol content from 15% to 70% over 9
min, flow 3 mL/min, λ = 265 nm). Retention time: 6.8 min.
1
Compound 16a. H NMR (CDCl3, 600 MHz): δ 8.73 (s, 1 H, H-2),
8.06 (s, 1 H, H-8), 7.40 (d, J = 7.80 Hz, 2 H, ArH), 7.32 (d, J = 8.40
Hz, 2 H, ArH), 4.27 (t, J = 7.20 Hz, 2 H, CH2(CH2)4OTs), 4.00 (m, 2
H, CH2OTs), 2.43 (s, 3 H, CH3), 1.91 (m, 2 H, CH2(CH2)3OTs),
1.70 (m, 2 H, CH2CH2OTs), 1.39 (m, 2 H, CH2(CH2)2OTs). 13C
NMR (CDCl3): δ 152.0, 151.9, 151.2, 145.2, 145.0, 132.9, 131.7,
130.0, 127.9, 69.9, 44.3, 29.4, 29.3, 22.8, 21.8. Accurate mass (ES+) m/
z calcd for C17H20ClN4O3S (M + H)+ 395.0945, found 395.0941. IR
(cm−1): υmax 3070, 2942, 2867, 1737. Analytical HPLC: Luna C18(2)
1029
dx.doi.org/10.1021/jm401764a | J. Med. Chem. 2014, 57, 1023−1032