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M. Maryska et al.
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CHPu) ppm; 13C NMR (75 MHz, CDCl3): d = 18.0, 53.3,
54.9, 122.2, 142.7, 147.2, 152.3, 161.6, 169.9 ppm; HRMS
(ESI): m/z calcd for C9H9ClN4NaO2 263.03062, found
263.03074.
8.21 (s, 1H, CHPu), 12.30 (br s, 1H, NH) ppm; 13C NMR
(75 MHz, DMSO-d6): d = 48.2, 114.8, 117.4, 134.2,
143.7, 144.6, 154.3, 157.1 ppm; HRMS (ESI): m/z calcd
for C8H8N4NaO 199.05903, found 199.05903.
6-Chloro-7-phenacylpurine (2e, C13H9ClN4O)
7-Propargylhypoxanthine (4c, C8H6N4O)
1
Yellow solid; 0.661 g (54 % overall yield from 1a); m.p.:
187 °C (decomp.); 1H NMR (300 MHz, DMSO-d6):
d = 6.25 (s, 2H, CH2), 7.65 (m, 2H, CHPh), 7.75 (m, 1H,
CHPh), 8.10 (m, 2H, CHPh), 8.74 (s, 1H, CHPu), 8.84 (s, 1H,
CHPu) ppm; 13C NMR (75 MHz, DMSO-d6): d = 53.3,
122.8, 128.2, 129.2, 133.6, 134.6, 151.6, 151.8, 161.5,
193.1 ppm; HRMS (ESI): m/z calcd for C13H9ClN4NaO
295.03571, found 295.03586.
White solid; 0.127 g (93 %); m.p.: 236 °C (decomp.); H
NMR (300 MHz, DMSO-d6): d = 3.54 (t, 1H, J = 2.3 Hz,
CH), 5.24 (d, 2H, J = 2.3 Hz, CH2), 7.99 (s, 1H, CHPu),
8.30 (s, 1H, CHPu), 12.39 (br s, 1H, NH) ppm; 13C NMR
(75 MHz, DMSO-d6): d = 35.8, 76.7, 78.2, 114.6, 143.4,
144.9, 154.2, 157.0 ppm; HRMS (ESI): m/z calcd for
C8H6N4NaO 197.04338, found 197.04337.
Methyl 2-(1,6-dihydro-6-oxopurine-7-yl)propionate
(4d, C9H10N4O3)
7-Allyl-6-chloropurine-2-amine (3b, C8H8ClN5)
1
Yellow solid; 0.170 g (58 % overall yield from 1b); m.p.:
180 °C (decomp.); 1H NMR (300 MHz, DMSO-d6):
d = 4.90 (m, 3H, CH and CH2), 5.17 (d, J = 10.5 Hz,
1H, CH), 6.05 (m, 1H, CH), 6.63 (br s, 2H, NH2), 8.36 (s,
1H, CHPu) ppm; 13C NMR (75 MHz, DMSO-d6):
d = 48.2, 115.1, 117.1, 134.4, 142.5, 149.7, 160.2,
164.3 ppm; HRMS (ESI): m/z calcd for C8H8ClN5Na
232.03604, found 232.03688.
White solid; 0.418 g (90 %); m.p.: 189–191 °C; H NMR
(300 MHz, DMSO-d6): d = 1.78 (d, 3H, J = 7.3 Hz,
CH3), 3.66 (s, 3H, CH3), 5.65 (q, 1H, J = 7.3 Hz, CH),
8.00 (s, 1H, CHPu), 8.34 (s, 1H, CHPu), 12.35 (br s, 1H,
NH) ppm; 13C NMR (75 MHz, DMSO-d6): d = 17.7, 52.7,
54.7, 114.9, 143.1, 144. 8, 154.2, 157.3, 170.4 ppm; HRMS
(ESI): m/z calcd for C9H10N4NaO3 245.06451, found
245.06456.
Methyl 2-(2-amino-6-chloropurine-7-yl)propanoate
(3d, C9H10ClN5O2)
7-Phenacylhypoxanthine (4e, C13H10N4O2)
1
White solid; 0.119 g (94 %); m.p.: 261 °C (decomp.); H
1
Yellow solid; 0.172 g (72 % overall yield from 1b); H
NMR (300 MHz, DMSO-d6): d = 6.03 (s, 2H, CH2), 7.62
(m, 2H, ArH), 7.76 (m, 1H, ArH), 7.99 (s, 1H, CHPu), 8.07
(m, 2H, CHAr), 8.17 (s, 1H, CHPu), 12.31 (br s, 1H, NH)
ppm; 13C NMR (75 MHz, DMSO-d6): d = 52.9, 115.6,
128.1, 129.1, 134.0, 134.2, 144.6, 144.7, 154.4, 156.9,
192.7 ppm; HRMS (ESI): m/z calcd for C13H10N4NaO2
277.06960, found 277.06965.
NMR (300 MHz, DMSO-d6): d = 1.81 (d, J = 7.2 Hz,
3H, CH3), 3.69 (s, 3H, CH3), 5.61 (q, J = 7.2 Hz, 1H, CH),
6.68 (s, 2H, NH2), 8.50 (s, 1H, CHPu) ppm; 13C NMR
(75 MHz, DMSO-d6): d = 17.1, 53.0, 55.7, 107.4, 140.3,
151.3, 153.1, 153.8, 169.6 ppm.
General procedure for conversion of N7-substituted
6-chloropurines to N7-substituted hypoxanthines
7-Allylguanine (5b, C8H9N5O)
Beige solid; 0.185 g (96 %); m.p.: [270 °C; 1H NMR
(300 MHz, DMSO-d6): d = 4.80 (d, J = 5.4 Hz, 2H,
CH2), 5.00 (d, J = 17.1 Hz, 1H, CH), 5.14 (d,
J = 10.8 Hz, 1H, CH), 6.26 (s, 2H, NH2), 7.86 (s, 1H,
CHPu), 10.89 (s, 1H, NH) ppm; 13C NMR (125 MHz,
DMSO-d6): d = 47.9, 107.9, 117.1, 134.4, 142.7, 153.1,
154.4, 159.7 ppm; HRMS (ESI): m/z calcd for C8H9N5NaO
214.06993, found 214.07056.
A solution of starting 6-chloropurine 2 or 3 (1 mmol) in
10 cm3 of formic acid was heated for 2 h at 75 °C. The
mixture was evaporated in vacuo, 10 cm3 of ethanol was
added, and the resultant mixture was refluxed for 30 min.
Evaporation under reduced pressure and column chroma-
tography (silica gel, dichloromethane/methanol, 10:1) gave
the final product.
Methyl 2-(2-amino-1,6-dihydro-6-oxopurine-7-yl)propanoate
(5d, C9H11N5O3)
7-Methylhypoxanthine (4a)
White solid; 0.428 g (95 %); m.p.: [270 °C (Ref. [40]
355–357 °C); H NMR in accordance with the literature
data [46].
1
White solid; 0.027 g (97 %); m.p.: 261 °C (decomp.); H
1
NMR (300 MHz, DMSO-d6): d = 1.71 (d, J = 7.3 Hz,
3H, CH3), 3.63 (s, 3H, CH3), 5.49 (q, J = 7.3 Hz, 1H, CH),
6.51 (br s, 2H, NH2), 8.01 (s, 1H, CHPu) ppm; 13C NMR
(125 MHz, DMSO-d6): d = 17.6, 52.5, 54.3, 107.9, 142.1,
153.3, 154.5, 159.9, 170.6 ppm; HRMS (ESI): m/z calcd
for C9H11N5NaO3 260.07541, found 260.07633.
7-Allylhypoxanthine (4b, C8H8N4O)
1
White solid; 0.153 g (87 %); m.p.: 236–237 °C; H NMR
(300 MHz, DMSO-d6): d = 4.94–5.07 (m, 3H, CH2, CH2),
5.18 (m, 1H, CH2), 6.09 (m, 1H, CH), 7.96 (s, 1H, CHPu),
123