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4.2.2.4. Synthesis of 4-(4-bromophenyl)-2-phenylpyrimido[1,2-
(75.46 MHz, DMSO-d6) d: 103.13, 115.46, 115.47, 120.59, 125.22,
126.01, 126.02, 126.88, 126.89, 127.98, 128.08, 128.09, 128.21,
130.03, 133.0, 138.11, 142.45, 149.85, 150.10, 155.12, 159.14; MS
(m/z): 365 (M+). (Found: C, 79.16; H, 4.29; N, 11.35. C24H16FN3 re-
quires C, 78.89; H, 4.41; N, 11.50.)
a]benzimidazole (7d). M.p. = >300 °C; IR (KBr): 1613 (C@N)cmÀ1
;
1H NMR (300 MHz, DMSO-d6) d: 7.32–7.92 (m, 13H, ArH’s), 7.99
(s, 1H, H-3); 13C NMR (75.46 MHz, DMSO-d6) d: 104.00, 113.54,
116.89, 124.22, 126.13, 126.85, 127.12, 128.45, 131.85, 133.87,
133.98, 138.58, 141.12, 146.00, 150.05, 156.10, 158.19; MS (m/z):
400 (M+). (Found: C, 66.13; H, 3.49; N, 10.42. C22H14BrN3 requires
C, 66.01; H, 3.53; N, 10.50)
4.3.2.3. 4-(4-chlorophenyl)-3,6-diphenyl-1H-pyrazolo[3,4-b]pyridine
(14c). M.p. = 283 °C; IR (KBr): 3148 (NH), 1590 (C@N)cmÀ1 1H
;
NMR (300 MHz, DMSO-d6) d: 7.22–7.81 (m, 14H, ArH’s), 7.91 (s,
1H, H-5), 14.10 (s, 1H, NH, D2O exchangeable); 13C NMR
(75.46 MHz, DMSO-d6) d: 103.01, 116.11, 125.20, 126.13, 126.14,
126.94, 127.18, 128.08, 128.09, 128.89, 132.84, 136.05, 140.0,
141.12, 148.14, 151.13, 155.12, 156.78; MS (m/z): 381 (M+).
(Found: C, 75.78; H, 4.08; N, 10.85. C24H16ClN3 requires C, 75.49;
H, 4.22; N, 11.00.)
4.2.2.5. Synthesis of 4-(2-chlorophenyl)-2-phenylpyrimido[1,2-a]benz
imidazole (7e). M.p. = 272 °C; IR (KBr): 1611 (C@N)cmÀ1 1H NMR
;
(300 MHz, DMSO-d6) d: 6.75–7.49 (m, 13H, ArH’s), 7.68 (s, 1H, H-
3); 13C NMR (75.46 MHz, DMSO-d6) d: 103.54, 112.14, 115.11,
122.12, 127.47, 127.87, 128.25, 129.82, 129.97, 131.15, 131.87,
133.45, 134.85, 136.14, 136.89, 140.11, 145.00, 151.09, 155.02,
158.00; MS (m/z): 355 (M+). (Found: C, 74,41; H, 3.92; N, 11.71.
C22H14ClN3 requires C, 74.26; H, 3.97; N, 11.81.)
4.3.2.4. 1,3,4,6-tetraphenyl-1H-pyrazolo[3,4-b]pyridine (14d). M.p. =
>300 °C; IR (KBr): 1610 (C@N)cmÀ1 1H NMR (300 MHz, DMSO-
;
4.2.2.6. Synthesis of 4-(4-methoxyphenyl)-2-phenylpyrimido[1,2-
d6) d: 7.05–7.72 (m, 20H, ArH’s), 7.92 (s, 1H, H-5); 13C NMR
(75.46 MHz, DMSO-d6) d: 109.00, 117.22, 120.25, 120.26, 125.25,
127.14, 127.15, 127.17, 127.18, 128.08, 128.09, 128.87, 128.88,
128.94, 128.99, 129.07, 129.08, 133.00, 138.58, 139.00, 141.55,
149.92, 150.70, 155.18; MS (m/z): 423 (M+). (Found: C, 85.26; H,
4.94; N, 9.80. C30H21N3 requires C, 85.08; H, 5.00; N, 9.92.)
a]benzimidazole (7f). M.p. = >300 °C; IR (KBr): 1613 (C@N)cmÀ1
;
1H NMR (300 MHz, DMSO-d6) d: 3.95 (s, 3H, OCH3), 7.32–7.89
(m, 13H, ArH’s), 7.78 (s, 1H, H-3); 13C NMR (75.46 MHz, DMSO-
d6) d: 52.12, 104.04, 112.55, 114.21, 116.58, 122.54, 127.37,
127.95, 128.45, 129.22, 131.59, 133.45, 133.89, 136.89, 145.21,
148.10, 151.55, 158.87; MS (m/z): 351 (M+). (Found: C, 78.86; H,
4.76; N, 11.83. C23H17N3O requires C, 78.61; H, 4.88; N, 11.96.)
4.3.2.5. 4-(4-fluorophenyl)-1,3,6-triphenyl-1H-pyrazolo[3,4-b]pyri-
dine (14e). M.p. = >300 °C; IR (KBr): 1613 (C@N)cmÀ1 1H NMR
;
4.3. Typical procedure for synthesis of pyrazolo[3,4-b]pyridines deriv-
atives 14a–f
(300 MHz, DMSO-d6) d: 7.14–7.79 (m, 19H, ArH’s), 7.81 (s, 1H, H-
5); 13C NMR (75.46 MHz, DMSO-d6) d: 108.47, 115.14, 115.15,
120.14, 121.49, 121.50, 125.12, 126.34, 127.47, 127.48, 127.97,
127.98, 128.10, 128.11, 128.12, 129.22, 129.43, 130.07, 133.00,
139.50, 139.87, 140.95, 146.09, 149.89, 150.12, 155.01, 161.00;
MS (m/z): 441 (M+). (Found: C, 81.92; H, 4.39; N, 9.29. C30H20FN3
requires C, 81.61; H, 4.57; N, 9.52.)
4.3.1. Silent reactions
A solution of 1-phenyl-2-(phenylsulfonyl)ethanone (1 mmol),
aldehyde (1 mmol), 5-aminopyrazole derivatives (1 mmol) and
p-TsOH (0.2 mmol) in 15 ml of absolute ethanol was refluxed for
appropriate time (cf. Table 2) until completion of the reaction. After
completion of the reaction as indicated by TLC (EtOAc/n-hexene,
1:2), the reaction mixture was allowed to cool. The solvent was re-
moved by evaporation and the residue was washed with H2O
(2 Â 20 ml). The solid products were purified by recrystallization
from 2-propanol.
4.3.2.6. 4-(4-chlorophenyl)-1,3,6-triphenyl-1H-pyrazolo[3,4-b]pyri-
dine (14f). M.p. = >300 °C; IR (KBr): 1610 (C@N)cmÀ1 1H NMR
;
(300 MHz, DMSO-d6) d: 7.09–7.80 (m, 19H, ArH’s), 7.89 (s, 1H, H-
5); 13C NMR (75.46 MHz, DMSO-d6) d: 109.02, 115.09, 116.58,
116.59, 120.25, 121.05, 123.98, 123.99, 124.12, 124.13, 127.55,
127.57, 128.45, 128.46, 128.70, 133.00, 134.78, 139.45, 140.12,
140.95, 144.81, 149.00, 151.78, 155.04; MS (m/z): 457 (M+).
(Found: C, 78.48; H, 4.35; N, 9.03. C30H20ClN3 requires C, 78.68;
H, 4.40; N, 9.18.)
4.3.2. Sonicated reactions
These processes were performed on the same scale described
above for silent reactions. All The reactions were kept at room tem-
perature 25–30 °C (the temperature inside reaction vessel was 28–
30 °C). The sonochemical reactions were continued for suitable
time (cf. Table 2) until the starting materials were no longer detect-
able by TLC. The products were obtained and purified as described
above in silent reaction procedures.
5. X-ray crystallography
A single crystal of compound 7b was obtained by slow evapora-
tion from a mixture of ethanol:DMF (2:1). The crystal structure
was solved and refined using maxus (nonius, Deflt and MacScience,
The synthesized compounds with their physical data are listed
below.
Japan) [58] Mo Ka radiation (k = 0.71073 Å) and a graphite mono-
chromator were used for data collection. The chemical formula and
ring labeling system is shown in Fig. 1.
Crystallographic data (excluding structure factors) for the struc-
ture in this paper have been deposited with the Cambridge Crystal-
lographic Data Centre as supplementary publication number CCDC
793678 Copies of the data can be obtained, free of charge, on appli-
cation to CCDC, 12 Union, Road, Cambridge CB2 1EZ, UK [fax: 144
(0)1223 336033 or e-mail: deposit@ccdc.cam.ac.uk].
4.3.2.1. 3,4,6-triphenyl-1H-pyrazolo[3,4-b]pyridine (14a). M.p. =
278 °C; IR (KBr): 3119 (NH), 1595 (C@N)cmÀ1
;
1H NMR
(300 MHz, DMSO-d6) d: 7.10–7.81 (m, 15H, ArH’s), 7.84 (s, 1H, H-
5), 14.01 (s, 1H, NH, D2O exchangeable); 13C NMR (75.46 MHz,
DMSO-d6) d: 103.95, 117.25, 125.21, 125.88, 125.89, 125.97,
126.01, 127.70, 128.69, 128.97,128.99, 129.02, 130.15, 137.18,
140.87, 144.45, 149.85, 151.14, 154.07; MS (m/z): 347 (M+).
(Found: C, 83.19; H, 4.84; N, 11.97. C24H17N3 requires C, 82.97;
H, 4.93; N, 12.10.)
4.3.2.2. 4-(4-fluorophenyl)-3,6-diphenyl-1H-pyrazolo[3,4-b]pyridine
Appendix A. Supplementary data
(14b). M.p. = 289 °C; IR (KBr): 3174 (NH), 1592 (C@N)cmÀ1 1H
;
NMR (300 MHz, DMSO-d6) d: 7.19–7.79 (m, 14H, ArH’s), 7.74 (s,
Supplementary data associated with this article can be found, in
1H, H-5), 14.12 (s, 1H, NH, D2O exchangeable); 13C NMR