Synthesis of some nitrogen heterocycles and in vitro evaluation of their antimicrobial and antitumor activity

Article abstract of DOI:10.1007/s11164-012-0981-3

Treatment of ethyl β-aryl-α-cyanoacrylate (2a, b) with thiourea, guanidine hydrochloride, and thiosemicarbazide in presence of anhydrous potassium carbonate in methanol led to formation of pyrimidine derivatives 3 and 5 and thiosemicarbazone derivative 9.

Full text of DOI:10.1007/s11164-012-0981-3

Res Chem Intermed
DOI 10.1007/s11164-012-0981-3
Synthesis of some nitrogen heterocycles and in vitro
evaluation of their antimicrobial and antitumor activity
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•
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J. A. Hasanen I. M. El-Deen R. M. El-Desoky
A. M. Abdalla
Received: 13 November 2012 / Accepted: 15 December 2012
Ó Springer Science+Business Media Dordrecht 2013
Abstract Treatment of ethyl b-aryl-a-cyanoacrylate (2a, b) with thiourea, gua-
nidine hydrochloride, and thiosemicarbazide in presence of anhydrous potassium
carbonate in methanol led to formation of pyrimidine derivatives 3 and 5 and
thiosemicarbazone derivative 9. Thiazole derivative 10 was prepared via cyclization
of thiosemicarbazone derivative 9 with 4-methoxy phenacyl bromide. Acetylation
of 3a, 5, and 10 with acetic anhydride yielded the acetoxy and N-acetyl derivatives
4, 6, and 11. The mass-spectral fragmentation patterns of nitrogen heterocycles were
investigated to elucidate the structure of the prepared compounds. Biological studies
of nitrogen heterocycles were carried out to investigate their antimicrobial and
anticancer activities; it was found that compounds 5, 10, and 11 were highly active
against bacteria and fungi, and compounds 3a and 3b were also active against
bacteria and fungi.
Keywords Synthesis Á Biological activity Á Pyrimidine Á Thiazole
Introduction
Nitrogen heterocycles in general, and pyrimidines in particular, are found in several
biologically active natural products and exhibit considerable therapeutic potential
[1]. The wide-spectrum biological activities such as antiallergic [2], antitumor [3],
antipyretic [4], anti-inflammatory [4], and antiparasitic [5] activities exhibited by
synthetic pyrimidine-based scaffolds and a number of analogs have attracted
considerable attention. During a screening effort for antiviral agents, we found that
J. A. Hasanen Á R. M. El-Desoky Á A. M. Abdalla
Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt
I. M. El-Deen (&)
Chemistry Department, Faculty of Science, Port-said University, Port-said, Egypt
e-mail: eldeen.i811@yahoo.com
123

J. A. Hasanen et al.
multifunctional tetrahydropyrimidine derivatives bearing bulky C-2 alkyl substituents
exhibit cytostatic activity and inhibit proliferation of murine leukemia and murine
mammary carcinoma cells [6]. 3,4-Dihydropyrimidine-2-(1H)-ones (DHLMS) and
their appropriately functionalized derivatives have interesting pharmacological
profiles [7, 8].
In view of this, 6-aryl-5-cyano-4-hydroxy-2-mercaptopyrimidines (3), 6-(3-nitro-
phenyl)-5-cyano-4-hydroxy-2-aminopyridine (5), and 5-bromo-2-hydroxybenzalde-
hyde thiosemicarbazone (9) were prepared by condensation of ethyl b-aryl-
a-cyanoacrylate (2) with thiourea, guanidine hydrochloride, and thiosemicarbazide
in presence of anhydrous potassium carbonate in methanol. These pyrimidine and
thiazole derivatives were investigated for antimicrobial and antitumor activity.
Materials and methods
Melting points were determined in capillaries with a MEL-TEMP II apparatus and
are reported uncorrected. Infrared spectra were taken on a PerkinElmer 337
spectrophotometer using KBr wafers. Proton nuclear magnetic resonance (NMR)
spectra were obtained on a Varian EM 360 spectrometer using a solution in
hexadeuteriodimethyl sulfoxide with tetramethylsilane as internal standard. Mass
spectra were recorded on a VG Autspec GEI FAB and a Hewlett Packard MS-
Engine thermospray with ionization by electron impact at 70 eV. The accelerating
voltage was 6 kV. The temperature of the source was *200 °C, and the emission
current was *100 mA. Microanalyses were conducted using a PerkinElmer 2408
CHN analyzer.
Ethyl b-aryl-a-cyanoacrylate (2a, b)
A mixture of ethyl cyanoacetate (0.01 mol) and aromatic aldehydes (such as
5-bromo-2-hydroxybenzaldehyde and 3-nitrobenzaldehyde) (0.01 mol) in methanol
in the presence of anhydrous potassium carbonate (0.03 mol) was heated under
reflux for 1.5 h. The reaction mixture was cooled and acidified with diluted
hydrochloric acid. The solid formed was filtered off, washed with water, dried, and
purified by recrystallization from ethanol to give 2.
Ethyl b-(5-bromo-2-hydroxyphenyl)-a-cyanoacrylate as pale yellow crystals,
m.p. 122 °C. IR (KBr): 3,350–2,850 (br.OH), 2,250 (CN), 1,756 (C=O), 1,625
(C=C), 1,215, 1,095 (C–O) cm-1. 1H-NMR (DMSO-d6): d 1.3 (t, 3H, CH3), 4.35 (q,
2H, OCH2), 7.53–8.01 (m, 4H, Ar–H and H-olefinic), 11.33 (s, 1H, OH) ppm. MS
(m/z, %) = 297 (M??2, 53.3), 295 (M?, 56.30), 251 (56.40), 226 (87.50), 224
(100), 89 (81.30), 88 (62.50), 62.20 (93.80), 57 (68.80), 54 (75.00). Anal. Found: C,
48.61; H; 3.35; N, 4.71. C12H10NBrO3 requires: C, 8.81; H, 3.39; N, 4.74.
Ethyl b-(3-nitrophenyl)-a-cyanoacrylate (2b) as pale yellow, yield 76 %, m.p.
124 °C. IR (KBr): 2,223 (CN), 1,751 (C=O), 1,621 (C=C), 1,210, 1,095 (C–O)
cm-1. 1H-NMR (CDCl3): d 1.4 (t, 3H, CH3), 4.45 (q, 2H, OCH2), 7.12–7.89 (m, 5H,
Ar–H and H-olefinic) ppm. MS: m/z (%) = 247 (M??1, 3.20), 246 (M?, 13.1), 218
(41.20), 150 (41.20), 148 (58.80), 136 (64.70), 121 (41.20), 117 (41.20), 105
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Synthesis of some nitrogen heterocycles and their in vitro evaluation
(41.20), 101 (52.90), 91 (41.20), 85 (41.20), 83 (41.20), 76 (52.90), 69 (41.20), 67
(58.80), 66 (47.10), 65 (70.60), 60 (100), 58 (76.50), 57 (52.90), 55 (76.50), 50
(5.90). Anal. Found: C, 58.51; H, 4.06; N, 11.35. C12H10N2O4 requires: C, 58.54; H,
4.06; N, 11.38.
6-Aryl-5-cyano-4-hydroxy-2-substituted pyrimidines (3a and 5)
5-Bromo-2-hydroxybenzaldehyde thiosemicarbazone (9)
A mixture of 2a, b and thiourea, guanidine hydrochloride, and thiosemicarbazide
(0.01) in presence of anhydrous potassium carbonate (0.03 mol) in methanol
(50 ml) was heated under reflux for 2–3 h, then cooled and poured into dilute
hydrochloric acid (1 %). The solid formed was filtered off, washed with water,
dried, and purified by recrystallization from suitable solvent to give 3a, 5, and 9.
6-(5-Bromo-2-hydroxyphenyl)-5-cyano-4-hydroxy-2-mercaptopyrimidine (3a) as
pale yellow crystals, yield 68 %, m.p. 286 °C. IR (KBr): 3,390–2,850 (br-OH),
2,250 (CN), 1,635 (C=N), 1,618, 1,585 (C=C), 1,385 (C=S), 1,210, 1,083 (C–O)
1
cm-1. H-NMR (DMSO-d6): d 7.31–8.01 (m, 3H, Ar–H), 10.4 (s, 1H, NH), 11.30
(s, 1H, OH), 11.51 (s, 1H, OH) ppm. MS: m/z (%) = 325 (M??2, 83.60), 324
(M??1, 100), 323 (M?, 84.40), 310 (15.60), 309 (13.30), 308 (10.40), 307 (16.50),
297 (31.10), 296 (13.30), 293 (11.10), 292 (17.60), 291 (14.40), 290 (13.30), 269
(0.7), 268 (48.90), 267 (34.10), 266 (51.1), 265 (65.8), 264 (13.3), 239 (9.80), 238
(7.40), 237 (13.30), 94 (13.30), 93 (10.40), 90 (11.90), 89 (27.30), 86 (33.30), 85
(23.80), 82 (25.90), 81 (18.50), 80 (21.10), 79 (14.80), 71 (18.50), 69 (23.00), 68
(25.20), 64 (23.00), 63 (20.70), 61 (15.80), 60 (23.00), 59 (26.30), 58 (10.40), 56
(17.00), 53 (12.60), 52 (20.70), 50 (17.00). Anal. Found: C, 40.84; H, 1.83; N,
12.89; S, 9.89. C11H6N3BrO2S requires: C, 40.87; H, 1,86; N, 13.00; S, 9.91.
6-(3-nitrophenyl)-5-cyano-4-hydroxy-2-mercaptopyrimidine (3b) as yellow crys-
tals, yield 72 %, m.p. 278 °C. IR (KBr): 3,233 (NH), 3,390–2,850 (br.OH), 2,251
(CN), 1,631 (C=N), 1,617, 1,585 (C=C), 1,123 (C–O) cm-1. 1H-NMR (DMSO-d6):
d 7.31–8.15 (m, 4H, Ar–H), 10.21 (br-s, 1H, NH), 11.21 (s, 1H, OH) ppm. MS:
m/z (%) = 275 (M?1?1, 20.00), 274 (M?,23.00), 217 (12.50), 216 (30.00), 176
(50.00), 175 (95.00), 174 (52.50), 167 (17.50), 166 (47.50), 154 (17.50), 153
(12.30), 152 (15.00), 151 (22.50), 146 (30.00), 145 (32.50), 144 (25.00), 136 (100),
135 (42.50), 131 (22.50), 130 (20.00), 129 (60.00), 128 (77.50), 127 (37.50), 120
(20.00), 119 (90.00), 118 (52.50), 116 (57.50), 113 (37.50), 112 (15.00), 105
(30.00), 104 (22.50), 103 (70.00), 102 (55.00), 101 (47.50), 98 (40.00), 97 (22.50),
92 (12.50), 91 (67.50), 90 (62.50), 89 (52.50), 87 (25.00), 84 (32.50), 82 (22.50), 77
(82.50), 75 (42.50), 74 (32.50), 73 (35.00), 71 (40.00), 70 (40.00), 69 (65.00), 65
(40.00), 64 (52.50), 63 (80.00), 62 (27.50), 51 (47.50), 50 (65.00). Anal. Found: C,
48.03; H, 2.17; N, 20.35; S, 11.63. C11H6N4O3S requires: C, 48.17; H, 2.19; N,
20.44; S, 11.68.
6-(3-nitrophenyl)-5-cyano-4-hydroxy-2-aminopyrimidine (5) as pale yellow,
yield 63 %, m.p. 260 °C. IR (KBr): 3,385–2,875 (br.OH), 3,289, 3,171 (NH2),
2,255 (CN), 1,635 (C=N), 1,613, 1,589 (C=C), 1,172 (C–O) cm-1 1H-NMR
.
(DMSO-d6): d 6.21 (s, 2H, NH2), 7.31–8.10 (m, 4H, Ar–H), 11.23 (br-S, IH, OH)
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J. A. Hasanen et al.
ppm. MS: m/z (%) = 258 (M??1, 27.30), 257 (M?, 100), 256 (M?-1, 48.50), 255
(27.30), 239 (12.10), 238 (18.20), 216 (21.20), 215 (48.50), 214 (36.40), 210
(30.30), 205 (18.20), 185 (21.20), 169 (45.50), 168 (33.30), 167 (18.20), 165
(15.20), 159 (21.20), 157 (33.30), 156 (21.20), 151 (24.20), 150 (27.30), 149
(21.20), 143 (18.20), 142 (30.30), 141 (45.50), 131 (15.20), 129 (24.20), 128
(30.30), 127 (39.40), 118 (24.20), 116 (21.20), 115 (30.30), 114 (84.80), 113
(24.20), 106 (27.30), 105 (24.20), 103 (33.30), 102 (45.50), 101 (39.40), 99 (30.30),
98 (33.30), 97 (21.20), 91 (30.30), 89 (36.30), 87 (30.30), 84 (30.30), 82 (21.20), 81
(21.20), 80 (33.30), 77 (33.30), 76 (54.50), 75 (51.50), 73 (36.40), 71 (30.30), 70
(33.30), 69 (48.50), 68 (42.40), 67 (33.30), 66 (36.40), 65 (39.40), 64 (45.50), 63
(51.50), 62 (30,30), 57 (63.60), 56 (36.40), 55 (45.50), 54 (27.30), 51 (57.60), 50
(63.60). Anal. Found: C; 51.32; H; 2.69; N, 27.13. C11H7N5O3 requires: C, 51.36;
H, 2.72; N, 27.24.
5-Bromo-2-hydroxybenzaldehyde thiosemicarbazone (9) as pale yellow crystals,
yield 78 %, m.p. 225 °C. IR (KBr): 3,410–2,980 (br-OH), 3,320, 3,170 (NH2),
3,221 (NH), 1,631 (C=N), 1,382 (C=S), 1,185 (C–O) cm-1. 1H-NMR (DMSO-d6): d
4.83 (s, 2H, NH2), 7.12–7.91 (m, 3H, Ar–H), 8.31 (s, 1H, CH=N), 9.31 (s, IH, NH)
ppm. MS: m/z (%) = 275 (M??2, 47.60), 274 (M??1, 26.70), 273 (M?, 56.20),
258 (10.60), 257 (6.30), 256 (10.80), 200 (35.00), 199 (35.30), 198 (26.20), 197
(21.70), 187 (10.80), 186 (4.80), 171 (19.10), 170 (12.30), 164 (14.40), 157 (5.30),
155 (4.50), 143 (10.60), 135 (5.30), 134 (10.80), 119 (13.40), 118 (8.30), (27.0), 89
(12.10), 88 (7.10), 79 (13.40), 78 (21.40), 77 (69.50), 76 (64.00), 75 (29.50), 74
(25.90), 65 (21.00), 64 (25.90), 63 (73.30), 62 (35.30), 61 (25.70), 60 (100), 59
(31.00), 58 (13.10), 53 (39.00), 52 (17.90), 51 (47.40), 50 (34.50). Anal. Found: C,
35.01; H, 2.79; N, 15.23; S, 11.55; C8H8N3BrOS requires: C, 35.16; H, 2.93; N,
15.38; S, 11.72.
Acetylation of 3a and 5: formation of acetyl derivatives 4 and 6
A solution of 3a and/or 5 (0.01 mol) in acetic anhydride (15 ml) was heated under
reflux for 2 h, then cooled and poured into ice-water. The solid formed was filtered
off, washed with water, dried, and purified by recrystallization from benzene to give
4 and 6.
6-(5-Bromo-2-acetoxyphenyl)-5-cyano-4-hydroxy-2-mercaptopyrimidine (4) as
yellow crystals, yield 56 %, m.p. 160 °C. IR (KBr): 3,390–2,950 (br.OH), 2,253
(CN), 1,765 (CO), 1,633 (C=N), 1,615, 1,598 (C=C), 1,225, 1,097 (C–O) cm-1. 1H-
NMR (DMSO-d6): 2.41 (s, 3H, COCH3), 7.21–7.98 (m, 3H, Ar–H), 9.21 (s, 1H,
SH), 11.02 (s, 1H, OH) ppm. MS: m/z (%) = 367 (M??2, 6.50), 366 (M??1,
41.40), 365 (M?, 28.50), 364 (43.00), 363 (25.30), 349 (26.30), 348 (46.80), 347
(45.70), 346 (47.30), 345 (28.00), 344 (15.60) 98 (10.20), 97 (7.50), 90 (11.50), 89
(12.40), 88 (4.00), 87 (29.00), 86 (15.10), 85 (10.20), 80 (10.20), 79 (12.40), 77
(17.70), 76 (16.70), 75 (18.80),74 (10.80), 73 (8.60), 69 (25.30), 68 (12.40),65
(11.30), 64 (14.00), 63 (23.10), 62 (22.70), 61 (59.70), 60 (26.90), 53 (10.80), 51
(12.90), 50 (18.80). Anal. Found: C, 42.57; H, 2.05; N, 11.33; S, 8.61.
C13H8N3BrO3S requires C, 42.74; H, 2.19; N, 11.51; S, 8.77.
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Synthesis of some nitrogen heterocycles and their in vitro evaluation
6-(3-Nitrophenyl)-5-cyano-4-hydroxy-2-(acetyl)aminopyrimidine (6) as pale yel-
low crystals, yield 63 %, m.p. 124 °C. IR (KBr): 3,385–2,960 (br.OH), 3,221 (NH),
2,256 (CN), 1,695 (CO), 1,629 (C=N), 1,607, 1,593 (C=C), 1,121 (C–O), cm-1. 1H-
NMR (DMSO-d6): d 2.31 (s, 3H, COCH3), 7.41–8.01 (m, 4H, Ar–H), 10.10 (s, 1H,
NH), 11.21 (s, 1H, OH) ppm. MS: m/z (%) = 300 (M??1, 10.20), 299 (M*, 28.60),
292 (21.40), 259 (10.70), 258 (28.60), 257 (100), 229 (17.90), 218 (39.30), 217
(28.60), 216 (14.30), 215 (25.00), 212 (17.90), 211 (21.40), 210 (25.00), 201
(53.60), 200 (35.70), 195 (25.00), 186 (17.90), 185 (17.90), 183 (17.90), 182
(17.90), 176 (17.80), 175 (21.40), 174 (53.60), 173 (42.90), 172 (28.60), 155
(32.10), 152 (25.00), 150 (25.00), 143 (28.60), 142 (17.90), 141 (21.40), 140
(14.30), 137 (17.90), 136 (14.30), 129 (39.30), 128 (57.10), 127 (46.40), 126
(25.00), 117 (28.60), 116 (50.20), 103 (32.10), 102 (25.00), 101 (46.40), 100
(42.90), 99 (21.40), 91(14.30), 90 (25.00), 89 (39.30), 88 (35.70), 84 (32.10), 77
(32.10), 76 (50.10), 75 (57.10), 74 (42.90), 73 (39.30), 72 (25.00), 66 (25.00), 65
(25.00), 64 (35.70), 63 (64.30), 61 (39.30), 60 (71.40), 57 (39.30), 56 (28.60), 52
(32.10), 51 (60.70), 50 (67.90). Anal. Found: C, 52.01; H, 2.97; N, 23.22.
C13H9N5O4 requires: C, 52.17; H, 3.01; N, 23.41.
7-(3-Nitrophenyl)-6-cyano-5-hydroxy-imidazolo[2,1-b]pyrimidin-1-one (7)
A mixture of 5 (0.01 mol), ethyl chloroacetate (0.01 mol), and fused sodium acetate
(0.03 mol) in glacial acetic acid (30 ml) was heated under reflux for 4 h, then
cooled and poured into water. The resulting solid was filtered off, washed with
water, dried, and purified by recrystallization from dimethylformamide to give 7 as
pale yellow crystals, yield 62 %, m.p 293 °C. IR (KBr): 3,781–2,453 (br.OH), 3,026
(NH), 2,453 (CN), 1,718 (CO), 1,606 (C=N), 1,527 (C=C), 1,091 (C–O), cm-1
.
1H-NMR (DMSO-d6): d 3.25 (s, 2H, COCH2N), 7.21–8.01 (m, 4H, Ar–H), 11.31
(s, 1H, OH) ppm. MS: m/z (%) = 297 (M?, 5.80), 271 (7.10), 258 (14.90), 257
(100), 256 (49.40), 99 (20.10), 90 (11.00), 89 (13.60), 88 (16.90), 87 (13.00), 86
(10.40), 77 (18.20), 76 (31.80), 75 (33.80), 74 (20.80), 69 (20.80), 68 (14.90), 65
(14.40), 64 (18.80), 63 (18.80), 62 (16.20), 57 (20.10), 56 (13.60), 55 (10.40), 51
(40.30), 50 (48.70). Anal. Found: C, 52.33; H, 2.25; N, 23.47. C13H7N5O4 requires:
C, 52.23; H, 2.53; N, 23.57.
5-(4-Methoxyphenyl)-2-[(5-bromo-2-hydroxybenzylidene)-hydrazino]-thiazole
(10)
A mixture of 9 (0.01 mol), 4-methoxy phenacyl bromide (0.01 mol), and fused
sodium acetate (0.03 mol) in methanol (50 ml) was heated under reflux for 6 h, then
cooled and poured into water. The solid formed was filtered off, washed with water,
dried, and purified by recrystallization from ethanol to give 10 as orange crystals,
yield 67 %, m.p. 245 °C. IR (KBr): 3,950–2,890 (br.OH), 3,227 (NH), 1,635 (C=N),
1,605–1,585 (C=C), 1,211, 1,095 (C–O) cm-1. 1H-NMR (DMSO-d6): d 3.95 (s, 3H,
OCH3), 6.89–7.95 (m, 9H, Ar–H and H-thiazole), 8.31 (s, IH, CH=N), 10.33 (s, IH,
NH), 11.31 (s, 1H, OH) ppm. MS: m/z (%) = 405 (M??2, 12.30), 404 (M??1,
6.20), 403 (M?, 15.30), 388 (15.20), 387 (17.40), 386 (14.50), 385 (5.80), 370
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J. A. Hasanen et al.
(5.80), 369 (9.40), 368 (5.80), 358 (5.80), 355 (5.80), 338 (4.30), 336 (4.30), 288
(10.90), 287 (10.10), 286 (42.00), 285 (16.70), 284 (40.60), 283 (32.60), 279
(18.10), 278 (5.80), 277 (17.40), 276 (10.10), 271 (27.50), 270 (18.80), 269 (27.80),
242 (9.40), 241 (9.40), 239 (10.10), 237 (5.10), 229 (14.50), 228 (6.50), 227 (13.80),
212 (10.10), 211 (10.10), 210 (10.10), 207 (13.80), 206 (59.40), 205 (32.60), 204
(53.60), 203 91 (37.70), 90 (37.00), 89 (37.00), 82 (28.30), 81 (31.90), 80 (33.30),
79 (21.70), 77 (35.50), 76 (30.40), 75 (34.10), 69 (22.50), 68 (12.30), 66 (17.40), 65
(47.10), 64 (38.40), 63 (100), 62 (71.70), 61 (31.90), 53 (31.90), 51 (44.90), 50
(46.40). Anal. Found: C, 50.46; H, 3.27; N, 10.21; S, 7.79.
5-(4-Methoxyphenyl)-2-[(5-bromo-2-acetoxybenzylidene)-acetaldehyde-azino]-
thiazole (11)
A solution of 10 (0.01 mol) in acetic anhydride (25 ml) was heated under reflux for
2 h, then cooled and poured into ice-water. The resulting solid was filtered off,
washed with water, dried, and purified by recrystallization from benzene to give 11
as brown crystals, yield 53 %, m.p. 145 °C. IR (KBr): 1,705–1,689 (br.CO), 1,632
(C=N), 1,605, 1,585 (C=C), 1,225, 1,095 (C–O) cm-1. 1H-NMR (DMSO-d6): d 2.31
(s, 3H, COCH3), 2.61 (s, 3H, OCOCH3), 3,89 (s, 3H, OCH3), 6.91–7.81 (m, 9H, Ar–
H and H-thiazole), 8.21 (s, 1H, CH=N) ppm. MS: m/z (%) = 489 (M??2, 9.10),
488 (M??1, 10.80), 487 (M?, 12.50), 486 (10.20), 485 (11.40), 484 (13.60), 483
(25.00), 482 (26.10), 481 (13.60), 480 (14.80), 468 (13.10), 467 (11.40), 466
(21.00), 465 (14.30), 464 (13.10), 447 (13.60), 446 (23.30), 445 (35.80), 444
(26.10), 405 (24.40), 404 (10.80), 403 (27.30), 402 (7.40), 388 (34.70), 387 (24.50),
386 (42.60), 385 (30.10), 286 (27.80), 285 (22.70), 284 (36.90), 271 (14.20), 269
(14.20), 268 (11.90), 242 (4.50), 241 (10.80), 233 (8.00), 232 (13.60), 103 (11.40),
102 (13.60), 97 (11.40), 94 (10.80), 92 (19.90), 91 (27.80), 90 (19.90), 89 (14.30),
77 (33.00), 76 (31.30), 75 (32.40), 74 (13.10), 65 (15.20), 64 (22.70), 63 (47.70), 62
(24.40), 60 (29.50), 59 (13.10), 57 (15.90), 53 (16.50), 51 (20.50), 50 (28.40). Anal.
Found: C, 51.57; H, 3.48; N, 8.45; S, 6.37. C21H18N3BrO4S requires: C, 51, 75; H,
3.69, N, 8.62; S, 6.57.
Results and discussion
Chemistry
The synthetic pathways leading to the new pyrimidine and thiazole derivatives are
illustrated in Scheme 1. Condensation of 5-bromo-2-hydroxybenzaldehyde and
3-nitrobenzaldehyde with ethyl cyanoacetate in presence of anhydrous potassium
carbonate yielded the corresponding ethyl b-aryl-a-cyanoacrylate (2a, b). Treat-
ment [9] of compound 2 with thiourea in the presence of anhydrous potassium
carbonate in methanol under reflux resulted in the formation of 6-aryl-5-cyano-4-
hydroxy-2-mercaptopyrimidine (3a, b).
Acetylation of 6-(5-bromo-2-hydroxyphenyl)-5-cyano-4-hydroxy-2-mercapto-
pyrimidine (3a) with acetic anhydride under reflux led to the formation of
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Synthesis of some nitrogen heterocycles and their in vitro evaluation
R2
CHO
SH
NH2
O
N
N
R1
CH2COOEt
K2CO3/MeOH
Br
S
CN
R2
CN
HN
R1
CN
OEt
X
R2
OH
OH
NH2NHC(S)NH2
K2CO3/MeOH
NH2C(S)NH2
K2CO3/MeOH
8
CN
O
R1
2
3
a,R1 = OH , R2 = Br
b,R1 = H , R2 = NO2
a, R1=OH , R2= Br
b,R1=H ,R2=NO2
NH2
Br
N
H
eO
/M
3
CO
K2
3a
AC2O
N
H
HS
S
NH2C(NH)NH2
OH
N
N
9
Br
ACONa/ACOH
CH3O-Ph-COCH2Br
OH
NH2
CN
OCOCH3
OCH3
Br
N
N
ClCH2COOEt
4
OH
S
CN
NH
N
N
N
OH
5
NO2
10
O
N
N
AC2O
AC2O
NHCOCH3
N
OH
Br
OCH3
CN
N
S
NO2
OH
7
N
CN
N
N
OCOCH3
COCH3
NO2
11
6
Scheme 1 Representations of new reactions performed in the laboratory
6-(5-bromo-2-acetoxyphenyl)-5-cyano-4-hydroxy-2-mercaptopyrimidine (4). Cy-
clocondensation [10] of ethyl-b-(3-nitrophenyl)-a-cyanoacrylate (2b) with guani-
dine hydrochloride in the presence of anhydrous potassium carbonate in methanol
under reflux afforded the corresponding 6-(3-nitrophenyl)-5-cyano-4-hydroxy-2-
aminopyrimidine
(5).
6-(3-Nitrophenyl)-5-cyano-4-hydroxy-2-(acetylamino)-
pyrimidine (6) was prepared via acetylation of 5 with acetic anhydride under reflux.
The reaction of 2-aminopyrimidine (5) with ethyl chloroacetate in presence of
fused sodium acetate in acetic acid under reflux gave the corresponding 7-(3-
nitrophenyl)-6-cyano-5-hydroxy-imidazolo[2,1-b]-pyrimidine-1-one (7).
Treatment [11] of ethyl-b-(5-bromo-2-hydroxyphenyl)-a-cyanoacrylate (2a) with
thiosemicarbazide in presence of anhydrous potassium carbonate in methanol under
reflux gave the corresponding 5-bromo-hydroxybenzaldehyde thiosemicarbazone
(9), which does not give the expected product 8 (Scheme 1). 5-(p-Methoxyphenyl)-
2-[(5-bromo-2-hydroxybenzylidene)-hydrazino]-thiazole (10) was prepared from
the reaction of (5-bromo-2-hydroxy)benzaldehyde thiosemicarbazone (9) with
4-methoxy phenacyl bromide in presence of fused sodium acetate. Acetylation
of thiazole derivative 10 with acetic anhydride under reflux led to the formation of
5(p-methoxyphenyl)-2-[(5-bromo-2-acetoxybenzylidene)-acetylhydrazino]-thiazole
(11) (Scheme 1).
123

J. A. Hasanen et al.
Mass spectrometry
The mass-spectral decomposition modes [12, 13] of the prepared heterocyclic
compounds containing pyrimidine and thiazole ring were investigated. The mass
spectra of the pyrimidine derivatives (3a, b, 4, 5, and 6) showed intense molecular
ion peaks at m/z 323, 274, 365, 257, and 299, consistent with the molecular
formulae C11H6N3BrO2S, C11H6N4O3S and C13H8N3BrO3S, C11H7N5O3, and
C13H9N5O4, respectively.
The molecular ion of compound 5 (Fig. 1) underwent fragmentation to produce a
peak at m/z 215 by losing a NH2CN group. The loss of the formyl group (CHO)
from the ion with m/z 215 resulted in an ion at m/z 186. The ion of m/z 186 broke to
give an ion of m/z 148. The ion of m/z 148 fragmented to give an ion at m/z 102,
which lost a nitro group (NO2). The ion of m/z 102 underwent loss of HCN and
C2H2 molecules to give peaks at m/z 76 and 50, respectively. Furthermore, the
molecular ion of compound 5 (m/z 257) underwent the loss of NH=C=N to give a
peak at m/z 216. Loss of the isocyanate group (NCO) from the ion at m/z 216 gave a
peak at m/z 174. It further lost NO2, C2HCN, and acetylene molecules to give peaks
at m/z 128, 77, and 51, respectively.
From the mass spectrum of compound 6 (Fig. 2), it was concluded that the
molecular ion was at m/z 299. The ion of m/z 299 underwent fragmentation to
produce a peak at m/z 257 by losing a ketene molecule (CH2=C=O) corresponding
to the base peak and the molecular ion of compound 5. The stable fragment of
m/z 257 further broke down via a pathway similar to that of compound 5 (Scheme 2).
The mass spectra of thiazole derivatives 10 and 11 (Figs. 3, 4) are fully
consistent with the assigned structures. In most cases, intense molecular ion peaks
were observed. Thus, compounds 10 and 11 showed intense molecular ion peaks at
m/z 403/405 and 487/489, consistent with the molecular formulae C17H14N3BrO2S
and C21H18N3BrO4S, respectively. The M ? 2 peak was also observed along with
the molecular ion peak due to the presence of isotopes of a bromine atom present in
these compounds.
The molecular ion of compound 10 (Scheme 3) underwent fragmentation to
produce a peak at m/z 206, corresponding to the molecular ion of 5-(4-
methoxyphenyl)-2-aminothiazole. The loss of an amino cyanide (NH2CN) group
from the ion with m/z 206 resulted in an ion at m/z 164. It further underwent the loss
of sulfur atom (S), formaldehyde (CH2O), C2H, and C2H2 to give peaks at m/z 132,
102, 77, and 51, respectively.
Fig. 1 70 eV mass spectrum of compound 5
123

Synthesis of some nitrogen heterocycles and their in vitro evaluation
Fig. 2 70 eV mass spectrum of compound 6
NHCOCH3
N
N
O2N
OH
CN
m/z 299 (28.60%)
-CH2=C=O
NH2
N
NH
O
O2N
CN
m/z 257 (100%)
5
-NH=C=N
-NH2CN
+.
O
C NH
O
CH
HN
C
CN
O2N
CN
O2N
m/z 216 (21.20%)
-NCO
m/z 215 (48.50%)
-CHO
+.
CH CH CN
O2N
N
+
CN
O2N
m/z 186 (17.90%)
m/z 174 (53.60%)
-C2N
-NO2
+.
+.
CN
O2N
CH CHCN
m/z 148 (18.20%)
m/z 128 (57.10%)
-NO2
-CHC-CN
CN
m/z (45.50%)
-HCN
m/z 77(33.30%)
+.
-C2H2
m/z 76 (54.50%)
-C2H2
m/z 51 (60.74%)
+.
m/z 50 (67.90%)
Scheme 2 Main fragmentation pathway of compounds 5 and 6
123

J. A. Hasanen et al.
Fig. 3 70 eV mass spectrum of compound 10
Fig. 4 70 eV mass spectrum of compound 11
The molecular ion of compound 10 was also found to undergo fragmentation to
produce the ion of 2-cyano-4-bromophenol at m/z 197. The ion at m/z 197
underwent loss of bromine atom (Br), formyl group (CHO), and acetylene molecule
(C2H2) to give peaks at m/z 118, 89, and 63, respectively. The loss of the ketene
molecules (CH2CO) from the molecular ion of compound 11 resulted in an ion at
m/z 445. The ion at m/z 445 underwent loss of the ketene molecules (CH2=C=O) to
give the ion at m/z 403, corresponding to the molecular ion of compound 10. The
fragment ion of m/z 403 further broke down via a pathway similar to that of
compound 10. Base peaks at m/z 63 and 206 were found in the mass spectra of
compounds 10 and 11.
Biological assays
Antimicrobial activity
The antimicrobial activities of the synthesized compounds 3, 5, 10, and 11 were
determined by agar well diffusion method [13, 14]. The compounds were evaluated
for antibacterial activity against Bacillus subtilis (RCMBOO107) and Streptococcus
pneumonia (RCMBOO105) as Gram-positive bacteria, and Escherichia coli
(RCMBO-O103) and Pseudomonas sp. (ATCC9027) as Gram-negative bacteria.
Antifungal [15] activity was evaluated against Aspergillus niger and Penicillium
sp. as fungi. The antibiotic streptomycin and clotrimazole were used as reference
drug for antibacterial and antifungal activity, respectively. Dimethylsulfoxide (1 %,
DMSO) was used as control without compound.
All compounds were tested at 10, 50, and 100 mg concentration. The zone of
inhibition was measured in mm and compared with standard drug. The data are
summarized in Table 1, showing that all compounds display certain antimicrobial
activity.
In comparison with standard antibacterial streptomycin and antifungal clotrim-
azole, compounds 5, 10, and 11 were found to be highly active against bacteria and
fungi. Compounds 3a and 3b were also found to be active against bacteria and
fungi.
123

Synthesis of some nitrogen heterocycles and their in vitro evaluation
+.
Scheme 3 Main fragmentation
pathway of compounds 10 and
11
OCH3
S
Br
N
N
N
COCH3
OCOCH3
m/z 487 (12.50%)
11
-CH2=C=O
+.
OCH3
H3COC
S
Br
N
N
N
OH
m/z 445 (35.80%)
-CH2=C=O
+.
S
OCH3
Br
N
N
H
N
OH
m/z 403 (27.30%)
+.
+.
OCH3
CN
OH
Br
S
H2
N
N
m/z 206 (100%)
-NH2CN
m/z 197 (12.50%)
-Br
CN
+.
S
OH
OH3
C
m/z 118 (13.00%)
m/z 164 (88.10%)
CHO
-S
+.
+.
CN
OH3C
m/z 89 (37.00%)
-C2H2
C
C
H
m/z 132 (19.30%)
+.
-CH2O
C
CN
C
+.
m/z 63 (100%)
C
C
H
m/z 102 (13.0%)
-C2H
m/z 77 (33.00%)
-C2H2
m/z 51 (20.30%)
123

J. A. Hasanen et al.
123

Synthesis of some nitrogen heterocycles and their in vitro evaluation
Anticancer activity
Cytotoxic and antitumor activity of prepared compounds 3–11 were evaluated
against cell lines MCF-7, HePG-2, and HCT according to the method of Mosmann
and Vijayan et al. [16]. The drug vinblastine was used as standard.
Inhibitory activity against breast carcinoma cells (MCF-7 cell line), hepatocel-
lular carcinoma cells (HePG-2 cell line), and colon carcinoma cells (HCT cell line)
was tested by using different concentrations of the samples (50, 25, 12.50, 6.25,
3.125, and 1.56 lgm), and cell viability (%) was determined by colorimetric
method.
The 50 % inhibitory concentration (IC50) of the MCF-7 cell line was calculated
from Table 2 and Figs. 5 and 6.
The 50 % inhibitory concentration (IC50) of the HePG-2 cell line was calculated
from Table 3 and Figs. 7 and 8.
Table 2 Evaluation of cytotoxicity of prepared compounds against cell line MCF-7
Sample conc. (lg) Viability (%)
3a
3b
4
5
6
10
11
Vinblastine
standard
50
67.82
40.65
93.14
41.94
65.29
81.76
63.62
94.15
97.82
74.94
69.12
7.82
15.18
29.60
48.75
60.35
76.24
100
25
82.94
93.56
59.21 100
73.03 100
89.26 100
97.42 100
93.15
98.46
80.41
98.50
12.5
6.25
3.125
1.56
0
100
94.09 100
99.65 100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
MCF-7
120
100
80
60
40
20
0
comp 4
comp 3a
comp 5
comp 3b
viblastin standard
0
5
10
15
20
25
30
35
40
45
50
Concentration (µg)
Fig. 5 Evaluation of cytotoxicity of prepared compounds 4, 3a, 5, 3b against MCF-7 cell line
123

J. A. Hasanen et al.
120
100
80
60
40
20
0
comp 10
comp 11
comp 6
vinblastin standard
0
5
10
15
20
25
30
35
40
45
50
Concentration (µg)
Fig. 6 Evaluation of cytotoxicity of prepared compounds 10, 11, 6 against MCF-7 cell line
Table 3 Evaluation of cytotoxicity of prepared compounds against cell line HePG-2
Sample conc. (lg) Viability (%)
3a
3b
4
5
6
10
11
Vinblastine
standard
50
59.68
29.64
95.86
31.34
62.90
81.65
92.19
98.88
25.67
69.15
87.05
82.14
62.54
14.38
16.13
24.25
45.13
55.00
72.13
100
25
74.66
91.42
97.74
73.93 100
84.55 100
92.85 100
95.54 100
99.11 100
93.52
98.66
86.44
97.18
12.50
6.25
3.125
1.56
0
93.75 100
99.29 100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
HePG 2
120
100
80
60
40
20
0
comp 4
comp 3a
comp 5
comp 3b
vinblstin standard
40 45 50
0
5
10
15
20
25
30
35
Concentration (µg)
Fig. 7 Evaluation of cytotoxicity of prepared compounds 3a, 3b, 4, 5 against HePG-2 cell line
123

Synthesis of some nitrogen heterocycles and their in vitro evaluation
120
100
80
60
40
20
0
comp 10
comp 11
comp 6
vinblastin standard
0
5
10
15
20
25
30
35
40
45
50
Concentration (µg)
Fig. 8 Evaluation of cytotoxicity of prepared compounds 6, 10, 11 against HePG-2 cell line
Table 4 Evaluation of cytotoxicity of compounds 3 and 5 against HCT cell line
Sample conc. (lgm)
Viability (%)
3a
3b
36.94
5
Vinblastine standard
50
41.58
78.42
93.65
97.96
100
74.48
91.12
98.66
15.38
23.08
27.35
43.59
53.85
69.23
100
25
69.62
82.14
93.88
98.04
12.5
6.25
3.125
1.56
0
100
100
100
100
100
100
100
100
HCT
120
100
80
60
40
20
0
comp 5
comp 3a
comp 3b
vinblastin standard
0
10
20
30
40
50
Concentration (µg)
Fig. 9 Evaluation of cytotoxicity of compounds 3 and 5 against HCT cell line
123

J. A. Hasanen et al.
Table 5 IC50 (lgm) values of prepared compounds after 72 h continuous exposure of tumor cell lines
Compound
Tumor type/cell line
MCF-7
HePG-2
HCT
3a
[50
[50
41.58
40.98
[50
3b
37.4
38.5
4
Not inhibitory
41.4
Not inhibitory
35.20
36.00
[50
5
–
6
[50
–
10
[50
–
11
[50
[50
–
Vinblastine standard
6.10
4.60
9.80
The IC50 value is the concentration that induces 50 % growth inhibition compared with untreated control
cells
MCF-7 human breast carcinoma cell line
HePG-2 human hepatocellular carcinoma cell line
HCT human colon carcinoma cell line
Also, the 50 % inhibitory concentration (IC50) of the HCT cell line was
calculated from Table 4 and Fig. 9.
The results of 50 % inhibitory concentration (IC50) data are summarized in
Table 5.
In comparison with standard antitumor drug vinblastine, compound 3a was found
to be active against the HCT cell line. Compound 3b was also found to be active
against MCF-7, HePG-2, and HCT cell lines. Compounds 5 and 6 were observed to
be active against MCF-7 and HePG-2 cell lines. As compared with standard
antitumor drug, compounds 10 and 11 were observed to be weakly active against
MCF-7 and HePG-2 cell lines. Compound 4 exhibited no inhibitory active against
MCF-7 and HePG-2 cell lines.
Conclusions
A series of nitrogen heterocycles were synthesized, and their antimicrobial and
anticancer activity was compared with that of a standard drug. Compounds 5, 10,
and 11 were found to exhibit the highest antimicrobial activity. These compounds
showed in vitro growth inhibition activity against MCF-7, HePG-2, and HCT cell
lines that was comparable to or less than that of vinblastine.
Acknowledgments The authors are grateful to Dr. M. Abdelatef and the Regional Center of Mycology
and Biotechnology, Al-Azhar University for their encouragement.
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