Vol. 31, No. 1 (2019)
Development of 5-(Aryl)-3-phenyl-1H-pyrazole Derivatives as Potent Antimicrobial Compounds 47
(E)-1-(Phenyl)-1-phenylprop-2-en-1-one (3p): 1H NMR:
(CDCl3) δ 8.06 (d, 1H); 7.06 (m, 5H); 7.59 (d, 1H); 7.73 (m,
5H). 13C NMR (CDCl3) δ 189.3, 145.1, 137.9, 135.2, 134.5,
129.2, 128.5, 127.9. Calculated mass for (C15H12O2) 208.8;
Observed 209.5. IR (nujal) cm1: 1646, 1588, 1536.
3,5-Dibromo-2-(3-phenyl-4,5-dihydro-1H-pyrazol-5-
yl)phenol (4g): 1H NMR: (CDCl3) δ 7.67 (s, 1H); 7.52 (m, 5H);
7.02 (s, 1H); 6.67 (m, 1H); 5.55 (s, 1H); 3.91 (d, 2H); 3.88 (t,
1H). 13C NMR (CDCl3) δ 158.4, 157.4, 151.7, 139.1, 136.4,
131.3, 128.8, 128.1, 125.7, 118.3, 42.6, 41.1. Calculated mass
for (C15H13N2OBr) 393.93; Observed 395.04. IR (KBr, cm–1):
3397, 3322, 1634, 1613.
1
(E)-1-(Furan-2-yl)-1-phenylprop-2-en-1-one (3o): H
NMR: (CDCl3) δ 8.17 (d, 1H); 7.9(d, 1H); 7.89 (m, 3H); 7.73
(m, 1H); 7.65 (d, 1H); 6.87 (m, 2H).13C NMR (CDCl3) δ 189.7,
151.7, 143.7, 137.9, 134.5, 129.2, 128.5, 127.3, 113.8, 112.7.
Calculated mass for (C13H10O2) 198.08; Observed 199.05. IR
(nujal) cm1: 1657, 1597, 1551.
5-(4-Fluorophenyl)-3-phenyl-4,5-dihydro-1H-pyrazole
(4h): 1H NMR: (CDCl3) δ 7.54 (m, 5H); 7.27 (m, 4H); 7.03 (s,
13
1H); 3.87 (d, 2H); 3.45 (t, 1H). C NMR (CDCl3) δ 160.9,
151.7, 139.2, 136.7, 131.08, 128.5, 128.2, 114.8, 51.1, 42.6.
Calculated mass for (C17H13N2F) 240.11; Observed 241.25.
IR (KBr, cm–1): 3391, 3322, 1637, 1602.
General procedure for synthesis of 3,4-dihydro-3,5-
disubstituted pyrazoles 4(a-p): The suspension of the corres-
ponding chalcone 3 (440 mg, 2 mmol) and hydrazine hydrate
(1.5 mL, 10 mmol) in ethanol (10 mL) was refluxed for 3 h and
left overnight at room temperature. The solid precipitate formed
was filtered off. The resulting compound obtained was recrysta-
llized from hot ethanol to afford compound 4 as buff crystals.
3-Phenyl-5(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-
pyrazole (4a): 1H NMR: (CDCl3) δ 7.67 (m, 5H); 7.0 (s, 1H);
6.52 (m, 2H); 3.92 (d, 2H); 3.83 (s, 9H); 3.31 (t, 1H). 13C NMR
(CDCl3) δ 152.6, 151.7, 137.2, 136.4, 128.8, 102.2, 56.1, 51.7,
42.4. Calculated mass for (C18H20N2O3) 312.15; Observed
313.25. IR (KBr, cm–1): 3391, 3322, 1632, 1603.
5-(3-Nitrophenyl)-3-phenyl-4,5-dihydro-1H-pyrazole
1
(4i): H NMR: (CDCl3) δ 8.18 (m, 2H); 7.68 (m, 2H); 7.52
(m, 5H); 3.87 (d, 2H); 3.45 (t, 1H). 13C NMR (CDCl3) δ, 151.17,
147.4, 144.4, 136.4, 133.8, 131.02, 129.4, 128.2, 1124.8, 50.9,
42.4. Calculated mass for (C15H13N3FO2) 267.28; Observed
268.12. IR (KBr, cm–1): 3398, 3325, 1637, 1602.
5-(4-Chlorophenyl)-3-phenyl-4,5-dihydro-1H-pyra-
1
zole (4j): H NMR: (CDCl3) δ 7.54 (m, 5H); 7.27 (m, 4H);
7.03 (s, 1H); 3.87 (d, 2H); 3.45 (t, 1H). 13C NMR (CDCl3) δ
151.7, 136.4, 132.3, 131.12, 128.6, 127.4, 114.8, 51.4, 41.9.
Calculated mass for (C15H13N2Cl) 256.73; Observed 256.81.
IR (KBr, cm–1): 3396, 3323, 1639, 1605.
5-(3,5,-Dimethoxyphenyl)-3-phenyl-4,5-dihydro-1H-
1
pyrazole (4b): H NMR: (CDCl3) δ 7.52 (m, 5H); 6.96 (s,
5-(4-tert-Butylphenyl)-3-phenyl-4,5-dihydro-1H-
1
1H); 6.52 (m, 32H); 3.94 (d, 2H); 3.81 (s, 6H); 3.43 (t, 1H).
13C NMR (CDCl3) δ 151.7, 147.8, 136.8, 136.2, 131.1, 128.8,
121.2, 118.9, 56.3, 51.4, 42.8. Calculated mass for (C17H18N2O2)
282.14; Observed 283.21. IR (KBr, cm–1): 3391, 3322, 1632,
1603.
pyrazole (4k): H NMR: (CDCl3) δ 7.52 (m, 5H); 7.21 (m,
4H); 7.03 (s, 1H); 3.94 (d, 2H); 3.63 (t, 1H) 1.35 (s, 9H). 13C
NMR (CDCl3) δ 151.7, 149.3, 140.4, 136.4, 131.3, 131.12,
128.6, 125.4, 51.5, 43.1, 34.2, 31.3. Calculated mass for
(C19H22N2) 278.18; Observed 279.22. IR (KBr, cm–1): 3399,
3322, 1638, 1606.
5-(3,4-Dimethoxyphenyl)-3-phenyl-4,5-dihydro-1H-
pyrazole (4c): 1H NMR: (CDCl3) δ 7.52 (m, 5H); 7.1 (s, 1H);
6.63 (m, 3H); 3.94 (d, 2H); 3.81 (s, 6H); 3.33 (t, 1H). 13C NMR
(CDCl3) δ 161.4, 151.5, 145.5, 137.2, 136.4, 128.8, 128.2,
104.3, 55.8, 51.3, 42.6. Calculated mass for (C17H18N2O2)
282.14; Observed 283.18. IR (KBr, cm–1): 3398, 3332, 1635,
1609.
2-(3-Phenyl-4,5-dihydro-1H-pyrazol-5yl)-pyridine
(4l): 1H NMR: (CDCl3) δ 8.46 (m, 1H); 7.55 (m, 5H); 7.49 (m,
3H); 7.05 (s, 1H); 3.92 (d, 2H); 3.73 (t, 1H). 13C NMR (CDCl3)
δ 152.2, 151.7, 144.4, 136.4, 131.0, 128.8, 127.9, 121.0, 51.2,
42.6. Calculated mass for (C14H13N3) 223.11; Observed 224.18.
IR (KBr, cm–1): 3392, 3324, 1631, 1604.
2-Methoxy-6-(3-phenyl-4,5-dihydro-1H-pyrazol-5-
yl)phenol (4d): H NMR: (CDCl3) δ 7.67 (m, 5H); 7.0 (s,
3-(3-Phenyl-4,5-dihydro-1H-pyrazol-5yl)-pyridine
1
(4m): 1H NMR: (CDCl3) δ 7.66 (m, 1H); 7.52 (m, 5H); 7.43
13
1H); 6.68 (m, 3H); 5.35 (s, 1H); 3.93 (d, 2H); 3.81 (s, 3H);
3.43 (t, 1H). 13C NMR (CDCl3) δ 151.7, 147.8, 143.5, 139.2,
131.1, 128.8, 118.2, 51.5, 42.9. Calculated mass for
(C16H16N2O2) 268.15; Observed 269.19. IR (KBr, cm–1): 3392,
3323, 1636, 1606.
2-(3-Phenyl-4,5-dihydro-1H-pyrazol-5-yl)phenol (4e):
1H NMR: (CDCl3) δ 7.52 (m, 5H); 7.12 (m, 4H); 6.98 (s, 1H);
5.37 (s, 1H); 3.95 (d, 2H); 3.38 (t, 1H). 13C NMR (CDCl3) δ
154.1, 151.3, 137.4, 131.2, 130.9, 128.6, 126.2, 121.1, 115.7,
44.5, 42.9. Calculated mass for (C15H14N2O) 238.11; Observed
239.16. IR (KBr, cm–1): 3399, 3328, 1642, 1613.
(m, 3H); 7.15 (s, 1H); 3.88 (d, 2H); 4.13 (t, 1H). C NMR
(CDCl3) δ 151.7, 143.2, 136.5, 131.3, 127.8, 126.9, 121.5,
52.2, 41.9. Calculated mass for (C14H13N3) 223.11; Observed
224.15. IR (KBr, cm–1): 3394, 3328, 1637, 1601.
4-(3-Phenyl-4,5-dihydro-1H-pyrazol-5yl)-pyridine
(4n): 1H NMR: (CDCl3) δ 8.15 (d, 2H); 7.56 (m, 5H); 7.35 (d,
2H); 7.05 (s, 1H); 3.94 (d, 2H); 3.83 (t, 1H). 13C NMR (CDCl3)
δ 152.6, 149.7, 149.4, 136.6, 128.3, 128.1, 123.9, 123.0, 51.1,
42.8. Calculated mass for (C14H13N3) 223.11; Observed 224.14.
IR (KBr, cm–1): 3396, 3323, 1634, 1605.
5-(Furan-2-yl)3-phenyl-4,5-dihydro-1H-pyrazole (4o):
2-Bromo-3-(3-phenyl-4,5-dihydro-1H-pyrazol-5-
1H NMR: (CDCl3) δ 7.52 (m, 5H); 6.43 (m, 3H); 7.15 (s, 1H);
1
13
yl)phenol (4f): H NMR: (CDCl3) δ 7.67 (m, 5H); 7.08 (s,
3.94 (d, 2H); 4.1 (t, 1H). C NMR (CDCl3) δ 152.4, 151.4,
1H); 6.72 (m, 3H); 5.35 (s, 1H); 3.94 (d, 2H); 3.91 (t, 1H). 13C
NMR (CDCl3) δ 156.4, 151.7, 147.1, 136.4, 131.1, 128.9, 128.2,
121.7, 114.3, 47.6, 41.9. Calculated mass for (C15H13N2OBr)
316.02; Observed 317.14. IR (KBr, cm–1): 3393, 3326, 1633,
1605.
141.5, 136.4, 131.0, 128.8, 128.2, 111.0, 109.2, 50.8, 43.7.
Calculated mass for (C13H12N2O) 212.19; Observed 213.27.
IR (KBr, cm–1): 3396, 3324, 16323, 1601.
3,5-Diphenyl-4,5-dihydro-1H-pyrazole (4p): 1H NMR:
(CDCl3) δ 7.52 (m, 5H); 7.29 (m, 5H); 7.03 (s, 1H); 3.91 (d,