218
H.‐Y. Mao, H. Song, and D.‐Q. Shi
Vol 50
(or phenyl)‐2‐(1H‐1,2,4‐triazol‐1‐yl)‐ethanone (1) with aromatic alde-
hydes in the presence of piperidine according to the literature proce-
dure [11]. 2‐Aryloxyacetohydrazides were synthesized using the
reported method [12]. All of the solvents and materials were reagent
grade and purified as required.
General procedure for the synthesis of 5‐aryl‐1‐
(aryloxyacetyl)‐3‐(tert‐butyl or phenyl)‐4‐(1H‐1,2,4‐triazol‐1‐yl)‐
4,5‐dihydropyrazole 3. 3‐aryl‐1‐t‐butyl (or phenyl)‐2‐(1H‐1,2,
4‐triazol‐1‐yl)prop‐2‐en‐1‐one 2 (2.0 mmol), 2‐aryloxyacetohydrazides
(2.4 mmol), anhydrous ethanol (20 mL) and several drops of glacial
acetic acid were added to a 50 mL three‐necked flask, the mixture was
stirred at room temperature for 6–10 h till the reaction was completed
(monitored by TLC). The solid was filtered and recrystallized by
anhydrous ethanol to give the target compounds 3a–3n in 56–87%
yields.
7.20 (d, J = 9.0 Hz, 2H, ArH), 7.25 (d, J = 9.0 Hz, 2H, ArH), 7.30
(d, J = 8.4 Hz, 2H, ArH), 7.96 (s, 1H, triazole‐H), 8.55 (s, 1H, tria-
zole‐H); IR (KBr) υ: 3115, 2973 (ArH), 1700 (C═O), 1659
(C═N), 1580, 1492, 1368 (Ar), 1273, 1224, 1093 (C─O─C) cm−1;
ESI‐MS m/z (%): 514 (M+K+4, 35), 512 (M+K+2, 100), 510 (M
+K, 40). Anal. calcd for C23H23Cl2N5O2: C 58.48, H 4.91, N
14.83; found C 58.40, H 5.06, N 14.98.
3f (R = t‐butyl, Ar = 4‐ClC6H4, Ar′ = 2,4‐Cl2C6H3): white
crystals, yield: 87%, m.p. 155.5–157.2°C; 1H‐NMR (CDCl3,
600 MHz) δ: 0.83 (s, 9H, 3CH3), 4.40 (AB, J = 14.4 Hz, 2H,
CH2), 4.87 (d, J = 9.6 Hz, 1H, CH), 5.69 (d, J = 9.0 Hz, 1H,
CH), 6.68 (d, J = 8.4 Hz, 1H, ArH), 7.14 (d, J = 8.4 Hz, 1H,
ArH), 7.15 (d, J = 8.4 Hz, 2H, ArH), 7.32 (d, J = 8.4 Hz, 2H,
ArH), 7.61 (s, 1H, ArH), 7.96 (s, 1H, triazole‐H), 8.51 (s, 1H, tria-
zole‐H); IR (KBr) υ: 3128, 2974 (ArH), 1712 (C═O), 1656
3a (R = t‐butyl, Ar = 2,4‐Cl2C6H3, Ar′ = C6H5): white crystals,
yield: 56%, m.p. 141.2–141.5°C; 1H‐NMR (CDCl3, 600 MHz) δ:
1.21 (s, 9H, 3CH3), 4.47 (s, 2H, CH2), 5.23 (d, J = 9.0 Hz, 1H,
CH), 5.96 (d, J = 9.0 Hz, 1H, CH), 6.82 (d, J = 7.8 Hz, 2H,
ArH), 7.02–7.30 (m, 5H, ArH), 7.79(s, 1H, triazole‐H), 7.84 (s,
1H, Ar─H), 8.05 (s, 1H, triazole‐H); IR (KBr) υ: 3071, 2971
(ArH), 1715 (C═O), 1652 (C═N), 1592, 1495, 1477 (Ar),
1218, 1061(C─O─C) cm−1; ESI‐MS m/z (%): 512 (M+K+2,
100), 510 (M+K, 85), 494 (M+Na, 16), 472 (M++1, 8), 347
(26). Anal. calcd for C23H23Cl2N5O2: C 58.48, H 4.91, N
14.83; found C 58.30, H 4.84, N 14.97.
(C═N), 1579, 1477, 1321 (Ar), 1232, 1071 (C─O─C) cm−1
;
ESI‐MS m/z (%): 548 (M+K+4), 546 (M+K, 100), 381 (25),
379 (17). Anal. calcd for C23H22Cl3N5O2: C 54.51, H 4.38, N
13.82; found C 54.71, H 4.44, N 13.69.
3g (R = t‐butyl, Ar = C6H5, Ar′ = C6H5): white solid, yield:
1
75%, m.p. 129.3–131.8°C; H‐NMR (CDCl3, 600 MHz) δ: 0.79
(s, 9H, 3CH3), 4.38 (s, 2H, CH2), 4.86 (d, J = 8.4 Hz, 1H, CH),
5.73 (d, J = 9.0 Hz, 1H, CH), 6.75 (d, J = 8.4 Hz, 2H, ArH),
6.99 (t, J = 8.4 Hz, 1H, ArH), 7.24–7.42 (m, 7H, ArH), 7.96 (s,
1H, triazole‐H), 8.56 (s, 1H, triazole‐H); IR (KBr) υ: 3113,
2971 (ArH), 1705 (C═O), 1655 (C═N), 1582, 1496, 1364 (Ar),
1270, 1226, 1084 (C─O─C) cm−1; ESI‐MS m/z (%): 444 (M+K+2,
35), 442 (M+K, 36), 277 (86). Anal. calcd for C23H25N5O2: C
68.47, H 6.25, N 17.36; found C 68.61, H 6.18, N 17.50.
3b (R = t‐butyl, Ar = 2,4‐Cl2C6H3, Ar′ = 4‐ClC6H4): white solid,
yield: 80%, m.p. 144.6–146.4°C; 1H‐NMR (CDCl3, 600 MHz)
δ: 1.13 (s, 9H, 3CH3), 4.44 (s, 2H, CH2), 5.19 (d, J = 8.4 Hz, 1H,
CH), 5.93 (d, J = 9.0 Hz, 1H, CH), 6.75 (d, J = 8.4 Hz, 2H, ArH),
7.09–7.30 (m, 4H, ArH), 7.76 (s, 1H, triazole‐H), 7.82 (s, 1H,
Ar─H), 8.09 (s, 1H, triazole‐H); IR (KBr) υ: 3123, 2972 (ArH),
1716 (C═O), 1643 (C═N), 1508, 1491, 1368 (Ar), 1276, 1220,
1057(C─O─C) cm−1; ESI‐MS m/z (%): 547.6 (M+K+2, 100), 546
(M+K, 89), 507 (M++2, 8), 505 (5). Anal. calcd for C23H22Cl3N5O2:
C 54.51, H 4.38, N 13.82; found C 54.73, H 4.24, N 13.67.
3h (R = t‐butyl, Ar = C6H5, Ar′ = 4‐ClC6H4): white solid,
1
yield: 74%, m.p. 140.1–141.8°C; H‐NMR (CDCl3, 600 MHz)
δ: 0.80 (s, 9H, 3CH3), 4.36 (s, 2H, CH2), 4.84 (d, J = 8.4 Hz,
1H, CH), 5.73 (d, J = 9.0 Hz, 1H, CH), 6.68 (d, J = 8.4 Hz,
2H, ArH), 7.19 (d, J = 8.4 Hz, 2H, ArH), 7.31–7.36 (m, 5H,
ArH), 7.96 (s, 1H, triazole‐H), 8.62 (s, 1H, triazole‐H); IR
(KBr) υ: 3115, 2977 (ArH), 1699 (C═O), 1655 (C═N), 1582,
1491, 1329 (Ar), 1276, 1221, 1059 (C─O─C) cm−1; ESI‐MS
m/z (%): 479 (88), 477 (M+K+1, 100), 311 (97). Anal. calcd for
C23H24ClN5O2: C 63.08, H 5.52, N 15.99; found C 63.24, H
5.77, N 16.13.
3c (R = t‐butyl, Ar = 2,4‐Cl2C6H3, Ar′ = 2,4‐Cl2C6H3): white crys-
tals, yield: 72%, m.p. 156.1–156.5°C; 1H‐NMR (CDCl3, 600 MHz) δ:
1.15 (s, 9H, 3CH3), 4.50 (s, 2H, CH2), 5.26 (d, J = 9.0 Hz, 1H, CH),
5.94 (d, J = 9.0 Hz, 1H, CH), 6.71 (d, J = 8.4 Hz, 1H, ArH), 7.17
(d, J = 8.4 Hz, 2H, ArH), 7.29 (d, J = 8.4 Hz, 1H, ArH), 7.38 (s,
1H, ArH), 7.80 (s, 1H, triazole‐H), 7.94 (s, 1H, ArH), 8.05 (s, 1H,
triazole‐H); IR (KBr) υ: 3126, 2974 (ArH), 1718 (C═O), 1636
(C═N), 1588, 1476, 1363 (Ar), 1236, 1071(C─O─C) cm−1; ESI‐
MS m/z (%): 582 (M+K+2, 86), 580 (M+K, 100), 543 (M++2, 4),
541 (3). Anal. calcd for C23H21Cl4N5O2: C 51.04, H 3.91, N 12.94;
found C 51.23, H 4.07, N 12.70.
3i (R = t‐butyl, Ar = C6H5, Ar′ = 2,4‐Cl2C6H3): white solid,
1
yield: 67%, m.p. 154.2–155.8°C; H‐NMR (CDCl3, 600 MHz)
δ: 0.79 (s, 9H, 3CH3), 4.40 (AB, J = 15.0 Hz, 2H, CH2), 4.88
(d, J = 9.6 Hz, 1H, CH), 5.74 (d, J = 9.6 Hz, 1H, CH), 6.66 (d,
J = 9.0 Hz, 1H, ArH), 7.12 (d, J = 9.0 Hz, 1H, ArH), 7.28–7.33
(m, 5H, ArH), 7.64 (s, 1H, ArH), 7.96 (s, 1H, triazole‐H), 8.58
(s, 1H, triazole‐H); IR (KBr) υ: 3134, 2972 (ArH), 1720
(C═O), 1652 (C═N), 1531, 1500, 1473, 1348 (Ar), 1292,
1230, 1074 (C─O─C) cm−1; ESI‐MS m/z (%): 512 (M+K+2,
100), 510 (M+K, 26). Anal. calcd for C23H23Cl2N5O2: C 58.48,
H 4.91, N 14.83; found C 58.31, H 4.75, N 14.62.
3d (R = t‐butyl, Ar = 4‐ClC6H4, Ar′ = C6H5): white solid,
1
yield: 78%, m.p. 130.0–131.8°C; H‐NMR (CDCl3, 600 MHz)
δ: 0.84 (s, 9H, 3CH3), 4.40 (s, 2H, CH2), 4.87 (d, J = 9.0 Hz,
1H, CH), 5.69 (d, J = 8.4 Hz, 1H, CH), 6.76 (d, J = 6.6 Hz,
2H, ArH), 7.00 (t, J = 7.2 Hz, 1H, ArH), 7.28–7.41 (m, 6H,
ArH), 7.98 (s, 1H, triazole‐H), 8.60 (s, 1H, triazole‐H); IR
(KBr) υ: 3124, 2972 (ArH), 1715 (C═O), 1639 (C═N), 1586,
1477, 1365 (Ar), 1233, 1067 (C─O─C) cm−1; ESI‐MS m/z
(%): 478 (M+K+1, 89), 437 (M+, 5), 311 (100), 190 (45). Anal.
calcd for C23H24ClN5O2: C 63.08, H 5.52, N 15.99; found C
62.95, H 5.37, N 15.72.
3j (R = t‐butyl, Ar = 4‐CH3OC6H4, Ar′ = 4‐ClC6H4): white
solid, yield: 75%, m.p. 115.8–116.9°C; 1H‐NMR (CDCl3, 600
MHz) δ: 0.80 (s, 9H, 3CH3), 3.73 (s, 3H, CH3O), 4.55 (s, 2H,
CH2), 4.79 (d, J = 9.6 Hz, 1H, CH), 5.69 (d, J = 9.0 Hz, 1H,
CH), 6.68 (d, J = 9.0 Hz, 2H, ArH), 6.84 (d, J = 9.0 Hz, 2H,
ArH), 7.19–7.23 (m, 4H, ArH), 7.95 (s, 1H, triazole‐H), 8.55 (s,
1H, triazole‐H); IR (KBr) υ: 3120, 2967 (ArH), 1717 (C═O),
1681 (C═N), 1631, 1513, 1490 (Ar), 1250, 1218, 1061
(C─O─C) cm−1; ESI‐MS m/z (%): 507.6 (M+K+1, 100), 507
(M+K, 87), 340.6 (52). Anal. calcd for C24H26ClN5O3: C 61.60,
H 5.60, N 14.97; found C 61.73, H 5.66, N 14.82.
3e (R = t‐butyl, Ar = 4‐ClC6H4, Ar′ = 4‐ClC6H4): white crystals,
1
yield: 65%, m.p. 168.1–169.2°C; H‐NMR (CDCl3, 600 MHz) δ:
0.83 (s, 9H, 3CH3), 4.36 (s, 2H, CH2), 4.82 (d, J = 9.0 Hz, 1H,
CH), 5.68 (d, J = 9.0 Hz, 1H, CH), 6.68 (d, J = 9.0 Hz, 2H, ArH),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet