1000
N. Ben Hamadi, M. Msaddek / C. R. Chimie 14 (2011) 997–1001
(C-5), 125.40 (C-7), 127.43–136.32 (Carom), 150.15 (C-6),
153.31 (C-3), 200.45 (C-8).
Found: C, 55.89; H, 4.59; N, 8.47%. IR (KBr): C = N 1525;
C = O 1650; NH 3320 cmÀ1 1H-NMR (300 MHz, CDCl3)
d:
.
0.89 (s, 3H, CH3), 1.28 (s, 3H, CH3), 2.41 (s, 3H, CH3), 4.09 (s,
1H, H4), 6.35 (br s, 1H, H1), 6.13; 6.63 (2H, Hfu, J = 3 Hz);
6.69; 7.13 (2H, Hth, J = 3.6 Hz). 13C{1H}NMR (75 MHz,
4.1.2. 2-Pyrazoline (4b)
Yield (0.217 g, 70%), colourless solid. M.p 170–171 8C,
FAB-MS m/z(%): 311 (MH+,100), Anal. Calcd. For
CDCl3)
d: 15.79 (CH3), 22.47 (CH3), 28.99 (CH3), 57.87
C
20H26N2O: C, 77.38; H, 8.44; N, 9.02%; Found: C, 77.30;
H, 8.39; N, 9.08%. IR (KBr): C = N 1550; C = O 1690; NH
3250 cmÀ1. 1H-NMR (300 MHz, CDCl3)
: 0.86 (s, 3H, CH3),
(C-4), 67.93 (C-5), 151.94 (C-3), 108.15–153.65 (Cfu,th),
186.41 (C = O).
d
1.01 (s, 3H, CH3), 1.06 (s, 3H, CH3), 1.32 (s, 3H, CH3), 2.22 (s,
2H, H9), 2.30 (s, 3H, CH3), 2.66 (s, 2H, H11), 3.73 (s, 1H, H4),
5.75 (s, 1H, H7), 5.81 (br s, 2H, H1), 6.85; 7.08 (AA’BB’, 4H,
4.2. Dehydrogenation of 2-Pyrazolines
To a solution of oxalyl chloride (5 equiv) in dry CH2Cl2
(10 mL), at À78 8C under an argon atmosphere, was added
DMSO (7 equiv). The solution was stirred for 15 min, until
effervescence ceased. A solution of the 2-pyrazolines 4a–d
or 6a–d (1 mmol) in dry CH2Cl2 (5 mL) was added
dropwise, and the solution was stirred for 10 min at
À78 8C. Triethylamine (10 equiv) was then added and the
solution was left to warm to 0 8C for 30 min, while stirred.
The reaction mixture was diluted with CH2Cl2 (20 mL) and
washed with saturated aqueous NH4Cl (3 Â 20 mL). The
organic layer was dried (MgSO4) and evaporated, and the
residue was purified by chromatography (SiO2; ethyl
acetate/petroleum ether, 1:4) to afford compounds 7a–d
and 8a–d.
H
arom, J = 8.7 Hz); 13C{1H}NMR (75 MHz, CDCl3)
d: 21.20
(CH3), 22.90 (CH3), 28.30 (CH3), 29.40 (CH3), 33.50 (C-10),
39.00 (C-11), 51.60 (C-9), 59.30 (C-4), 67.30 (C-5), 125.40
(C-7), 128.00–137.00 (Carom), 150.20 (C-6), 153.50 (C-3),
201.01 (C-8).
4.1.3. 2-Pyrazoline (4c)
Yield (0.261 g, 80%), colourless solid. M.p 210–211 8C,
FAB-MS m/z(%): 327 (MH+,100), Anal. Calcd. For
C
20H26N2O2: C, 73.59; H, 8.03; N, 8.58%; Found: C,
73.50; H, 8.11; N, 8.51%. IR (KBr): C = N 1550; C = O
1680; NH 3330 cmÀ1. 1H-NMR (300 MHz, CDCl3)
: 0.75 (s,
d
3H, CH3), 0.93 (s, 3H, CH3), 0.99 (s, 3H, CH3), 1.21 (s, 3H,
CH3), 2.22 (s, 2H, H9), 2.66 (s, 2H, H11), 3.72 (s, 1H, H4), 3.78
(s, 3H, OCH3), 5.76 (s, 1H, H7), 5.80 (br s, 1H, H1), 6.81; 6.88
(AA’BB’, 4H, Harom, J = 9 Hz); 13C{1H}NMR (75 MHz, CDCl3)
4.2.1. Pyrazolenine (7a)
Yield (0.235 g, 80%), colourless solid. Mp 121–122 8C,
Anal. Calcd. For C19H22N2O: C, 77.52; H, 7.53; N, 9.52%;
Found: C, 77.44; H, 7.56; N, 9.45%. IR (KBr): C = C–N = N
d: 22.80 (CH3), 28.00 (CH3), 28.20 (CH3), 29.20 (CH3), 33.30
(C-10), 39.00 (C-11), 51.60 (C-9), 55.19 (OCH3), 58.90 (C-4),
67.30 (C-5), 125.40 (C-7), 114.00–158.90 (Carom), 150.10
(C-6), 153.50 (C-3), 201.20 (C-8).
1615; C = O 1690 cmÀ1
.
1H-NMR (300 MHz, CDCl3)
d
: 0.95
(s, 6H, CH3), 1.25 (s, 6H, CH3), 2.20 (s, 2H, H9), 2.63 (s, 2H,
11), 5.71 (s, 1H, H7), 6.89–7.35 (m, 5H, Harom);
13C{1H}NMR (75 MHz, CDCl3)
20.50 (CH3), 27.62
H
4.1.4. 2-Pyrazoline (4d)
d:
Yield (0.238 g, 70%), colourless solid. M.p 202–203 8C,
FAB-MS m/z(%):342(MH+,100), Anal. Calcd. ForC19H23N3O3:
C, 66.84; H, 6.79; N, 12.31%; Found: C, 66.76; H, 6.82; N,
12.39%. IR (KBr): C = N 1550; C = O 1680; NH 3330 cmÀ1. 1H-
(CH3), 33. 35 (C-10), 38.91 (C-11), 51.51 (C-9), 147.34
(C-4), 163.20 (C-5), 125.37 (C-7), 127.36–136.47 (Carom),
150.14 (C-6), 153.28 (C-3), 201.21 (C-8).
NMR (300 MHz, CDCl3)
0.98(s, 3H, CH3), 1.26(s, 3H, CH3), 2.23(s, 2H, H9), 2.64(s, 2H,
11), 3.70 (s, 1H, H4), 5.78 (s, 1H, H7), 5.81 (br s, 1H, H1), 7.81;
8.12 (AA’BB’, 4H, Harom, J = 8.7 Hz); 13C{1H}NMR (75 MHz,
CDCl3) : 22.81 (CH3), 27.01 (CH3), 28.22 (CH3), 29.16 (CH3),
d
: 0.76 (s, 3H, CH3), 0.94 (s, 3H, CH3),
4.2.2. Pyrazolenine (7b)
Yield (0.277 g, 90%), colourless solid. M.p 110–111 8C,
Anal. Calcd. For C20H24N2O: C, 77.89; H, 7.84; N, 9.08%;
Found: C, 77.91; H, 7.81; N, 9.06%. IR (KBr): C = C–N = N
. d: 0.91
1610; C = O 1690 cmÀ1 1H-NMR (300 MHz, CDCl3)
H
d
33.27 (C-10), 38.50 (C-11), 51.62 (C-9), 58.91 (C-4), 67.29 (C-
5), 125.39 (C-7), 124.10–171.5 (Carom), 150.09 (C-6), 152.97
(C-3), 202.19 (C-8).
(s, 6H, CH3), 1.25 (s, 6H, CH3), 2.31 (s, 3H, CH3), 2.20 (s, 2H,
H9), 2.59 (s, 2H, H11), 5.71 (s, 1H, H7), 6.85; 7.08 (AA’BB’, 4H,
H
arom, J = 8.7 Hz); 13C{1H}NMR (75 MHz, CDCl3)
d: 20.53
(CH3), 21.09 (CH3), 26.98 (CH3), 33.51 (C-10), 38.55 (C-11),
51.61 (C-9), 147.33 (C-4), 162.83 (C-5), 125.40 (C-7),
128.11–138.01 (Carom), 151.13 (C-6), 154.10 (C-3), 200.03
(C-8).
4.1.5. 2-Pyrazoline (6a)
Yield (0.287 g, 85%), yellow solid. M.p 140–141 8C, Anal.
Calcd. ForC15H15ClN2OS2: C, 53.16;H,4.46; N, 8.27%;Found:
C, 53.23; H, 4.35; N, 8.21%. IR (KBr): C = N 1520; C = O 1640;
NH 3300 cmÀ1
.
1H-NMR (300 MHz, CDCl3)
d: 0.87 (s, 3H,
4.2.3. Pyrazolenine (7c)
CH3), 1.29 (s, 3H, CH3), 2.41 (s, 3H, CH3), 4.10 (s, 1H, H4), 6.15
(br s, 1H, H1), 6.67; 7.09 (2H, Hth, J = 3.6 Hz); 6.82; 7.51 (2H,
Hth, J = 3.9 Hz). 13C{1H}NMR (75 MHz, CDCl3)
d: 15.90 (CH3),
22.51 (CH3), 29.02 (CH3), 57.94 (C-4), 68.00 (C-5), 152.55 (C-
3), 125.2–153.04 (Cth), 187.80 (C = O).
Yield (0.275 g, 85%), colourless solid. M.p 123–124 8C,
Anal. Calcd. For C20H24N2O2: C, 74.04; H, 7.46; N, 8.64%;
Found: C, 74.00; H, 7.43; N, 8.71%. IR (KBr): C = C-N = N
1615; C = O 1685 cmÀ1
.
1H-NMR (300 MHz, CDCl3)
d
: 0.88
(s, 6H, CH3), 1.27 (s, 6H, CH3), 2.19 (s, 2H, H9), 2.65 (s, 2H,
11), 5.71 (s, 1H, H7), 3.77 (s, 3H, OCH3), 6.81; 6.88 (AA’BB’,
4H, Harom, J = 9 Hz); 13C{1H}NMR (75 MHz, CDCl3)
: 20.45
H
4.1.6. 2-Pyrazoline (6b)
d
Yield (0.226 g, 70%), yellow solid. M.p 149–150 8C, Anal.
Calcd. For C15H15ClN2O2S: C, 55.81; H, 4.68; N, 8.68%;
(CH3), 26.88 (CH3), 32.91 (C10), 39.13 (C11), 51.58 (C-9),
55.18 (OCH3), 146.11 (C-4), 163.01 (C-5), 125.38 (C-7),