PHUNGPIS et al., Orient. J. Chem., Vol. 30(3), 933-939 (2014)
935
2- and 6-H), 7.45 (2H, d, J = 8.0 Hz, 3- and 5-H),
7.18–7.23 (6H, m, ArH) 7.04 (1H, s, CH), 2.40 (3H,
s, Ar-CH3), 2.35 (3H, s, Ar-CH3), 2.32 (3H, s, Ar-CH3);
13C NMR (CDCl3) d: 21.2, 21.6, 21.7, 77.6, 126.8,
128.6, 129.0, 129.1, 129.3, 129.8, 130.0, 131.2,
132.2, 139.2, 144.0, 144.3, 166.1, 193.4.
layers were combined and washed with water and
dried with Na2SO4 and concentrated under reduced
pressure.The residue was purified using preparative
thin layer chromatography on silica gel with CH2Cl2
as eluant.
The purified compounds (6a-c, 8a-c, 9d
and 10d) with their physical data are listed below.
O-(4-Chlorobenzoyl)-4,4/-dichlorobenzoin
(4c). Yellow crystals; mp 125–127 °C (lit.10 127–128
°C). FTIR (KBr, n, cm-1): 3095 (aromatic C-H
stretching), 2925 (aliphatic C-H stretching), 1722,
1698 (C=O stretching), 1592 (aromatic C=C
stretching), 1249, 1090 (C-O stretching), 757 (C-Cl
stretching). 1H NMR (CDCl3, 400 MHz) δ: 7.95 (2H,
d, J = 8.8 Hz, 2"- and 6"-H), 7.82 (2H, d, J = 8.4 Hz,
2- and 6-H), 7.29-7.41 (8H, m, ArH), 6.91 (1H, s,
CH); 13C NMR d 77.1, 127.5, 128.9, 129.2, 129.6,
129.9, 130.1, 131.3, 131.7, 132.7, 135.8, 140.1,
140.4, 165.0, 192.1.
4-Phenyl-4-oxobutanenitrile (6a). White
crystals;mp 75-77 oC (lit.12 76 oC).FTIR (KBr, n, cm-1):
3067 (aromatic C-H stretching), 2923, 2882 (aliphatic
C-H stretching), 2252 (Ca”N stretching), 1673 (C=O
stretching), 1604 (aromatic C=C stretching).1H NMR
δ 7.96 (2H, d, J = 7.2 Hz, 2'- and 6'-H), 7.62 (1H, t, J
= 7.6 Hz, 4'-H), 7.50 (2H, t, J = 7.6 Hz, 3'- and 5'-H),
3.39 (2H, t, J = 7.2 Hz, CH2CH2CN), 2.78 (2H, t, J =
7.2 Hz, CH2CH2CN); 13C NMR d 11.8, 34.2, 119.2,
128.0, 128.8, 133.9, 135.6, 195.3.
O-(4-Fluorobenzoyl)-4,4/-difluorobenzoin
(4d). Yellow liquid; IR (KBr, n, cm-1): 3082 (aromatic
C-H stretching), 2926 (aliphatic C-H stretching),
1724, 1687 (C=O stretching), 1601, 1508 (aromatic
C=C stretching), 1285, 1154 (C-O stretching), 1106
(C-F stretching).1H NMR (CDCl3, 400 MHz) δ: 8.12
(2H, dd, J = 8.8 and 5.2 Hz, 2"- and 6"-H), 8.01 (2H,
dd, J = 8.8 and 5.2 Hz, 2- and 6-H), 7.54 (2H, dd,
J = 8.8 and 5.2 Hz, 2'- and 6'-H), 7.08-7.14 (6H,
m, ArH), 7.02 (1H, s, CH); 13C NMR d 76.7, 115.6,
115.8, 116.0, 116.2, 116.3, 116.5, 125.4, 128.5,
129.4, 130.2, 130.6, 130.7, 130.9, 131.0, 131.5,
131.6, 132.6, 132.7, 162.1, 164.6, 164.7, 164.9,
166.0, 167.3, 167.4, 192.0.
4-(4/-Tolyl)-4-oxobutanenitrile (6b). White
crystals;mp 75-77 oC (lit.13 75 oC).FTIR (KBr, n, cm-1):
3040 (aromatic C-H stretching), 2924, 2853 (aliphatic
C-H stretching), 2251(Ca”N stretching), 1673 (C=O
stretching), 1606 (aromatic C=C stretching). 1H NMR
δ 7.86 (2H, d, J = 8.0 Hz, 2'- and 6'-H), 7.29 (2H,
d, J = 8.0 Hz, 3'- and 5'-H), 3.37 (2H, t, J = 7.2 Hz,
CH2CH2CN), 2.77 (2H, t, J = 7.2 Hz, CH2CH2CN),
2.43 (3H, s, Ar-CH3); 13C NMR d 11.8, 29.7, 34.1,
119.2, 128.1, 129.5, 133.2, 144.9, 201.4.
4-(4/-Chlorophenyl)-4-oxobutanenitrile
o
o
(6c). White crystals; mp 70-72 C (lit.14 72-73 C).
FTIR (KBr, n, cm-1): 3091, 3060 (aromatic C-H
stretching), 2924 (aliphatic C-H stretching), 2250
(Ca”N stretching), 1675 (C=O stretching), 1590
(aromatic C=C stretching), 772 (C-Cl stretching). 1H
NMR δ 7.89 (2H, d, J = 8.4 Hz, 2''- and 6'-H), 7.47
(2H, d, J = 8.4 Hz, 3'- and 5'-H), 3.35 (2H, t, J = 7.2
Hz, CH2CH2CN), 2.77 (2H, t, J = 7.2 Hz, CH2CH2CN);
13C NMR d 11.7, 34.2, 119.0, 129.2, 129.4, 133.9,
140.5, 194.1.
General procedure for Stetter reaction between
either acryonitrile (5) or ethyl acrylate (7)
and aromatic aldehydes catalysed by N,N-
dimethylbenzimidazolium iodide (2) in [bmim]
[OH]
To
a stirred solution of N, N-
dimethylbenzimidazolium iodide (2) (0.055 g,
0.20 mmol) in [bmim][OH] (2 ml) was added either
acryonitrile (5) or ethyl acrylate (7) (2.00 mmol)
and an aromatic aldehyde (1.00 mmol) at room
temperature. The temperature was raised to 80 °C
and the resulting mixture was allowed to stir for 14–
17 h.After completion of the reaction, as determined
by TLC (100% CH2Cl2), the reaction mixture was
extracted with ethyl acetate (3x80 ml). The organic
Ethyl 4-phenyl -4-oxobutanoate (8a).Yellow
liquid. FTIR (neat, n, cm-1): 3063 (aromatic C-H
stretching), 2983, 2933 (aliphatic C-H stretching),
1733, 1687(C=O stretching), 1597 (aromatic C=C
stretching), 1219, 1031 (C-O stretching). 1H NMR
δ 7.97 (2H, d, J = 7.2 Hz, 2'- and 6'-H), 7.55 (1H,
t, J = 7.2 Hz, 4'-H), 7.45 (2H, t, J = 7.2 Hz, 3'- and