Table 4 (Contd.)
Entry
l
Aldehyde
Product
mp (◦C)
52–54
Lit. mp (◦C)
53–54
Ref.
42
Yield (%)b
99
m
n
86–88
84–86
85
16
38
99
95
82–83
a Reactions were carried out with aldehyde (10 mmol) and ethyl cyanoacetate (10 mmol) in the presence of PANPF-3 (0.500 g, containing 1.45 mmol
tertiary amine group) in ethanol (20 mL) under reflux for 1.5 h. b Isolated yield after column chromatograph.
temperature and the reaction time decreased to 1 h to give
the condensation products in yields ranging from 92% to 99%
(Table 5).
Selected data for typical compounds are given below.
Ethyl (E)-2-cyano-3-phenyl-2-p◦ropenoate (Table 4, entry a).
White solid, melting point 47–48 C, 1H NMR (CDCl3): d 8.25
(s, 1H, CH), 7.99 (d, 2H, J = 7.3 Hz, ArH), 7.56 (t, 1H, J =
7.3 Hz, ArH), 7.51 (t, 2H, J = 7.3 Hz, ArH), 4.39 (q, 2H, J =
7.1 Hz, CH2), 1.40 (t, 3H, J = 7.1 Hz, CH3).
Ethyl (E)-2-cyano-3-(2-furyl)-2-propenoate (Table 4, entry n).
Deep yellow solid, melting point 84–86 ◦C, 1H NMR (CDCl3):
d 8.02 (s, 1H, CH), 7.76 (d, 1H, J = 1.5 Hz), 7.40 (d, 1H, J =
3.7 Hz), 6.67 (dd, 1H, J1 = 1.7 Hz, J2 = 3.6 Hz), 4.36 (q, 2H, J =
7.1 Hz, CH2), 1.38 (t, 3H, J = 7.1 Hz, CH3).
2-(Phenylmethylene)malononitrile (Table 5, entry a). White
◦
1
solid, melting point 80–81 C, H NMR (CDCl3): d 7.91 (d,
2H, J = 7.5 Hz, ArH), 7.78 (s, 1H, CH), 7.64 (t, 1H, J = 7.4 Hz,
ArH), 7.54 (t, 2H, J = 7.7 Hz, ArH).
Ethyl (E)-2-cyano-3-(4-hydroxyphenyl)-2-propenoate (Table 4,
entry d). Yellow solid, melting point 170–171 ◦C, 1H NMR
(DMSO-d6): d 8.24 (s, 1H, CH), 8.00 (d, 2H, J = 8.8 Hz, ArH),
6.96 (d, 2H, J = 8.8 Hz, ArH), 4.29 (q, 2H, J = 7.1 Hz, CH2),
3.39 (s, 1H, OH), 1.30 (t, 3H, J = 7.1 Hz, CH3).
Ethyl (E)-2-cyano-3-(4-dimethylaminophenyl)-2-propenoate
(Table 4, entry f). Orange solid, melting point 118–120 ◦C,
1H NMR (CDCl3): d 8.06 (s, 1H, CH), 7.93 (d, 2H, J =
8.2 Hz, ArH), 6.68 (d, 2H, J = 8.4 Hz, ArH), 4.33 (q, 2H, J =
7.1 Hz, CH2), 3.10 (s, 6H, NCH3), 1.37 (t, 3H, J = 7.1 Hz,
CH3).
Ethyl (E)-2-cyano-3-(2-trifluoromethylphenyl)-2-propenoate
(Table 4, entry g). White solid, melting point 74–75 ◦C, 1H
NMR (CDCl3): d 8.65 (d, 1H, J = 1.8 Hz, CH), 8.12 (d, 1H, J =
7.7 Hz, ArH), 7.80 (d, 1H, J = 7.7 Hz, ArH), 7.71 (t, 1H, J =
7.5 Hz, ArH), 7.64 (t, 1H, J = 7.6 Hz, ArH), 4.42 (q, 2H, J =
7.1 Hz, CH2), 1.42 (t, 3H, J = 7.1 Hz, CH3).
Ethyl (E)-2-cyano-3-(3-trifluoromethylphenyl)-2-propenoate
(Table 4, entry k). White solid, melting point 77–78 ◦C, 1H
NMR (CDCl3): d 8.29 (t, 2H, J = 3.7 Hz, ArH), 8.12 (s, 1H,
CH), 7.81 (d, 1H, J = 7.8 Hz, ArH), 7.67 (t, 1H, J = 7.9 Hz,
ArH), 4.41 (q, 2H, J = 7.1 Hz, CH2), 1.42 (t, 3H, J = 7.1 Hz,
CH3).
2-(4-Methoxyphenylmethylene)malononitrile (Table 5, entry
b). Yellow solid, melting point 110–112 ◦C, 1H NMR (CDCl3):
d 7.91 (d, 2H, J = 8.9 Hz, ArH), 7.66 (s, 1H, CH), 7.02 (d,2H,
J = 9.0 Hz, ArH), 3.92 (s, 3H, CH3).
2-(2-Methoxyphenylmethylene)malononitrile (Table 5, entry f).
Yellow solid, melting point 79–80 ◦C, 1H NMR (CDCl3): d 8.30
(s, 1H, CH), 8.18 (d, 1H, J = 7.9 Hz, ArH), 7.59 (m, 1H, ArH),
7.07 (t, 1H, J = 7.7 Hz, ArH), 6.99 (d, 1H, J = 8.5 Hz, ArH),
3.93 (s, 3H, OCH3).
2-(2-Furylmethylene)malonitrile (Table 5, entry i). Deep yellow
solid, melting point 70–72 ◦C, 1H NMR (CDCl3): d 7.82 (d, 1H,
J = 1.5 Hz), 7.53 (s, 1H, CH), 7.37 (d, 1H, J = 3.7 Hz), 6.73 (dd,
1H, J1 = 1.7 Hz, J2 = 3.7 Hz).
3.3.4 Reusability of the catalyst PANPF-3. In order to
investigate the reusability of the catalyst, 0.500 g PANPF-
3 was used to catalyze the condensation of benzaldehyde
(10 mmol) with ethyl cyanoacetate (10 mmol) in ethanol (20 mL).
After the completion (1.5 h) of the reaction, the fiber was
filtered out and washed with ethanol for three times, and
then the recycled catalyst was directly used for the next cycle.
The yields of the Knoevenagel condensation catalyzed by the
recovered catalyst decrease only by 2% after ten recycles (see Ta-
ble 6). Compared to SBILs 3 catalyst [1-(2¢-diethylamino)ethyl-
3-(3-propyltriethoxysilane)imidazolium hexafluorophosphate
grafted HAP-g-Fe2O3] (4 times)11 and G3PAMAM on PS
catalyst [polystyrene-supported poly(amidoamine) dendrimers]
(5 times),17 PANPF-3 exhibits a much superior reusability
(10 times).
Ethyl (E)-2-cyano-3-(3-methoxyphenyl)-2-propenoate (Ta-
◦
1
ble 4, entry l). Yellow solid, melting point 52–54 C, H NMR
(CDCl3): d 8.21 (s, 1H, CH), 7.59 (s, 1H, ArH), 7.51 (d, 1H, J =
7.7 Hz, ArH), 7.40 (t, 1H, J = 8.0 Hz, ArH), 7.11 (dd, 1H, J1 =
2.5 Hz, J2 = 8.3 Hz, ArH), 4.39 (q, 2H, J = 7.1 Hz, CH2), 3.86
(s, 3H, OCH3), 1.40 (t, 3H, J = 7.1 Hz, CH3).
1834 | Green Chem., 2011, 13, 1828–1836
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