F. El hajri, Z. Benzekri, S. Sibous et al.
Journal of Molecular Structure 1230 (2021) 129890
recorded on a 300 MHz and 75 MHz Brucker spectrometer in
DMSO-d6.
2.5.4. 2-(phenylmethylene) malononitrile (3d)
Colorless solid, yield: 80%, mp 80–81 °C (lit. [22] 80–81 °C); 1
H
NMR (300 MHz, DMSO-d ) δ: 7.57–7.70 (m, 3H, ArH), 7.59 (d, 2H,
6
2
.2. General procedure for the preparation of catalyst
J = 7.2 Hz, ArH), 8.50 (s, 1H, C=CH). 13C NMR (75 MHz, DMSO-d6)
δ: 155.7, 134.8, 131.7, 131.6, 130.9, 129.9, 114.6, 113.5, 82.0.
Hydrazinium (1+) hexafluorosilicate (N H ) SiF crystal has
2
5
2
6
been recently synthesized by slow evaporation at room tempera-
ture of aqueous solution containing stoichiometric (2:1) amounts
2
.5.5. Methyl-2-cyano-3-phenylacrylate (3e)
White solid, yield: 67%, mp 84–85 °C (lit. [22] 84–85 °C); 1
H
of hydrazine NH NH and H SiF6 acid [43]. The synthesis method
2
2
2
NMR (300 MHz, DMSO-d ) δ: 3.84 (t, 3H, CH ), 7.54–7.65 (m, 3H,
6
3
consists to add the H SiF acid (Percentage = 34 % in weight) to
2
6
ArH), 8.03 (d, 2H, J = 8.4 Hz, ArH), 8.38 (s, 1H, C=CH). 13C NMR
the pure NH NH2 (Percentage = 100 %) dissolved in the minimal
2
(
75 MHz, DMSO-d ) δ: 162.8, 155.6, 133.9, 131.7, 131.6, 129.8, 115.0,
6
distilled water. The obtained solution was taken under ambient
temperature for evaporation; after few weeks, colorless single crys-
tals suitable to X-ray structure determination were obtained [43].
The reaction equation mechanisms adopted for this synthesis may
be described as the following:
102.8, 53.8.
2.5.6. 2-(p-tolylmethylene) malononitrile (3f)
White solid, yield: 82%, mp 118–119 °C (lit. [22] 118–119 °C); 1
H
−
+
Firstly: NH NH
2
+ H O → [OH
+, NH NH2 (aq)]
NMR (300 MHz, DMSO-d6) δ: 2.37 (s, 3H), 7.38 (d, J = 8.4 Hz, 2H),
2 (aq)
−
2
(aq)
3
+
13
Secondly: 2 [OH
NH NH
] + H SiF → (N H ) SiF + 2H O7.82 (d, J = 8.4 Hz, 2H), 8.39 (s, 1H, C=CH). C NMR (75 MHz,
(
aq),
3
2 (aq)
2
6
2
5
2
6
2
DMSO-d ) δ: 161.6, 146.1, 131.1, 130.5, 129.1, 114.8, 113.8, 80.3, 21.5.
6
2
.3. General operating mode of Knoevenagel condensation
2
.5.7. Ethyl-2-cyano-3-p-tolylacrylate (3g)
White solid, yield: 54%, mp 91–92 °C (lit. [22] 91–92 °C); 1
A mixture of aromatic aldehyde 1 (1 mmol), the active methy-
lene compound 2 (malononitrile, ethyl cyanoacetate or methyl
cyanoacetate) (1 mmol) and (N H ) SiF (0.1 mol %) were stirred
H
NMR (300 MHz, DMSO-d ) δ: 1.31 (t, J = 7.2 Hz, 3H), 2.37 (s, 3H),
6
2
5
2
6
4
.34 (q, J = 7.4 Hz, 2H), 7.79 (d, J = 7.7 Hz, 2H), 7.90 (d, J = 7.2 Hz,
in 2 ml of ethanol at room temperature. The Progress of the reac-
tion was monitored by TLC using n-hexane / EtOAc (5:1) as an elu-
ent. After completion of reaction, the dichloromethane was added
to the reaction mixture, the catalyst was recovered by simple fil-
tration and the filtrate was cooled. The obtained solid was filtered
and recrystallized in hot ethanol.
13
2
H), 8.05 (s, 1H). C NMR (75 MHz, DMSO-d ) δ: 163.0, 155.5,
6
144.9, 131.4, 130.4, 129.1, 116.2, 101.2, 63.1, 14.3, 21.3.
2
.5.8. 2-(4-nitrophenylmethylene) malononitrile (3h)
Yellow solid, yield: 98%, mp 161–162 °C (lit. [22] 160–161 °C);
1
H NMR (300 MHz, DMSO-d ) δ: 8.11 (d, J = 8.7 Hz, 2H), 8.29 (d,
6
13
2
.4. General operating mode of synthesis of biscoumarin derivatives
J = 8.7 Hz, 2H), 8.67 (s, 1H, C=CH). C NMR (75 MHz, DMSO-d )
6
δ: 159.7, 150.1, 137.1, 131.9, 124.8, 114.0, 112.9, 82.4.
A
mixture of aromatic aldehyde
hydroxycoumarine 4 (2 mmol) in a 50 ml round-bottomed flask,
N H ) SiF (0.2 mol %) was added to 2 ml of ethanol. The reac-
1
(1 mmol) and 4-
2
.5.9. Methyl-2-cyano-3-(4-nitrophenyl) acrylate (3i)
(
2
5
2
6
Yellow solid, yield: 87%, mp 172–173 °C (lit. [22] 172–173 °C);
tion mixture was heated at reflux for appropriate time (Table 9).
After completion of the reaction as monitored by TLC. The crude
1
H NMR (300 MHz, DMSO-d ) δ: 3.88 (s, 3H, CH ), 8.19 (d, 2H,
6
3
J = 7.1 Hz, ArH), 8.34 (d, 2H, J = 7.1 Hz, ArH), 8.48 (s, 1H, C=CH).
reaction mixture was dissolved in CH Cl and the catalyst was sep-
13
2
2
C NMR (75 MHz, DMSO-d ) δ: 162.1, 153.1, 149.8, 137.6, 132.1,
6
arated out by a simple filtration. The obtained solid was filtered
and recrystallized from hot ethanol.
1
31.0, 124.4, 115.1, 107.0, 53.9.
All the synthesized products 3a-1 [22] and 5a-f [30,44] are ac-
knowledged and were absolutely characterized by 1H and 13C NMR
2.5.10. Ethyl-2-cyano-3-(4-nitrophenyl) acrylate (3j)
Yellow solid, yield: 83%, mp 168–169 °C (lit. [22] 168–169 °C);
and confirmed by comparison of their melting points and their
spectral data with those reported in the literature.
1
H NMR (300 MHz, DMSO-d ) δ: 1.28 (t, 3H, J = 7.2 Hz, CH ), 4.29
6
3
(
q, 2H, J = 7.2 Hz, CH ), 7.62 (d, 2H, J = 8.4 Hz, ArH), 8.02 (d, 2H,
2
13
2
.5. Spectroscopic characterization data for the selected products
J = 8.4 Hz, ArH), 8.30 (s, 1H, C=CH). C NMR (75 MHz, DMSO-d6)
δ: 162.0, 154.0, 138.4, 132.8, 130.6, 129.9, 115.8, 103.6, 62.9, 14.4.
2
.5.1. 2-(4-chlorophenylmethylene) malononitrile (3a)
Colorless solid, yield: 96%, mp 160–162 °C (lit. [22] 159–160 °C);
ꢀ
2
.6. 3,3 -(phenylmethylene)bis(4-hydroxy-2H-chromen-2-one) (5a)
1
H NMR (300 MHz, DMSO-d ) δ: 7.67 (d, 2H, J = 8.7 Hz), 7.92 (d,
6
13
2
H, J = 8.7 Hz), 8.49 (s, 1H, C=CH). C NMR (75 MHz, DMSO-d )
6
White solid. yield: 95%, mp 233–234 °C (lit. [30] 228–230 °C);
δ: 160.5, 139.5, 132.5, 131.6, 130.1, 114.4, 113.4, 82.7.
1
H NMR (300 MHz, DMSO-d ) δppm: 7.93 (1H, s, OH), 7.91−7.16
6
(
(
13H, m, aromatic H), 6.38 (1H, s, CH), 5.63 (1H, br s, OH). 13C NMR
2
.5.2. Methyl-3-(4-chlorophenyl)-2-cyanoacrylate (3b)
75 MHz, DMSO-d ) δppm: 35.95, 104.06, 115.91, 117.99, 123.68,
23.89, 125.51, 126.67, 128.02, 131.83, 140, 152.20, 164.8, 165.39.
6
White solid, yield: 84%, mp 120–121 °C (lit. [22] 120–121 °C);
1
1
H NMR (300 MHz, DMSO-d ) δ: 3.84 (t, 3H, OCH ), 7.65 (d, 2H,
6
3
J = 8.4 Hz, ArH), 8.04 (d, 2H, J = 8.4 Hz, ArH), 8.38 (s, 1H, C=CH).
ꢀ
one) (5b)
13
2.7. 3,3 -(4-Chlorophenylmethylene)bis-(4-hydroxy-2H-chromen-2-
C NMR (75 MHz, DMSO-d ) δ: 162.5, 154.2, 138.5, 132.5, 130.6,
6
129.9, 115.8, 103.4, 53.8.
2
.5.3. Ethyl-3-(4-chlorophenyl)-2-cyanoacrylate (3c)
Colorless solid, yield: 73%, mp 89–90 °C (lit. [22] 89–90 °C); 1
White solid. yield: 92%, mp 258–260 °C (lit. [30] 254–256 °C);
1
H
H NMR (300 MHz, DMSO-d ) δppm: 7.86 (1H, s, OH), 7.83−7.11
6
NMR (300 MHz, DMSO-d ) δ: 1.28 (t, 3H, J = 7.2 Hz, CH ), 4.29
(12H, m, aromatic H), 6.27 (1H, s, CH), 5.61 (1H, br s, OH). 13C NMR
6
3
(
q, 2H, J = 7.2 Hz, CH ), 7.61 (d, 2H, J = 8.7 Hz, ArH), 8.00 (d, 2H,
(75 MHz, DMSO-d ) δppm: 35.72, 103.34, 115.61, 119.20, 123.15,
2
6
13
J = 8.7 Hz, ArH), 8.33 (s, 1H, C=CH). C NMR (75 MHz, DMSO-d )
124.03, 127.68, 128.58, 129.56, 131.28, 140.77, 152.41, 164.46,
166.96.
6
δ: 162.0, 154.0, 138.5, 132.8, 130.5, 129.8, 115.7, 103.5, 62.9, 14.3.
2