Khodabakhsh Niknam et al. / Chinese Journal of Catalysis 34 (2013) 2245–2254
lization from ethanol (95%). The recovered catalyst was dried
Elemental analysis for C19H20N2O2: C, 74.00; H, 6.54; N, 9.08;
and reused in further reactions.
found: C, 73.73; H, 6.65; N, 8.92.
2‐Amino‐7,7‐dimethyl‐5‐oxo‐4‐phenyl‐5,6,7,8‐tetrahydro‐4
H‐chromene‐3‐carbonitrile (4a). mp 224–226 °C (226–228 °C
[9]). 1H NMR (400 MHz, CDCl3): δ 1.07 (s, 3H), 1.14 (s, 3H), 2.22
(d, 1H, J = 16.4 Hz), 2.28 (d, 1H, J = 16.4 Hz), 2.45–2.53 (m, 2H),
4.43 (s, 1H), 4.54 (s, 2H, NH2), 7.20–7.33 (m, 5H). 13C NMR (100
MHz, CDCl3): δ 27.71, 28.91, 32.22, 35.53, 40.70, 50.68, 114.09,
118.61, 127.18, 127.56, 128.62, 143.15, 157.44, 161.49, 195.83.
2‐Amino‐4‐(4‐bromphenyl)‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetra‐
hydro‐4H‐chromene‐3‐carbonitrile (4b). mp 201–203 °C
2‐Amino‐4‐(4‐isopropyl‐phenyl)‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐
tetrahydro‐4H‐chromene‐3‐carbonitrile (4h). mp 198–200 °C.
1H NMR (400 MHz, CDCl3): δ 0.99 (s, 3H), 1.11–1.15 (s, 9H),
2.26 (d, 1H, J = 16.0 Hz), 2.31 (d, 1H, J = 16.0 Hz), 2.53–2.62 (m,
2H), 2.72–2.80 (m, 1H), 4.23 (s, 1H), 6.98 (s, 2H, NH2), 7.01 (d,
2H, J = 8.0 Hz), 7.24 (d, 2H, J = 8.0 Hz). 13C NMR (100 MHz,
CDCl3): δ 22.77, 23.46, 26.29, 28.31, 31.88, 35.08, 50.17, 58.42,
113.11, 120.12, 126.15, 126.84, 142.97, 146.29, 158.94, 162.41,
195.67. Elemental analysis for C21H24N2O2: C, 74.97; H, 7.19; N,
8.33; found: C, 74.71; H, 7.30; N, 8.07.
1
(201–203 °C [32]). H NMR (400 MHz, CDCl3): δ 1.25 (s, 3H),
1.27 (s, 3H), 2.19–2.29 (m, 2H), 2.47 (s, 2H), 4.40 (s, 1H), 4.63
(s, 2H), 7.14 (d, 2H, J = 8.0 Hz), 7.44 (d, 2H, J = 8.0 Hz). 13C NMR
(100 MHz, CDCl3): δ 27.65, 28.90, 32.23, 35.18, 40.67, 50.61,
118.44, 121.03, 129.41, 131.73, 135.67, 142.86, 195.91.
2‐Amino‐4‐(4‐fluorophenyl)‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetra‐
hydro‐4H‐chromene‐3‐carbonitrile (4c). mp 198–200 °C (210–
211 °C [35]). 1H NMR (400 MHz, CDCl3): δ 1.05 (s, 3H), 1.14 (s,
3H), 2.22 (d, 1H, J = 16.4 Hz), 2.28 (d, 1H, J = 16.4 Hz), 2.47 (s,
2H), 4.42 (s, 1H), 4.58 (s, 2H), 7.00 (t, 2H, J = 8.4 Hz), 7.22–7.29
(m, 2H). 13C NMR (100 MHz, CDCl3): δ 27.65, 28.89, 32.23,
34.93, 40.67, 50.65, 113.96, 115.35, 115.56, 118.50, 129.17,
129.25, 138.97, 157.46, 160.67, 161.48, 195.87.
2‐Amino‐7,7‐dimethyl‐5‐oxo‐4‐(3,4,5‐trimethoxy‐phenyl)‐5,
6,7,8‐tetrahydro‐4H‐chromene‐3‐carbonitrile (4i). mp 171–
173 °C. 1H NMR (400 MHz, CDCl3): δ 1.10 (s, 3H), 1.14 (s, 3H),
2.25–2.32 (m, 2H), 2.44–2.54 (m, 2H), 3.81 (s, 3H), 3.84 (s, 6H),
4.35 (s, 1H), 4.54 (s, 2H), 6.43 (s, 2H). 13C NMR (100 MHz,
CDCl3): δ 27.34, 29.15, 32.12, 35.75, 40.65, 50.62, 56.07, 60.74,
62.81, 104.50, 113.71, 118.90, 136.88, 139.17, 153.19, 157.68,
161.92, 196.11. Elemental analysis for C21H24N2O5: C, 65.61; H,
6.29; N, 7.29; found: C, 65.36; H, 6.39; N, 7.02.
2‐Amino‐4‐(4‐dimethylamino‐phenyl)‐7,7‐dimethyl‐5‐oxo‐
5,6,7,8‐tetrahydro‐4H‐chromene‐3‐carbonitrile (4j). mp 201–
203 °C (202–204 °C [32]). 1H NMR (400 MHz, CDCl3): δ 1.05 (s,
3H), 1.10 (s, 3H), 2.19–2.27 (m, 2H), 2.42–2.48 (m, 2H), 2.91 (s,
6H), 4.33 (s, 1H), 4.44 (s, 2H), 6.64 (d, 2H, J = 8.0 Hz), 7.08 (d,
2H, J = 8.0 Hz). 13C NMR (100 MHz, CDCl3 and DMSO‐d6): δ
27.52, 29.02, 32.12, 34.85, 50.73, 60.37, 112.46, 114.05, 120.16,
128.16, 132.53, 149.43, 158.53, 161.66, 195.88.
2‐Amino‐4‐(2,4‐dichlorophenyl)‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐
tetrahydro‐4H‐chromene‐3‐carbonitrile (4d). mp 114–116 °C
1
(115–117 °C [32]). H NMR (400 MHz, CDCl3): δ 1.07 (s, 3H),
1.13 (s, 3H), 2.19 (d, 1H, J = 16.4 Hz), 2.26 (d, 1H, J = 16.4 Hz),
2.43–2.51 (m, 2H), 4.81 (s, 3H), 7.15–7.22 (m, 2H), 7.36 (d, 1H, J
= 1.6 Hz). 13C NMR (100 MHz, CDCl3): δ 27.69, 28.91, 32.14,
33.56, 40.62, 50.53, 112.28, 118.40, 127.42, 130.00, 131.45,
133.45, 133.98, 138.48, 158.04, 162.61, 195.94.
2.4. General procedure for synthesis of 2‐amino‐4H‐pyrans
2‐Amino‐4‐(4‐cyanophenyl)‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetra‐
hydro‐4H‐chromene‐3‐carbonitrile (4e). mp 208–210 °C (209–
211 °C [37]). 1H NMR (400 MHz, CDCl3): δ 1.03 (s, 3H), 1.13 (s,
3H), 2.19–2.29 (m, 2H), 2.40–2.48 (m, 2H), 4.47 (s, 1H), 4.64 (s,
2H), 7.38–7.48 (m, 2H), 7.58–7.64 (m, 2H). 13C NMR (100 MHz,
CDCl3): δ 27.56, 28.88, 32.16, 36.25, 50.50, 58.25, 110.32,
112.67, 118.81, 119.48, 128.61, 132.26, 149.82, 158.99, 162.79,
195.77.
2‐Amino‐4‐(3‐cyanophenyl)‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetra‐
hydro‐4H‐chromene‐3‐carbonitrile (4f). mp 170–172 °C. 1H
NMR (400 MHz, CDCl3): δ 1.05 (s, 3H), 1.14 (s, 3H), 2.22 (d, 1H, J
= 16.4 Hz), 2.28 (d, 1H, J = 16.4 Hz), 2.45–2.55 (m, 2H), 4.47 (s,
1H), 4.75 (s, 2H) 7.41–7.45 (m, 1H), 7.52–7.59 (m, 3H). 13C NMR
(100 MHz, CDCl3): δ 27.79, 28.75, 32.28, 35.49, 40.65, 50.56,
112.71, 113.16, 118.21, 118.88, 129.40, 130.93, 131.23, 144.76,
157.82, 162.12, 195.81. Elemental analysis for C19H17N3O2: C,
71.46; H, 5.37; N, 13.16; found: C, 71.20; H, 5.47; N, 12.96.
2‐Amino‐7,7‐dimethyl‐5‐oxo‐4‐m‐tolyl‐5,6,7,8‐tetrahydro‐4
H‐chromene‐3‐carbonitrile (4g). mp 198–200 °C. 1H NMR (400
MHz, CDCl3): δ 0.97 (s, 3H), 1.13 (s, 3H), 2.16 (s, 3H), 2.25 (d,
1H, J = 16.0 Hz), 2.32 (d, 1H, J = 16.0 Hz), 2.58 (s, 2H), 4.31 (s,
1H), 6.76 (s, 2H, NH2), 7.17 (d, 1H, J = 7.6 Hz), 7.34 (s, 1H), 7.39
(d, 1H, J = 7.2 Hz ), 7.73–7.80 (m, 1H). 13C NMR (100 MHz,
CDCl3): δ 20.29, 27.29, 28.91, 32.28, 36.08, 50.47, 58.82, 113.25,
120.22, 126.75, 128.82, 132.97, 145.29, 158.94, 162.91, 196.17.
To a mixture of aromatic aldehyde (1 mmol), malonitrile (1
mmol), and ethyl acetoacetate (1 mmol) in 3 mL of aqueous
ethanol (1:1), catalyst SBPPSP (0.05 g, 4.3 mol%) was added,
and the mixture was refluxed for an appropriate time. After
completion of the reaction, as indicated by TLC, ethanol (10
mL) was added, and the reaction mixture was filtered. The res‐
idue was washed with warm ethanol (3 × 5 mL) to separate the
heterogeneous catalyst. After cooling, the crude product was
precipitated and then purified by recrystallization from ethanol
(95%). The recovered catalyst was dried and reused in subse‐
quent reactions.
6‐Amino‐4‐(4‐chloro‐phenyl)‐5‐cyano‐2‐methyl‐4H‐pyran‐
3‐carboxylic acid ethyl ester (5a). mp 170–172 °C (172–174 °C
[43]). 1H NMR (400 MHz, CDCl3): δ 1.11 (t, 3H, J = 7.2 Hz), 2.42
(s, 3H), 4.02–4.1 (m, 2H), 4.52 (S, 1H), 4.71 (S, 2H), 7.35 (d, 2H, J
= 8.4 Hz ), 7.63 (d, 2H, J = 8.4 Hz). 13C NMR (100 MHz, CDCl3): δ
13.95, 18.51, 38.30, 60.82, 61.69, 107.57, 118.81, 128.76,
128.95, 132.95, 142.43, 157.12, 157.59, 165.70.
6‐Amino‐4‐(3‐chloro‐phenyl)‐5‐cyano‐2‐methyl‐4H‐pyran‐
3‐carboxylic acid ethyl ester (5b). mp 155–156 °C (153–156 °C
[43]). 1H NMR (400 MHz, CDCl3): δ 1.14 (t, 3H, J = 7.2 Hz), 2.40
(s, 3H), 4.03–4.12 (m, 2H), 4.45 (s, 1H), 4.59 (s, 2H), 7.16 (d, 2H,
J = 8.4 Hz), 7.29 (d, 2H, J = 8.4 Hz). 13C NMR (100 MHz, CDCl3): δ
14.24, 18.58, 39.77, 57.63, 60.64, 107.88, 114.31, 114.45,
118.30, 120.28, 129.80, 146.70, 156.75, 157.87, 159.06, 165.96.