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(br s, 3H). 13C NMR (75 MHz, DMSO-d6) δ 168.5, 160.9, 159.9, 157.7,
154.5, 153.7, 148.1, 145.8, 130.9, 129.6 (2C), 128.4 (2C), 111.9, 111.5,
102.4, 98.9, 77.2, 51.1, 33.9, 24.4; HRESIMS m/z 414.0750
([C21H16NO635Cl+H]+ calcd. for m/z 414.0744) and m/z 416.0750
([C21H16NO637Cl+H]+ calcd. for m/z 416.0710).
(2E,4E)-Methyl 2-cyano-5-phenylpenta-2,4-dienoate (15)
Yellow bright solid (0.1913 g, yield 89.2%); m.p. 183°C; reaction time
2 h; purity 86%. 1H NMR (300 MHz, DMSO-d6) data: δ 8.05 (m, 1H),
7.61 (m, 2H), 7.42–7.44 (m, 3H), 7.31 (m, 1H), 7.29 (m, 1H), 3.91 (s, 3H).
13C NMR (75 MHz, DMSO-d6) δ 162.8, 155.7, 149.1, 134.6, 131.2,
129.1 (2C), 128.5 (2C), 123.0, 114.5, 104.0, 53.1; HRESIMS m/z
214.0850 ([C13H11NO2+H]+ calcd. for m/z 214.0868).
Methyl 8-amino-10-(4-bromophenyl)-5-hydroxy-4-methyl-2-
oxo-2,10-dihydropyrano[2,3-f]chromene-9-carboxylate (11)
White solid (0.3307 g, yield 73%); m.p. 201.3°C; reaction time 100 min;
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4.1.4 Preparation of 4-aryl-4H-chromenes (16–22)
purity 95.6%. 1H NMR (300 MHz, DMSO-d6)
δ 7.61 (s, 2H,
exchangeable), 7.39 (d, J = 8.4 Hz, 2H), 7.13 (d, J = 8.4 Hz, 2H),
6.51 (s, 1H), 6.08 (d, J = 0.8 Hz, 1H), 4.97 (s, 1H), 3.57 (s, 3H), 2.65
(br s, 3H). 13C NMR (75 MHz, DMSO-d6) δ168.5, 160.9, 159.9, 157.7,
154.5, 153.7, 148.1, 146.2, 131.3 (2C), 130.1 (2C), 119.4, 111.9, 111.5,
102.4, 98.9, 77.1, 51.1, 34.0, 24.4; HRESIMS m/z 458.0271
([C21H16NO679Br+H]+ calcd. for m/z 458.0239) and m/z 460.0252
([C21H16NO681Br+H]+ calcd. for m/z 460.0214).
Phloroglucinol (purchased from Sigma–Aldrich) (0.126 g, 1 mmol) was
mixed with a methanol solution (1 mL) of 1.0 equivalent of different
benzaldehyde derivatives. Methyl α-cyanoacetate (1.0 equivalent)
(purchased from Sigma–Aldrich) and an aqueous solution (19 mL) of
K2CO3 (0.09 g, 0.65 mmol) (purchased from Spectrum®) were added to
the mixture. The medium was stirred at room temperature and the
reaction was complete within 18 h based on the TLC profile. The
precipitate observed in the medium was purified by filtration and
washed during this separation process with mixture water/MeOH (1:1).
Methyl 8-amino-5-hydroxy-4-methyl-10-(4-nitrophenyl)-2-oxo-
2,10-dihydropyrano[2,3-f]chromene-9-carboxylate (12)
Pale white solid (0.3180 g, yield 75%); m.p. 209.6°C; reaction time
100 min; purity 89.3%; 1H NMR (300 MHz, DMSO-d6) δ 8.11 (d,
J = 8.6 Hz, 2H), 7.45 (d, J = 8.6 Hz, 2H), 6.52 (s, 1H), 6.11 (br s, 1H),
5.12 (s, 1H), 3.59 (s, 3H), 2.69 (br s, 3H). 13C NMR (75 MHz, DMSO-
d6) δ 168.3, 160.8, 159.8, 157.8, 154.8, 154.4, 153.7, 148.1, 146.2,
129.2 (2C), 123.8 (2C), 111.9, 110.5, 102.4, 98.9, 76.4, 51.1, 34.8,
24.4; HRESIMS m/z 425.0966 ([C21H16N2O8+H]+ calcd. for m/z
425.0985).
Methyl 2-amino-4-(4-chlorophenyl)-5,7-dihydroxy-4H-
chromene-3-carboxylate (16)
Yellow solid (0.1804 g, yield 51.4%); m.p. 195.7°C; purity 58.2%;
1H NMR (300 MHz, CDCl3) δ 9.64 (s, 1H, exchangeable), 9.43 (s, 1H,
exchangeable), 7.55 (s, 2H, exchangeable), 7.23 (d, J = 8.3 Hz, 2H), 7.12
(d, J = 8.3 Hz, 2H), 6.04 (br s, 1H), 5.96 (br s, 1H), 4.83 (s, 1H), 3.52 (s,
3H). 13C NMR (75 MHz, CDCl3) δ 168.9, 161.9, 157.5, 155.4, 150.8,
147.2, 130.3, 129.5 (2C), 128.1 (2C), 105.3, 99.0, 94.0, 77.5, 50.8,
33.8; HRESIMS m/z 348.0642 (C17H14NO535Cl+H]+ calcd. for m/z
348.0639) and m/z 350.0642 (C17H14NO537Cl+H]+ calcd. for m/z
350.0604).
Methyl 8-amino-10-(3,4-dimethoxyphenyl)-5-hydroxy-4-
methyl-2-oxo-2,10-dihydropyrano[2,3-f]chromene-9-
carboxylate (13)
White solid (0.3073 g, yield 70%); m.p. 223.5°C; reaction time
120 min; purity 86.1%. 1H NMR (300 MHz, DMSO-d6) δ 7.50 (s, 2H,
exchangeable), 7.02 (d, J = 1.7 Hz, 1H), 6.76 (d, J = 8.4 Hz, 1H), 6.63 (dd,
J = 8.4, 1.7 Hz, 1H), 6.21 (s, 1H), 5.75 (br s, 1H), 5.06 (s, 1H), 3.65 (s, 3H),
3.64 (s, 3H), 3.58 (s, 3H), 2.59 (s, 3H). 13C NMR (75 MHz, DMSO-d6) δ
169.1, 161.8, 160.7, 155.4, 153.4, 153.9, 148.4, 148.3, 147.3, 140.3,
119.0, 113.9, 112.2, 112.0, 107.7, 99.3, 98.7, 78.2, 55.9, 55.7, 50.9,
33.3, 24.4; HRESIMS m/z 440.1331 ([C23H21NO8+H]+ calcd. for m/z
440.1345).
Methyl 2-amino-4-(4-bromophenyl)-5,7-dihydroxy-4H-
chromene-3-carboxylate (17)
Yellow solid (0.1994 g, yield 51%); m.p. 220.9°C; purity 69.6%;
1H NMR (300 MHz, DMSO-d6) δ 9.65 (s, 1H, exchangeable), 9.44 (s,
1H, exchangeable), 7.55 (s, 2H, exchangeable), 7.37 (d, J = 8.2 Hz, 2H),
7.08 (d, J = 8.2 Hz, 2H), 6.05 (d, J = 1.6 Hz, 1H), 5.97 (d, J = 1.6 Hz, 1H),
4.83 (s, 1H), 3.52 (s, 3H). 13C NMR (75 MHz, DMSO-d6) δ 168.9, 161.8,
157.6, 155.5, 150.8, 147.6, 131.0 (2C), 130.0 (2C), 118.8, 105.2, 99.0,
94.0, 77.4, 50.8, 33.9; HRESIMS m/z 392.0124 ([C17H14NO579Br+H]+
calcd. m/z 392.0134) and m/z 394.0113 ([C17H14NO581Br+H]+ calcd.
m/z 394.0108).
Methyl 8-amino-5-hydroxy-4-methyl-2-oxo-10-(3,4,5-
trimethoxyphenyl)-2,10-dihydropyrano[2,3-f]chromene-9-
carboxylate (14)
Methyl 2-amino-5,7-dihydroxy-4-(4-nitrophenyl)-4H-
Yellowish solid (0.2720 g, yield 58%); m.p. 223.5°C; reaction time
120 min; purity 85.9%; 1H NMR (300 MHz, DMSO-d6) δ 7.61 (s, 2H,
exchangeable), 6.57 (s, 1H), 6.50 (s, 2H), 6.08 (s, 1H), 5.06 (s, 1H), 3.70
(s, 6H), 3.65 (s, 3H), 3.61 (s, 3H), 2.68 (s, 3H). 13C NMR (75 MHz,
DMSO-d6) data: δ 168.7, 161.4, 160.0, 157.9, 154.4, 153.7, 152.9,
148.4, 142.4, 136.4, 112.1, 111.8, 104.9, 102.4, 77.5, 60.3, 56.2, 51.1,
34.2, 24.4; HRESIMS m/z 470.1472 ([C24H23NO9+H]+ calcd. for m/z
470.1451).
chromene-3-carboxylate (18)
Yellow solid (0.1969 g, yield 55%); m.p. 211.4°C; purity 56.6%; 1H NMR
(300 MHz, DMSO-d6) δ 9.65 (br s, 2H exchangeable), 8.08 (d, J = 8.6 Hz,
2H), 7.64 (br s, 2H, exchangeable), 7.37 (d, J = 8.6 Hz, 2H), 6.04 (d,
J = 2.0 Hz, 1H), 5.99 (d, J = 2.0 Hz, 1H), 4.95 (s, 1H), 3.52 (s, 3H).
13C NMR (75 MHz, DMSO-d6) δ 168.8, 161.8, 158.0, 156.0, 155.7,
150.8, 145.9, 129.1 (2C), 123.7 (2C), 104.3, 99.1, 94.2, 76.8, 50.9, 34.8;
HRESIMS m/z 359.0893 ([C17H14N2O7+H]+ calcd. for m/z 359.0879).