One-pot catalyst-free synthesis of 3-heterocyclic coumarins
(1H, dd, J = 9.04, 2.34 Hz, 6-H), 6.59 (1H, s, 8-H), 3.49 (4H, q, J = 7.07 Hz,
N(CH2CH3)2), 1.16 (6H, t, J = 7.02 Hz, N(CH2CH3)2); ESI–MS: 436.1
[M ? Na]?. HR-ESI–MS for C20H19N3NaO5S: Found 436.0942, Calcd.
436.0943.
3-(20-Benzoxazole)-6-chloro-2H-1-benzopyran-2-one (4n): yellow solid. M.p.
237–239 °C. 1H NMR (500 MHz, DMSO) d: 8.70 (1H, s, 4-H), 7.88 (1H, d,
J = 6.50 Hz, 5-H), 7.65–7.63 (2H, m, 50-H, 60-H), 7.61 (1H, dd, J = 8.76, 2.35 Hz,
7-H), 7.45–7.37 (3H, m, 8-H, 40-H, 70-H). ESI–MS: 320 [M ? Na]?. HR-ESI–MS
for C16H8ClNNaO3: Found 320.0086, Calcd. 320.009.
3-(50-Methyl-20-benzoxazole)-6-chloro-2H-1-benzopyran-2-one (4o): yellow sol-
1
id. M.p. 225–227 °C. H NMR (500 MHz, DMSO) d: 8.67 (1H, s, 4-H), 7.63 (2H,
bs, 5-H,70-H), 7.59 (1H, dd, J = 8.76, 2.36 Hz, 7-H), 7.50 (1H, d, J = 8.29 Hz,
8-H), 7.36 (1H, d, J = 8.77 Hz, 40-H), 7.22 (1H, d, J = 8.23 Hz, 60-H), 2.50 (3H, s,
Ar-CH3). 13C NMR (DMSO) d: 158.0, 155.4, 152.6, 148.3, 144.6, 141.2, 134.6,
133.3, 128.7, 128.6, 127.3, 119.8, 119.7, 118.2, 115.4, 110.4, 21.0; ESI–MS: 334
[M ? Na]?. HR-ESI–MS for C17H10ClNNaO3: Found 334.0273, Calcd. 334.0247.
3-(20-Benzoxazole)-6-bromo-2H-1-benzopyran-2-one (4p): yellow solid. M.p.
229–231 °C. 1H NMR (500 MHz, CDCl3) d: 8.70 (1H, s, 4-H), 7.88 (1H, d,
J = 7.29 Hz, 5-H), 7.81 (1H, d, J = 2.28 Hz, 60-H), 7.74 (1H, dd, J = 8.79,
2.29 Hz, 50-H), 7.64 (1H, d, J = 7.38 Hz, 7-H), 7.45–7.39 (2H, m, 40-H, 70-H), 7.32
(1H, d, J = 8.77 Hz, 8-H). ESI–MS: 364, 366 [M ? Na]?. HR-ESI–MS for
C16H8BrNNaO3: Found 363.9608; 365.9588, Calcd. 363.9585; 365.9585.
3-(50-Methyl-20-benzoxazole)-6-bromo-2H-1-benzopyran-2-one (4q): yellow sol-
id. M.p. 248–251 °C. 1H NMR (500 MHz, CDCl3) d: 8.67 (1H, s, 4-H), 7.78 (1H, d,
J = 2.27 Hz, 5-H), 7.72 (1H, dd, J = 8.79, 2.29 Hz, 7-H), 7.64 (1H, s, 70-H), 7.50
(1H, d, J = 8.34 Hz, 40-H), 7.30 (1H, d, J = 8.81 Hz, 8-H), 7.22 (1H, d,
J = 8.45 Hz, 60-H), 2.50 (3H, s, Ar-CH3). ESI–MS: 356.3, 358.3 [M ? 2H]?.
HR-ESI–MS for C17H10BrNNaO3: Found 377.9762; 379.9744, Calcd. 377.9742;
379.9742.
3-(50-Chloro-20-benzoxazole)-6-bromo-2H-1-benzopyran-2-one (4r): Yellow sol-
id. M.p. 274–276 °C. 1H NMR (500 MHz, CDCl3) d: 8.70 (1H, s, 4-H), 7.84 (1H, d,
J = 2.00 Hz, 5-H), 7.82 (1H, d, J = 2.23 Hz, 40-H), 7.76 (1H, dd, J = 8.76,
2.24 Hz, 70-H), 7.57 (1H, d, J = 8.68 Hz, 7-H), 7.41 (1H, dd, J = 8.68, 1.93 Hz, 60-
H), 7.32 (1H, d, J = 8.79 Hz, 8-H). ESI–MS: 376.3, 378.3 [M ? 2H]?. HR-ESI–
MS for C16H7BrClNNaO3: Found 397.9215; 399.9195, Calcd. 397.9196; 399.9196.
3-(50-Sulfonylamine-20-benzoxazole)-6-bromo-2H-1-benzopyran-2-one (4s): yel-
low solid. M.p. [ 300 °C. 1H NMR (500 MHz, DMSO) d: 9.09 (1H, s, 40-H), 8.28-
8.26 (2H, m, 60-H, 5-H), 8.05 (1H, d, J = 8.63 Hz, 4-H), 7.97 (1H, d, J = 8.59 Hz,
7-H), 7.91 (1H, d, J = 8.52 Hz, 70-H), 7.53–7.48 (1H, m, 8-H). 13C NMR(DMSO)
d: 160.6, 155.3, 153.2, 151.6, 145.7, 141.4, 140.9, 136.6, 131.9, 124.1, 120.1, 118.5,
117.8, 116.5, 114.9, 111.7; ESI–MS: 420.9, 422.9 [M ? H]?. HR-ESI–MS for
C16H10BrN2O5S: Found 420.9486; 422.9486, Calcd. 420.9494; 422.9494.
3-(20-Benzimidazole)-2H-1-benzopyran-2-one (6a): yellow solid. M.p. 257–259 °C;
1H NMR (500 MHz, CDCl3) d: 11.32 (bs, 1H, NH), 9.13 (1H, s, 4-H), 7.82 (1H, s,
5-H), 7.72 (1H, d, J = 7.75 Hz, 7-H), 7.64 (1H, t, J = 7.16 Hz, 40-H), 7.56 (1H, s, 70-
H), 7.46 (1H, d, J = 8.33 Hz, 8-H), 7.41 (1H, t, J = 8.41 Hz, 6-H), 7.35–7.31 (2H, m,
123