HETEROCYCLES, Vol. 81, No. 2, 2010
379
Ethyl 3-Anilino-2H-chromene-4-carboxylate (23)
A mixture of aniline (280 mg, 3.00 mmol), hydroxychromene 18b (600mg, 2.72 mmol), CaSO4 (1.5g),
EtOH (10 mL) and acetic acid (200 mg) was heated at reflux for 4 h with continuous stirring. The mixture
was then filtered, the filter cake washed with EtOH, and the ethanolic solution concentrated. CH2Cl2 (30
mL) was added and the mixture was washed with saturated aqueous NaHCO3 (2 x 10mL) then
concentrated in vacuo to give 23, which crystallized as yellow needles (467 mg, 58%): mp 80 - 82 °C
(EtOH); IR νmax/cm-1 2985, 1644, 1519, 1232; δH: 1.41 (3H, t, J = 7 Hz, -CH3), 4.36 (2H, q, J = 7 Hz, -
CH2-), 4.65 (2H, s, -CH2O-), 6.95 (4H, m, 3'-, 5'-, 4'-, 8-H), 7.18 (2H, m, 2'-, 6'-H), 7.37 (2H, m, 6-, 8-H),
7.89 (1H, dd, J = 5, 3 Hz, 5-H), 11.05 (1H, s, NH); δC: 14.4, 60.1, 64.0, 92.6, 115.8, 122.2, 123.1, 124.2,
124.9, 125.6, 126.4, 129.4, 137.9, 151.9, 153.7, 168.8. Anal. Calcd for C18H17NO3: C, 73.20; H, 5.80; N,
4.74%. Found: C, 73.38; H, 5.91; N, 4.72%.
6H-Chromeno[3,4-b]quinolin-12H-one (24)
Ph2O (3 mL) was preheated under an atmosphere of nitrogen at 120 °C. Ester 23 (200 mg, 0.677 mmol)
was then added as a solution in Ph2O (1 mL) and the temperature of the mixture rapidly increased to 260
ºC and maintained for 15-20 min with continuous stirring. Upon cooling, an off-white slurry was formed.
Hexanes (5 mL) were added and the mixture was filtered. The residue was then boiled in acetone to give
the desired compound 24 as a white amorphous solid (112 mg, 65%): mp >300 ºC (decomp.); IR
νmax/cm-1 2919, 1640, 1559, 1510; δH (DMSO): 5.12 (2H, s, -CH2-), 6.94 (1H, d, J = 8 Hz, 4-H), 7.03 (1H,
t, J = 8 Hz, 2-H), 7.14 (1H, td, J = 8, 2 Hz, 3-H), 7.37 (1H, t, J = 8 Hz, 10-H), 7.54 (1H, d, J = 8 Hz, 8-H),
7.67 (1H, t, J = 7 Hz, 9-H), 8.22 (1H, d, J = 8 Hz, 11-H), 8.93 (1H, dd, J = 8, 2 Hz, 1-H), 12.2 (1H, broad,
NH); δC: 64.7, 108.0, 116.2, 118.7, 122.1, 122.3, 124.1, 126.0, 126.3, 126.7, 127.5, 132.2, 138.6, 144.4,
152.1, 174.0. Anal. Calcd for C16H11NO2: C, 77.10; H, 4.45; N, 5.62%. Found: C, 77.45; H, 4.34; N,
5.34%.
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