A mixture of 2-(3-fluorophenyl)-1-phenylethanone (commercially available) (200 mg, 0.93 mmol), 3-ethoxy-4-hydroxy-5-nitrobenzaldehyde (197 mg, 0.93 mmol), urea (168 mg, 2.8 mmol), conc. hydrochloric acid (0.5 mL) in ethanol (3 mL) was refluxed for 61 hours. After cooling to room temperature, the mixture was evaporated and purified by silica gel column chromatography (petroleum ether/ethyl acetate=3:1) to give Compound 115 (85.8 mg, yield 20%). HNMR (DMSO-d6 400 MHZ): δ 10.31 (brs, 1H), 8.82 (s, 1H), 7.59 (s, 1H), 7.45 (d, J=1.2 Hz, 1H), 7.31-7.22 (m, 6H), 7.10-7.00 (m, 1H), 6.84-6.80 (m, 1H), 6.64-6.56 (m, 2H), 5.26 (d, J=2.4 Hz, 1H), 4.15-4.00 (m, 2H), 1.36 (t, J=6.8 Hz, 3H). MS (ESI): m/z 450.0 [M+H]+.
