Further Studies on 3: 4-Benzxanthenes

Intermolecular C–O addition of carboxylic acids to arynes: synthesis of o-hydroxyaryl ketones, xanthones, 4-chromanones, and flavones

“…The residue was purified by flash chromatography on silica gel using hexanes/EtOAc as the eluent to afford the desired xanthone 25 as a white solid in a 55% yield: mp 149–151 °C (lit. mp 48 147–149 °C); 1 H NMR (600 MHz, CDCl 3 ) δ 7.43 (s, 1H), 7.61–7.80 (m, 5H), 7.90–7.94 (m, 1H), 8.27 (d, J = 8.2 Hz, 1H), 8.40 (d, J = 6.4 Hz, 1H), 8.66 (d, J = 6.5 Hz, 1H); 13 C NMR (150 MHz, CDCl 3 ) δ 117.6, 118.1, 121.5, 122.5, 122.9, 124.0, 124.1, 124.4, 126.6, 126.9, 128.1, 129.6, 134.4, 136.6, 153.7, 155.8, 176.9; HRMS (APCI) calcd for [M+H] + C 17 H 11 O 2 247.0754, found 247.0751. The 1 H and 13 C NMR spectral data are in good agreement with the literature data.…”