“…Chromatography (petroleum ether/EtOAc 10:1–8:1), white solid, 41.6 mg, yield 77%, mp > 300 °C (lit. : mp 290–292 °C). 1 H NMR (400 MHz, DMSO- d 6 ) δ 13.01 (s, 1H), 8.30 (d, J = 8.0 Hz, 2H), 7.89 (d, J = 8.0 Hz, 2H), 7.79 (d, J = 7.2 Hz, 2H), 7.74–7.36 (m, 5H), 7.24 (s, 2H).…”