“…Recrystallization from AR-grade acetone afforded 12d as a white powder: Mp 236–238 °C; Lit Mp 79 231–232 °C; 1 H NMR (300 MHz, DMSO-d 6 ) δ ppm 11.02 (s, 1H), 9.17 (d, J = 2.0 Hz, 2H), 9.02 (t, J = 2.0 Hz, 1H), 8.94 (d, J = 2.4 Hz, 1H), 8.38 (m, 1H), 8.20 (m 1H), 7.45 (m, 1H); 13 C NMR (101 MHz, DMSO-d 6 ) δ ppm 162.3, 148.7, 145.9, 142.8, 137.4, 135.5, 128.6, 128.4, 124.2, 121.8; HRMS-ES − : Observed 287.0403 (M-H) − ; Calculated 287.0416 for C 12 H 7 N 4 O 5 ; HPLC: 99.3%.…”