3-Fluoroisatoic anhydride

3-Fluoroisatoic anhydride is prepared from 7-fluoroindole (9i) by stirring in a 4:1 mixture of CH3CN/H2O for 1 h at 40℃.
¹ H NMR (DMSO-d6):δ 11.73 (s, br., 1H), 7.76 (dt, J = 8.0, 1.0 Hz, 1H), 7.67 (qd, J = 8.1, 1.2 Hz, 1H), 7.24 (dt, J = 4.6, 3.3 Hz, 1H).