4-Fluoroisatoic anhydride is prepared from 6-fluoroindole (9h) by stirring in a 4:1 mixture of CH3CN/H2O for 1 h at 40℃.1H NMR (DMSO-d6): δ11.87 (s, br., 1H), 8.00 (ddd, J = 8.8, 6.0, 0.8 Hz, 1H), 7.11 (tdd, J = 8.8, 2.5, 1.1 Hz, 1H), 6.88 (ddd, J = 0.8, 2.5, 9.6, 2.5, 0.8 Hz, 1H).
