[Cl:1][C:2]1[CH:15]=[CH:14][C:5]2[N:6]([CH2:12][CH3:13])C(=O)[O:8][C:9](=[O:10])[C:4]=2[CH:3]=1.Cl>[OH-].[K+]>[Cl:1][C:2]1[CH:15]=[CH:14][C:5]([NH:6][CH2:12][CH3:13])=[C:4]([CH:3]=1)[C:9]([OH:10])=[O:8]150 mg (0.67 mmol) of 6-chloro-1-ethyl-1H-benzo[d][1,3]oxazine-2,4-dione were suspended in 1.33 ml of 2N KOH and the mixture was heated to 95° C. for 2 h. After cooling to RT the pH was adjusted to 5-6 by careful addition of 1N HCl. The precipitate was then filtered off, washed with water and dried to give 93 mg (71%) of 5-chloro-2-ethylamino-benzoic acid as a yellow solid. 1HNMR (DMSO-d6, 300 MHz): δ 1.13 (t, J=7.2 Hz, 3H), 3.12 (q, J=7.2 Hz, 2H), 6.68 (d, J=9.1 Hz, 1H), 7.31 (dd, J=9.1 and 2.7 Hz, 1H), 7.64 (d, J=2.7 Hz, 1H).
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