C([O:3][C:4]([CH:6]1[C:18]2[C:17]3[C:12](=[CH:13][CH:14]=[CH:15][CH:16]=3)[N:11]([CH2:19][CH2:20][F:21])[C:10]=2[CH2:9][CH2:8][CH2:7]1)=[O:5])C.[OH-].[Na+]>C(O)C.O>[F:21][CH2:20][CH2:19][N:11]1[C:10]2[CH2:9][CH2:8][CH2:7][CH:6]([C:4]([OH:5])=[O:3])[C:18]=2[C:17]2[C:12]1=[CH:13][CH:14]=[CH:15][CH:16]=29-(2-Fluoro-ethyl)-2,3,4,9-tetrahydro-1H-carbazole-4-carboxylic acid ethyl ester (30) (380 mg, 1.3 mmol) was dissolved in ethanol (3 mL) and then NaOH (520 mg) in water (5 mL) was added. The reaction was heated at reflux for 2 h. The reaction was concentrated in vacuo and the residue diluted with water and washed with dichloromethane (2×50 mL). The aqueous layer was added drop wise to 2 N HCl (50 mL) and then extracted into dichloromethane (3×50 mL). The organics were dried and concentrated in vacuo to afford 130 mg (37%) of 9-(2-fluoro-ethyl)-2,3,4,9-tetrahydro-1H-carbazole-4-carboxylic acid (31) as a yellow solid which was used in the next step without purification. The structure was confirmed by 1H NMR (300 MHz, CDCl3) δ 1.90-2.42 (4H, m, 2- and 3-CH2), 2.60-2.91 (2H, m, 1-CH2), 3.94 (1H, t, J=6 Hz, 4-CH), 4.30 (1H, t, J=6 Hz, NCH2CH2F), 4.37 (1H, t, J=6 Hz, NCH2CH2F), 4.59 (1H, t, J=6 Hz, NCH2CH2F), 4.74 (1H, t, J=6 Hz, NCH2CH2F), 7.05-7.26 (3H, m, ArH), 7.59 (1H, d, J=9 Hz, ArH).
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