Pentane → 6-Fluoro-9-(4-fluorobenzyl)-1,2,3,9-tetrahydro-4H-carbazol-4-one

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Reaction Steps

6-Fluoro-1,2,3,9-tetrahydro-4H-carbazol-4-one (0.3940 g, 0.0019 mol) is added to a slurry of pentane-washed NaH (0.0966 g, 0.0024 mol) in DMF (3 mL) and after stirring for 10 min, p-fluorobenzyl bromide (0.29 mL, 0.0023 mol) is added. After stirring for 4 h at room temperature, the mixture is partitioned between water and ethyl acetate. The combined organic layers are dried over sodium sulfate and concentrated to dryness. The resulting solids are chromatographed on silica gel (100 mL) using methanol/dichloromethane (0.5/99.5) to give 0.5678 g (94%) of the title compound. An aliquot is recrystallized from ethyl acetate/heptane; mp 182.5-183° C.; MS (ESI+) for C19H15F2NO m/z 312.2 (M+H)+; IR (drift) 1631, 1511, 1483, 1466, 1449, 1256, 1228, 1218, 1137, 1094, 867, 836, 813, 808, 802 cm−1; 1H NMR (CDCl3) δ2.24, 2.58, 2.86, 5.28, 6.94, 7.13, 7.96. Anal. Calcd for C19H15F2NO: C, 73.30; H, 4.86; N, 4.50. Found: C, 73.27; H, 4.92; N, 4.54.

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