Trifluoroacetic acid → 5-nitro-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole

Participants

Reaction Steps

A solution of tert-butyl 4-(5-nitro-1H-indol-3-yl)-5,6-dihydropyridine-1(2H)-carboxylate (0.8 g, 2.330 mmol) in CH2Cl2 (16 mL) was treated with TFA (4 mL) at 0° C. and the resulting mixture was stirred at same temperature for 3 h. The reaction was evaporated and crude was basified with 1 N NaOH solution (pH ˜14). The solid was filtered off, washed with water (2×10 mL). The crude was dried under vacuum and treated with 10% ethyl acetate in hexanes (20 mL). The solid was filtered and washed with hexanes (2×5 mL). The yellow solid was dried under vacuum to obtain 5-nitro-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole (0.56 g, 99%). 1H NMR (DMSO-d6) δ 8.69 (d, 1H, J=2.1 Hz), 8.00 (dd, 1H, J=2.1, 9.0 Hz), 7.63 (s, 1H), 7.55 (d, 1H, J=9.0 Hz), 6.21 (s, 1H), 3.42-3.30 (m, 2H, merged with DMSO-peak), 2.93 (t, 2H, J=5.4 Hz), 2.40-2.30 (m, 2H); ESI-MS (m/z, %): 244 (MH+, 77), 215 (100).

Provenance & Evidence