Trifluoroacetic acid → 6-Bromo-8-(2,4-dichlorophenyl)-2,3,4,4a,5,9b-hexahydro-1h-pyrido[4,3-b]indole

A 100 mL round bottom flask was charged with a solution of di(tert-butyl) 6-bromo-8-(2,4-dichlorophenyl)-3,4,4a,9b-tetrahydro-1H-pyrido[4,3-b]indole-2,5-dicarboxylate (0.27 g, 0.45 mmol) in CH2Cl2 (5 mL) and cooled to 0° C. with an ice bath. Trifluoroacetic acid (5 mL) was added via pipette, the ice bath was removed, and the mixture was stirred at ambient temperature for 1.5 hours. The reaction was then concentrated in vacuo, and the residue was partitioned between 5 N NaOH and ethyl acetate (2X). The organics were combined, dried with MgSO4, filtered and concentrated to give 280 mg of a crude yellow oil. The crude was purified on a 40 g silica Biotage column using 5% methanol in CH2Cl2 as the eluent to give 151 mg (85%) of 6-bromo-8-(2,4-dichlorophenyl)-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b]indole as a white foam: 1H NMR (300 MHz, CDCl3) δ 7.47 (d, J=2 Hz, 1 H), 7.26 (m, 3 H), 7.10 (s, 1 H), 4.08 (m, 2 H), 3.28 (m, 1 H), 3.14-2.86 (m, 4 H), 1.93-1.80 (m, 3 H); IR (diffuse reflectance) 2937, 2851, 1615, 1572, 1460, 1359, 1314, 1303, 1237, 1102, 1032, 869, 816, 761, 744 cm−1. OAMS supporting ions at: ESI+398.8; HRMS (FAB) calcd for C17H15BRCL2N2 +H1 396.9874, found 396.9867.