To a stirred solution of 1 (3.00 g, 15.77 mmol) and tryptamine (2.78 g, 17.35 mmol) in anhydrous 1,2-dichloroethane (200 mL) under nitrogen was added NaBH(OAc)3 (3.87 g, 17.35 mmol) at room temperature. The reaction mixture was stirred at room temperature for 39 hours, poured into 10% solution of K2CO3 and extracted with CH2Cl2. The organic layer was concentrated to form a residue which was purified by flash chromatography on silica gel (MeOH/CH2Cl2, 10/90) and co-precipitated in a mixture of AcOEt/hexane to afford the title compound 2 (4.39 g, 13.13 mmol, 83% yield) as a yellow solid. 1H NMR (400 MHz, DMSO-d6) δ(ppm): 10.78 (s, 1H), 7.70-7.62 (m, 3H), 7.49 (d, J=8.0 Hz, 1H), 7.39 (d, J=8.2 Hz, 2H), 7.33 (dt, J=8.0, 0.9 Hz, 1H), 7.13 (d, J=2.2 Hz, 1H), 7.06 (ddd, J=7.0, 7.0, 1.2 Hz, 1H), 6.96 (ddd, J=6.9, 6.9, 1.1 Hz, 1H), 6.62 (d, J=16.0 Hz, 1H), 3.79 (s, 2H), 3.75 (s, 3H), 2.91-2.78 (m, 4H), 2.18 (bs, 1H).
