Reaction Steps
To a solution of 5-bromobenzothiophene (511 mg, 2.4 mmol) at −75° C., was added t-butyllithium (1.7 M in pentane, 1.6 mL, 2.6 mmol) dropwise. The reaction mixture was stirred at −75° C. for 1 hour. To the resulting dark brown mixture was added 2-methyl-2,3-dihydro-1H-isoquinolin-4-one (323 mg, 2.0 mmol), which was prepared using the method described by Hanna et al., J. Med. Chem., 17(9):1020-1023 (1974), which is hereby incorporated by reference in its entirety. The reaction mixture was stirred for 15 hours with gradual warming up. The mixture was quenched with saturated ammonium chloride and extracted with ethyl acetate (3×50 ml). The combined organic extracts were washed with saturated sodium chloride, dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. Purification by medium pressure silica gel chromatography (10-40% ethyl acetate/hexanes) followed by preparative HPLC afforded 4-(benzo[b]thiophen-5-yl)-2-methyl-1,2,3,4-tetrahydro-isoquinoline-4-ol (65 mg, 11%) and 4-(5-bromobenzo[b]thiophen-2-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol (58 mg, 8%). 4-(Benzothiophen-5-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol: 1H NMR (CDCl3, 500 MHz) δ 7.81 (d, J=8.5 Hz, 1H), 7.69 (d, J=8.5 Hz, 1H), 7.34-7.23 (m, 4H), 7.20 (s, 1H), 7.18 (d, J=7.3 Hz, 1H), 7.10 (d, J=7.6 Hz, 1H), 3.91 (s, 1H), 3.84 (d, J=15.0 Hz, 1H), 3.53 (d, J=15.0 Hz, 1H), 3.11 (dd, J=11.6, 1.4 Hz, 1H), 2.87 (d, J=11.6 Hz, 1H), 2.50 (s, 3H); ESI MS m/z=296 [M+H]+. 4-(5-Bromobenzothiophen-2-yl)-2-methyl-1,2,3,4-tetrahydroisoquinoline-4-ol: 1H NMR (CDCl3, 300 MHz) δ 7.81 (d, J=1.8 Hz, 1H), 7.66 (d, J=8.5 Hz, 1H), 7.38 (dd, J=8.5, 1.9 Hz, 1H), 7.30-7.23 (m, 2H), 7.18 (d, J=7.3 Hz, 1H), 7.11 (s, 1H), 7.07 (d, J=7.6 Hz, 1H), 3.69 (d, J=15.0 Hz, 1H), 3.48 (d, J=15.0 Hz, 1H), 3.10 (dd, J=11.6, 1.3 Hz, 1H), 2.83 (d, J=11.6 Hz, 1H), 2.47 (s, 3H); ESI MS m/z=374 [M+H]+.
