To a solution of 6-bromo-8-piperazin-1-yl-quinoline (610 mg, 2.09 mmol), 4-(5-fluoro-1-methyl-1H-indol-3-yl)-cyclohexanone (510 mg, 2.09 mmol), and sodium triacetoxyborohydride (660 mg, 3.14 mmol) in dichloroethane (40 mL) was added acetic acid (0.24 mL, 4.18 mmol) and stirred overnight at room temperature. The reaction was quenched with 1 M NaOH (50 mL) and H2O (100 mL) then extracted in CH2Cl2 (100 mL) and EtOAc (100 mL). The organic fractions were combined, dried over Na2SO4, concentrated, filtered and chromatographed (5% MeOH/EtOAc). The majority of the cis compound precipitated out of 5% MeOH/EtOAc before application to the column and was purified by filtration affording 510 mg (47%) of the cis isomer as a pale yellow solid: mp 215-217° C.
