8-Chloro-2-methyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole (0.5 g, 0.0022 mol) was dissolved in N-methyl 2-pyrolidone (4.0 mL). Powdered potassium hydroxide (1 g, 0.008 mol) was added and heated at 100° C. for 2 h. 4-(2-Bromo-ethyl)-2-fluoro-1-methoxy-benzene (0.520 g, 0.0022 mol) was added at the room temperature and stir for 0.5 h at RT (TLC showed incomplete reaction). Reaction mixture was diluted with water (200 mL) and extracted with ethyl acetate (3×100 mL). Organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure using rotary evaporator. The crude was purified through column chromatography (4% MeOH:DCM in silica 100-200 mesh, Diameter of column—2.5 cm, Height of silica—approx. 5 inch) to provide the desired compound as light yellow oil (0.038 g, 4% yield). 8-Chloro-5-[2-(3-fluoro-4-methoxy-phenyl)-ethyl]-2-methyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole (0.038 g, 0.00010 mol) was dissolved in THF (1.0 mL). A solution of oxalic acid dihydrate (0.012 g, 0.00010 mol) in THF (1.0 mL) was added and stirred for 30 min at RT. The precipitate was filtered and dried to give oxalate salt as off white solid (0.016 g, 34% yield).
