Potassium Hydroxide → 8-Isopropyl-2-methyl-5-[2-(6-trifluoromethyl-pyridin-3-yl)-ethyl]-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole

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Reaction Steps

To a solution of 8-Isopropyl-2-methyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole (0.1 g, 0.43 mmol) in N-methyl 2-pyrolidone (0.05 mL) was added powdered potassium hydroxide (0.096 g, 1.72 mmol) and al lowed to stir for 10 min at RT. 2-trifluoromethyl-5-vinyl pyridine (0.19 g, 1.1 mmol) was added and stirred for further at 35 deg C. for 3 h. Reaction mixture was diluted with brine (5 mL) and extracted with ethyl acetate (3×50 mL). The organic layer was dried over anhydrous sodium sulphate and concentrated under reduced pressure. The crude was purified through column chromatography (5% 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 brown oil (0.17 g, 45% yield). Isopropyl-2-methyl-5-[2-(6-trifluoromethyl-pyridin-3-yl)-ethyl]-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole (0.080 g, 0.19 mmol) was dissolved in THF (2.0 mL). A solution of oxalic acid dihydrate (0.01 7 g, 0.19 mmol) in THF (2 mL) was added and stirred for 30 min at RT, Precipitate obtained was filtered and dried to give oxalate salt as white solid (0.045 g, 46% yield).

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