Potassium Hydroxide → (E)-6-fluoro-2-methyl-5-(2-(pyridin-4-yl)prop-1-enyl)-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole

1-(6-Fluoro-2-methyl-3,4-dihydro-1H-pyrido[4,3-b]indol-5(2H)-yl)-2-(pyridin-4-yl)propan-2-ol (510 mg, 1.5 mmol) was dissolved in thionylchloride (5 mL) and stirred at RT for 2 h. The reaction mixture was concentrated under reduced pressure. The residue was dissolved in N-methyl-2-pyrrolidone (3 mL) and stirred for 5 min. at RT. Powdered KOH (616 mg, 10 mmol) was added, and the stirring was continued for additional 10 min. The reaction mixture was heated at 100° C. for 2 h. The progress of reaction was monitored by TLC and NMR. The reaction mixture was diluted with water and extracted with EtOAc, washed with water, concentrated to obtain the crude product which was purified by HPLC. 1H NMR (DMSO-d6, TFA salt) δ (ppm): 8.80 (d, 2H), 8.0 (d, 2H), 7.70 (s, 1H), 7.40 (d, 1H), 7.30 (m, 1H), 7.10 (m, 1H), 4.80 (m, 1H), 4.30 (m, 1H), 3.80 (m, 2H), 3.10 (m, 2H), 3.0 (s, 3H), 2.0 (s, 3H).