General procedure for the synthesis of 5-methoxy-3-piperidin-4-yl-1H-indole from 5-methoxy-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole: Intermediate 36 (47.0 g, 0.21 mol) was dissolved in ethanol (500 mL) and 10% Pd/C catalyst (4 g) was added. The hydrogenation reaction was carried out at atmospheric pressure for 24 hours. After completion of the reaction, the mixture was filtered through diatomaceous earth and the filtrate was concentrated by evaporation to give 5-methoxy-3-piperidin-4-yl-1H-indole (45.54 g, 0.2 mol) as an orange solid in 96% yield. The product was characterized by 1H NMR (CDCl3, 300 MHz): δ 7.4 (d, 1H), 7.3 (bd, 1H), 7.1 (s, 1H), 7.0 (dd, 1H), 4.0 (s, 3H), 3.4 (dd, 2H), 2.9-3.0 (m, 3H), 2.2 (m, 2H), 1.9 (m, 2H).
