7-(4-fluorobenzyloxy)-2,3-dimethyl-1H-pyrrolo[3,2-b]pyridine (25 mg, 0.105 mmol) prepared in Step 1, potassium tert-butoxide (13.6 mg, 0.163 mmol), and a catalytic amount of 18-crown-6 were added to anhydrous tetrahydrofuran (2 ml). 4-Chlorobenzyl chloride (0.089 ml, 0.160 mmol) was added to the reaction mixture, which was then stirred for 12 hours at room temperature. The reaction mixture was concentrated under reduced pressure. The resulting residue was purified with silica gel column chromatography (ethyl acetate/methylene chloride/methanol=10/10/1, (v/v/v)), dissolved in ethyl acetate (1 ml), and then saturated with hydrochloric acid gas. The resulting precipitate was filtered to give the titled compound as a white solid (6.9 mg, 15.8%).
