To a stirred solution of 4-hydroxy-piperidine-1-carboxylic acid tert-butyl ester (227 mg, 1.13 mmol) in THF (4.0 mL) at room temperature was added NaH (100 mg, 4.5 mmol). Stirring was continued for 10 min. To this solution was added 4-(4-benzyloxy-phenyl)-3-butyl-6-chloro-pyridazine (200 mg, 0.56 mmol) and the resulting mixture was stirred at 50-55° C. overnight. The reaction was poured into water and extracted with ethyl acetate. The organic layer was washed with water followed by brine, dried (Na2SO4), filtered, and concentrated under reduced pressure. The crude product was purified by flash silica gel column chromatography using 30% ethyl acetate in hexanes to provide 4-[5-(4-benzyloxy-phenyl)-6-butyl-pyridazin-3-yloxy]-piperidine-1-carboxylic acid tert-butyl ester.
