0.94 M solution of diisobutylaluminium hydride in hexane (2.73 ml) was added dropwise to a solution of ethyl 6-{[(3R)-1-benzyl-3-pyrrolidinyl]amino}-5-fluoronicotinate (294 mg) in THF (10 ml) with stirred below 5° C. under atmospheric pressure of nitrogen, and the reaction mixture was stirred at the same temperature for 1.5 hrs. To the reaction mixture was added saturated aqueous ammonium chloride (0.727 ml) below 5° C., then the mixture was stirred at 25° C. for 30 minutes. Na2SO4 (2.87 g) was added to the solution, and the mixture was stirred at 25° C. for 15 minutes. The reaction mixture was filtrated, the filtrate was evaporated in vacuo. Toluene (15 ml) was added to the residue, and the mixture was evaporated in vacuo. The resulting residue and activated MnO2 (744 mg) in ethyl, acetate (20 ml) were stirred at 75° C. for 1 hour. After removal of the insoluble material by filtration, the filtrate was evaporated in vacuo to give 6-{[(3R)-1-benzyl-3-pyrrolidinyl]amino}-5-fluoronicotinaldehyde (250 mg, 98%) as syrup. The compound was used in the next step reaction without purification.
