2,2'-Bipyridine → 4-{2-[5-(2-Aminomethyl-4-fluorophenoxy)-indazol-1-yl]-ethyl}-piperazine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a solution of 4-{2-[5-(2-cyano-4-fluorophenoxy)-indazol-1-yl]-ethyl}-piperazine-1-carboxylic acid tert-butyl ester (0.160 g, 0.344 mmol), CoBr2 (0.008 g, 0.034 mmol), [2,2′]bipyridinyl (0.016 g, 0.010 mmol) in EtOH (6 mL) was added NaBH4 (0.039 g, 1.0 mmol). The mixture was stirred for 3 hours at room temperature. The reaction was quenched with MeOH (3 mL) and acetic acid (10 drops). The solution was concentrated under reduced pressure and diluted with ethyl acetate. The mixture was washed with aqueous NaHCO3, brine, dried over MgSO4, and concentrated under reduced pressure. The crude oil was chromatographed eluting with 1% triethylamine in ethyl acetate, MeOH/CH2Cl2/hexanes (1:15:15, 1% triethylamine), then MeOH/CH2Cl2/hexanes (1:10:10, 1% triethylamine). The pure product was obtained in 86% yield.

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