Sodium borohydride → Ethyl 1-(2-Aminoethyl)-6,6-difluoro-4,5,6,7-tetrahydro-1H-indole-2-carboxylate

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Reaction Steps

Into a 100-mL round-bottom flask was placed a solution of 113m (3.3 g, 12.30 mmol, 1.00 equiv) in ethanol (30 mL) and NiCl2.6H2O (3.2 g, 13.45 mmol, 1.10 equiv), followed by the addition of NaBH4 (1.4 g, 37.01 mmol, 3.00 equiv) in several batches at 0° C. (FIG. 14). The resulting solution was stirred at room temperature for 24 h. The solids were filtered out and the filtrate was concentrated under vacuum. The resulting solution was diluted with 30 mL of ethyl acetate and washed with 1×30 mL of hydrogen chloride (2/V). The solution was adjusted to pH=9 with saturated aqueous sodium bicarbonate and extracted with 2×30 mL of ethyl acetate. The combined organic layers were dried over anhydrous sodium sulfate and concentrated under vacuum to afford 0.7 g (21%) of 113n as a light yellow oil.

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