Isobutyraldehyde → (R)-Methyl 3-(isobutylamino)-2,3-dihydro-1H-indene-5-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of (R)-methyl 3-amino-2,3-dihydro-1H-indene-5-carboxylate (A-07) (5.23 mmol, 1 eq) in MeOH (50 ml) there were added first acetic acid (2 drops) and then, at 0° C., isobutyraldehyde (0.47 ml, 5.23 mmol, 1 eq), and stirring was carried out for 1 h at RT. The reaction mixture was cooled to 0° C. again, NaCNBH3 (821 mg, 13.07 mmol, 2.5 eq) was added, and stirring was carried out for a further 30 min at RT. After monitoring by thin-layer chromatography, the reaction mixture was concentrated, and the residue was taken up in water (50 ml) and extracted with dichloromethane (2×75 ml). The combined organic phases were washed with sat. NaCl solution (2×60 ml), dried over sodium sulfate and concentrated under reduced pressure. After purification by column chromatography (Alox neutral, 3% MeOH in dichloromethane), the desired product was obtained. Yield: 65% (0.850 g, 33.44 mmol).

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