methyl 1H-indole-5-carboxylate → methyl 2,3-dihydro-1H-indole-5-carboxylate

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Reaction Steps

To a cold solution of methyl indole-5-carboxylate (2 g, 11.4 mmol) in glacial acetic acid at 0° C. (15 ml) sodium cyanoborohydride (1.075 g, 17.1 mmol) was slowly added. The mixture was allowed to warm-up and stirred at room temperature for one more hour, cooled again to 0° C. and quenched with H2O. The pH of the resultant solution was adjusted to the value of 12 by adding aqueous NaOH, extracted with DCM, washed with brine and dried over MgSO4. The dried extract was concentrated in vacuum and purified by flash chromatography (eluent 30% EtOAc in hexane) to give the title compound 20 (1.62 g, 80%) as a beige solid. 1H-NMR (DMSO) δ: 2.94 (t, J=8.6 Hz, 2H); 3.51 (dt, J=1.2, 8.6 Hz, 2H); 3.71 (s, 3H); 6.42 (d, J=8.0 Hz, 2H); 7.54 (m, 2H).

Provenance & Evidence