Trifluoroacetic acid → 1-Methyl-4-nitro-2,3-dihydro-1H-indole

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Reaction Steps

To a stirred solution of 1-methyl-4-nitro-1H-indole (3.8 g, Organic Process Research and Development 2001 5 (6) 604) and borane-tetrahydrofuran complex (1M in tetrahydrofuran, 86.3 ml) at 0° C. under an atmosphere of nitrogen was added, dropwise, trifluoroacetic acid (88 ml). The resulting mixture was allowed to warm to room temperature and stirred at room temperature for 90 min. The mixture was cautiously added to 2M sodium carbonate solution (750 ml) over 20 min and then stirred for 30 min. The mixture was extracted with ethyl acetate (2×300 ml), the combined organic extracts were dried over sodium sulphate and the solvent was removed in vacuo. Purification by column chromatography on silica gel, eluting with hexane : ethyl acetate (9:1) gave the title compound as a red solid (1.97 g).

Provenance & Evidence