Methyl indole-7-carboxylate → (1H-indol-7-yl)methanol

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Reaction Steps

Indole-7 carboxyldehyde (K-44). Methyl 7-indolecarboxylate was prepared according to literature procedure {Batcho B. and Leimgruber, K., Org. Syn. Vol IIV, page 34-40). To a solution of methyl 7-indolecarboxylate (13 g, 74.2 mmol) in anhydrous THF (250 mL) was added LiAlH4 (10.9 g, 0.288 mol) in portions, and reaction mixture was heated to reflux for 2 h. After cooling to room temperature, the excess hydride was quenched by addition of water (12mL), 15% NaOH (12 mL) and water (26 mL). The solids were removed by filtration through a pad of Celite and filtrate was evaporated in vacuo to yield (1H-indol-7-yl)-methanol (10.7 g, 98%). 1HNMR (CDCl3). To a solution of the alcohol, (1H-indol-7-yl)-methanol (8.0 g, 54.3 mmol) in 400 mL of methylene chloride was added activated manganese (IV) oxide (85%, 41.0 g, 0.40 mol), and stirred at ambient temperature for 72 h. After additional of 200 mL of methylene chloride and 400 mL of methanol to the reaction mixture, the whole mixture was filtered through a pad of silica gel to remove solid materials. The filtrate was concentrated to afford a crude product, which was purified by a column chromatography on silica gel to yield 1H-indole-7-carbaldehyde, K-44 (6.55 g, 83%).

Provenance & Evidence