5-Hydroxymethyl-2-(2-oxo-1,2-dihydro-quinolin-3-yl)-indole-1-carboxylic acid tert-butyl ester → 5-Formyl-2-(2-oxo-1,2-dihydro-quinolin-3-yl)-indole-1-carboxylic acid tert-butyl ester

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Reaction Conditions

Reaction Steps

The pre-activated MnO2 (34.5 g, 15 equiv) and the alcohol (1-8, 10.32 g, 1.0 equiv) were weighed into a 1-liter flask and suspended in dry dichloromethane (500 mL). The reaction mixture was heated to 45° C. and was complete by thin layer chromatography after 1 hour. The mixture was allowed to cool to ambient temperature and the manganese oxide(s) were removed by vacuum filtration. The resulting pad of oxides on the filter were triturated with hot THF and the solvent filtered through under vacuum to remove any product from the oxides. The resulting filtrate was concentrated in vacuo to afford the crude aldehyde as a yellow solid. The solid was triturated with methanol (10 mL) and ethyl acetate (15 mL) followed by vacuum filtration to isolate the pure product. The light-yellow aldehyde was dried under vacuum (1-9). 1H NMR (500 MHz, DMSO-d6) δ 12.15 (s, 1H), 10.08 (s, 1H), 8.26 (d, 1H, J=1.5 Hz), 8.24 (d, 1H, J=8.5 Hz), 8.15 (s, 1H), 7.90 (dd, 1H, J=8.5, 1.5 Hz), 7.77 (d, 1H, J=7.5 Hz), 7.55 (m, 1H), 7.37 (d, 1H, J=8.5 Hz), 7.24 (m, 1H), 7.01 (s, 1H).

Provenance & Evidence