Dimethylformamide → 1H-Indole-3-carboxylic acid, 1,1-dimethylethyl ester

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Reaction Steps

1.00 g (6.21 mmol) indole-3-carboxylic acid is dissolved in 150 ml absolute THF, mixed with 0.05 g (0.68 mmol) absolute DMF as well as with 1.48 g (12.5 mmol) thionylchloride and stirred at room temperature for 1 hour. Following the drop-wise addition of 2.51 g (24.8 mmol) tiethylamine and of 9.20 g (124 mmol) tert-butanol and heating under reflux for 2 hours, hydrolysis of the cooled reaction mixture is carried out in water. Three extractions with diethyl ether, concentration to half the volume on the rotary evaporator, washing with 5% sodium carbonate solution and with saturated NaCl solution, drying on sodium sulfate, filtration and reconcentration on the rotary evaporator leave as a crude product a brown oil which is purified on silica gel by means of column chromatography (flow agent: petroleum ether/ethyl acetate 90:10) and yields the product as a yellow oil.

Provenance & Evidence