Hydrochloric Acid → Methyl 2,3-dihydro-1H-indole-7-carboxylate

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Reaction Steps

1.75 g of indole-7-carboxylic acid methyl ester and 2.92 g of borane-trimethylamine complex are dissolved in 10 ml of dioxane. To the resulting solution, 2 ml of concentrated hydrochloric acid are added. The reaction solution is heated under reflux for 30 minutes, and then cooled to room temperature. 10 ml of 6N hydrochloric acid are added to the reaction solution, which is then refluxed under heating for 15 minutes, and thereafter cooled to room temperature. The reaction solution is poured into 50 ml of water. The resulting mixture is neutralized with a 2N aqueous sodium hydroxide solution, and then extractd with ether. The organic layer is washed with a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate. After the solvent has been distilled off, 1.26 g of 2,3-dihydroindole-7-carboxylic acid methyl ester are obtained, mp. 70° to 73° C.

Provenance & Evidence