Water → 2-Methyl-2,3-dihydro-1H-indol-4-ol

Participants

Reaction Conditions

Reaction Steps

1.35 g of sodium cyanoborohydride are gradually added to a solution of 1 g of 4-hydroxy-2-methylindole in 35 ml of acetic acid under argon cooled to a temperature of about 14° C. The reaction mixture is stirred at a temperature of about 14° C. for 15 minutes, and is then allowed to warm up to ambient temperature. After 1.5 hours, the reaction mixture is treated with 15 ml of water, stirred at ambient temperature for 1 hour, and then concentrated to dryness under reduced pressure. The residue is taken up in 75 ml of ethyl acetate and then treated with 60 ml of a saturated sodium hydrogen carbonate solution. After stirring for 1 hour and then settling out, the organic phase is separated and the aqueous phase is extracted with 50 ml of ethyl acetate. The organic phases are combined, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered, and then concentrated to dryness under reduced pressure. The residue is purified on a 70 g cartridge of 15-40 μm silica, elution being carried out with an 80/20 v/v cyclohexane/ethyl acetate mixture, with a flow rate of 80 ml/min. 0.87 g of 4-hydroxy-2-methylindoline is thus obtained in the form of a yellow oil, the characteristics of which are the following:

Provenance & Evidence