Hydrochloric Acid → HCID 20766264, compound

Participants

Reaction Conditions

Reaction Steps

5.6 ml of concentrated hydrochloric acid are added to a solution of 1.2 g of (R)-2-benzyloxy-1-(2-isopropyl-2,3-dihydroindol-1-yl)propan-1-one diastereoisomer (2) in 34 ml of absolute ethanol. The reaction mixture is microwave-heated at 120° C. for 1 hour, and is then cooled to ambient temperature and concentrated to dryness under reduced pressure. The residue is taken up in 100 ml of water and is then alkalinized with concentrated sodium hydroxide. The mixture is extracted with 2×120 ml of dichloromethane. The organic phases are combined, washed with water, dried over magnesium sulfate, filtered, and then concentrated to dryness under reduced pressure. The residue is purified by chromatography on a 70 g cartridge of 15-40 μm silica, elution being carried out with pure cyclohexane and then with a 95/5 v/v cyclohexane/ethyl acetate mixture at a flow rate of 50 ml/min, and then on a 30 g cartridge of 15-40 μm silica, elution being carried out with a 98/2 cyclohexane/ethyl acetate mixture, at a flow rate of 30 ml/min. 0.26 g of (+)-2-isopropylindoline is thus obtained in the form of a colorless oil, the characteristics of which are the following:

Provenance & Evidence