Ammonia → 4-fluoro-2-methyl-2,3-dihydro-1H-indole

Participants

Reaction Conditions

Reaction Steps

3.63 g of sodium cyanoborohydride are gradually added to a solution of 2.87 g of 4-fluoro-2-methylindole in 98 ml of acetic acid under argon cooled to a temperature of about 14° C. The reaction mixture is allowed to warm up to ambient temperature. After 2 hours, the reaction mixture is poured into a mixture of water and ice, and is then treated with a 28% aqueous ammonia solution until the pH is 9. The mixture is then extracted twice with dichloromethane. The organic phases are combined, dried over anhydrous magnesium sulfate, filtered, and then concentrated to dryness under reduced pressure. The residue is purified on a 300 g silica column, elution being carried out with a 100/0 to 90/10 v/v heptane/ethyl acetate gradient. 2.19 g of 4-fluoro-2-methyl-2,3-dihydro-1H-indole are thus obtained in the form of a colorless oil, the characteristics of which are the following:

Provenance & Evidence