4-Chloropyridine hydrochloride → 3-(4-Pyridinylamino)-1H-indole-2-carboxylic acid ethyl ester

Participants

Reaction Steps

A solution ethyl 3-aminoindole-2-carboxylate (4.94 g, 24.2 mmole) and 4-chloropyridine hydrochloride (3.63 g, 24.2 mmole) in 70 mL of 1-methyl-2-pyrrolidinone was heated at 165° C. for 6 hours. The reaction mixture was then quenched into water and the aqueous phase was washed with ethyl acetate. After basification with a potassium carbonate solution, a solid was filtered, rinsed with water and ether and dried to give 4.13 g of a brown solid. A 2.2 g portion was recrystallized from methanol (charcoal treatment) to give 1.40 g of an off-white solid, mp: 248-250° C. (dec.)

Provenance & Evidence