Hydrochloric Acid → 2-Amino-4-oxo-3H-indolo[2,3-d]pyrimidine

Participants

Reaction Steps

A mixture of 2-guanidinoindole-3-carboxylic acid ethyl ester hydrochloride (1.00 g, 3.5 mmol) and sodium hydroxide (1.5 g) in water (50 mL) is heated to gentle reflux for 6 hr followed by the addition of sufficient 5% HCl to adjust the solution to pH 1, and filtration of the resulting mixture through celite, washing the pad with water. The filtrate is extracted with ethyl acetate (3×25 mL), and then basified with solid sodium carbonate. The tan precipitate which slowly forms is collected by filtration, washed with water, and dried in vacuo affording 2-amino-4-oxo-3H-indolo[2,3-d]pyrimidine (561 mg, 78%) as light tan crystals, mp >275 C.

Provenance & Evidence