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

Reaction equation

Cl.C([O:4][C:5]([C:7]1[C:15]2[C:10](=[CH:11][CH:12]=[CH:13][CH:14]=2)[NH:9][C:8]=1[NH:16][C:17]([NH2:19])=[NH:18])=O)C.[OH-].[Na+].Cl>O>[NH2:18][CH:17]1[N:16]=[C:8]2[N:9]=[C:10]3[C:15]([CH:14]=[CH:13][CH:12]=[CH:11]3)=[C:7]2[C:5](=[O:4])[NH:19]1

Participants

Procedure

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.