Diammonium hydrogen phosphate → 5-Bromo-3-cyanoindole

Participants

Reaction Steps

A mixture of 5-bromo-indole-3-carboxaldehyde (5 g, 22.3 mmol), diammonium hydrogen phosphate (15.6 g, 31.8 mmol) in 1-nitropropane (66 mL) and acetic acid (22 mL) were heated at reflux for 16 h. After cooling to room temperature, the solvents were removed under reduced pressure and water added to the dark residue. After a short while, 5-bromo-1H-indole-3-carbonitrile precipitated rapidly. The solid was filtered, washed severally with water and dried for several hours to afford 4.3 g (86%) of the desired product. 1H-NMR (CD3OD) δ 7.40 (m, 2H), 7.77 (s, 1H), 7.97 (s, 1H). Mass spec.: 222.95 (MH)+.

Provenance & Evidence