Eco-friendly synthesis of 1,4-benzodiazepine-2,5-diones in the ionic liquid [bmim]Br

Abstract

The green reaction of isatoic anhydrides with alpha-amino acids in presence of the ionic liquid 1-butyl-3-methylimidazolium bromide afforded 1,4-benzodiazepine-2,5-diones in excellent yields in absence of a catalyst. The reaction workup is simple and the ionic liquid was easily recovered from the reaction and reused. The methodology was quite general and a range of cyclic and acyclic alpha-amino acids were examined to produce 1,4-benzodiazepine-2,5-diones.