Efficient, environmentally benign, one-pot procedure for the synthesis of 1,5-benzodiazepine derivatives using N-methyl-2-pyrrolidonium hydrogen sulphate as an ionic liquid catalyst under solvent-free conditions

Abstract

A powerful and environmentally benign method has been developed for the one-pot synthesis of 4-substituted-1,5-benzodiazepines via the three-component reaction of a series of aldehydes with dimedone and o-phenylenediamine using [H-NMP][HSO4] as a Brönsted acidic ionic liquid catalyst under solvent-free conditions. The key benefits of this new method over existing techniques include high yields, the use of a green catalyst, short reaction times and facile catalyst separation.