The Debus–Radziszewski imidazole synthesis is a multi-component reaction used for the synthesis of imidazoles from a 1,2-dicarbonyl, an aldehyde, and ammonia or a primary amine.
In the first stage, the dicarbonyl and two ammonia molecules condense with the two carbonyl groups to give a diimine: In the second stage, this diimine condenses with the aldehyde: However, the actual reaction mechanism is not certain.
[2][3] This reaction is named after Heinrich Debus[4] and Bronisław Leonard Radziszewski [de].
[5][6] A modification of this general method, where one equivalent of ammonia is replaced by an amine, affords N-substituted imidazoles in good yields.
[3] This reaction has been applied to the synthesis of a range of 1,3-dialkylimidazolium ionic liquids by using various readily available alkylamines.