Mannich reaction in Brönsted acidic ionic liquid: A facile synthesis of β-amino carbonyl compounds

Brönsted acidic ionic liquid containing nucleophile 1-methylimidazole and triphenylphosphine with 1,4-butane sultone and inorganic anions p-toluenesulfonic acid (PTSA) and trifluoroacetic acid (TFA) catalyzed Mannich reaction smoothly to afford β-amino carbonyl compounds in excellent yield and less time. Effect of addition of two drops of water on the product yield and effect of anions and cations of the ionic liquid on the reaction rate have been investigated. The ionic liquid was easily separated from the reaction mixture by water extraction and was recycled four times without any loss in activity.

Graphical abstractAn efficient process for a simple and fast reaction of different aldehydes, ketones and amines (Mannich reaction) to afford corresponding β-amino carbonyl compounds is demonstrated. The reaction proceeded very fast with high yield of the desired Mannich base using catalytic amount of ionic liquid. Figure optionsDownload full-size imageDownload as PowerPoint slide