Ultrasound-assisted aza-Michael reaction in water: A green procedure

The conjugate addition of amines to conjugated alkenes (commonly known as aza-Michael reaction) constitutes a key step for the synthesis of various complex natural products, antibiotics, α-amino alcohols and chiral auxiliaries. Ultrasound-induced addition of several amines to α, β-unsaturated ketones, esters and nitriles has been carried out very efficiently in water as well as under solvent-free conditions. No catalysts or solid supports have been used in this method. Remarkable enhancement of reaction rate has been observed in water under ultrasound-induced method. This environmentally benign procedure has provided clean formation of the products with better selectivity.

Ultrasound-induced, environmentally benign aza-Michael addition of several amines to α, β- unsaturated ketones, esters and nitriles has been carried out. The effects of solvents and various conditions have been studied in detail.Figure optionsDownload as PowerPoint slideHighlights
► Ultrasound irradiation accelerates aza-Michael reaction abruptly in water.
► No catalysts or solid supports have been used in this method.
► Reaction of amines to α, β-unsaturated ketones, esters and nitriles is described.
► The effect of different solvents under ultrasound irradiation has been studied.
► All the reactions have allowed the preparation of products in excellent yield.