Synergistic effect of ultrasound and deep eutectic solvent choline chloride–urea as versatile catalyst for rapid synthesis of β-functionalized ketonic derivatives

Abstract

A green protocol for efficient synthesis of β-functionalized ketonic derivatives is achieved with the combination of ultrasound and the deep eutectic solvent (DES) choline chloride–urea [ChCl:urea (1:2)]. Under optimized conditions, nucleophilic attack of active methylene on α,β-unsaturated ketones gives the conjugate addition product in the short span of 40–50min an excellent yield of 89–95%. The experimental procedure is very simple, easy to set up, solvent free and completely eliminates the use of any toxic metal catalyst. The use of ChCl:urea as a biodegradable, recyclable and reusable catalyst (up to five cycles) further increases the scope of the developed methodology.