Mechanochemical Michael reactions of chalcones and azachalcones with ethyl acetoacetate catalyzed by K2CO3 under solvent-free conditions

Michael addition reactions of chalcones and azachalcones with ethyl acetoacetate have been successfully performed in the presence of catalytic amount of K2CO3 (10 mol %) and under the high-speed vibration milling conditions. The reactions take place at ambient temperature without any solvent and full completion can be achieved in very short time (20-40 min). In most cases, conventional side reactions were avoided and thus high chemoselectivity and quantitative yields were achieved. The desired Michael adducts were exclusively obtained consisting of two diastereoisomers anti and syn, which were determined and assigned by H-1 NMR spectroscopy.