Highly selective conjugate additions of Grignard reagents to cyclic and linear enones catalyzed by recyclable heterogeneous polysaccharide/nanocopper catalysts are disclosed. The method also allows the synthesis of ketones with an all-carbon quaternary center. When integrated with catalytic asymmetric tandem reactions using enals and β-ketoesters, it yields chiral β,δ-disubstituted ketones with high stereoselectivity.