Synergistic Catalysis by Multifunctionalized Solid Surfaces for Nucleophilic Addition Reactions

This review paper treats with acid-base and Pd-complex-base bifunctional catalyst surfaces used to catalyze nucleophilic addition reactions. A silica-alumina-supported tertiary amine was found to be a highly active heterogeneous catalyst for Michael additions and cyano-ethoxycarbonylation. These reactions barely proceeded with either a homogeneous amine or silica-alumina support, indicating that synergistic catalysis occurred between the silica-alumina surface and basic amine. Silica-alumina, which contains both tertiary and primary amines, was an efficient catalyst for one-pot synthesis of 1,3-dinitroalkanes from aldehydes and nitromethane. The acid-base synergistic catalysis was applied to metal complex-base synergistic catalysis. Both the Pd-complex and tertiary amine-immobilized silica was an excellent heterogeneous catalyst for the Tsuji-Trost reaction. Spectroscopic analyses, such as solid-state MAS NMR, revealed the structures of prepared catalysts, immobilization mechanism of amine groups on the silica-alumina surface, and reaction intermediates and catalytic reaction mechanism. Substrate scope for the cyanation, Michael reaction, 1,3-dinitroalkane synthesis, and the Tsuji-Trost reaction are also described.