Development of Catalytic Reactions Using Water as a Solvent.

Abstract

In recent years, organic reactions in aqueous media have attracted much attention, not only because these reactions eliminate the necessity of vigorous drying of solvents and substrates, but also because unique reactivity and selectivity are often observed in the aqueous reactions. Furthermore, organic reactions in water may lead to the development of environmentally friendly chemical processes. We have now developed various types of catalytic organic reactions in aqueous media. Catalytic asymmetric aldol reactions in aqueous media have attained by using rare earth metal triflates and a chiral multi-dentate ligand. Lewis acid catalysis has become feasible in water by using combinations of water-compatible Lewis acidic cations and anionic surfactants. These new catalysts were found to form stable colloidal dispersions and catalyze various reactions in water. Moreover, Brønsted acid- and palladium-catalyzed reactions in water have also been performed with the aid of surfactants.