Chapter 10: Hydroxyproline Derivatives as Asymmetric Organocatalysts

Useful applications of 4-hydroxyproline-derived amino acids and amino amides bearing ether, ester, sulfonyloxy, carbamoyloxy or some other functional groups at position four of the pyrrolidine ring are reviewed as organocatalysts for asymmetric reactions of organic compounds, including aldol reactions, Mannich reactions, Michael additions, aldehyde α-aminations, and some multicomponent or cascade reactions under homogeneous or heterogeneous conditions. Particular attention is paid to important, from the green chemistry viewpoint, recyclable catalysts bearing polymeric, dendritic or ionic fragments covalently attached to the pyrrolidine ring and to catalytic reactions in heterogeneous reagents/water systems that may find applications in green chemistry and technology.