Polymer-immobilized chiral catalysts

Abstract

This review illustrates the current strategies and potential of polymer-immobilized chiral catalysts for highly enantioselective asymmetric synthesis. Abstract:Polymer immobilization of chiral catalysts has progressed extensively over the past years. Recent intensive development of chiral organocatalysts resulted in the identification of numerous highly active catalysts, which are, however, still far less effective than transition metal catalysts. Separation of relatively large amounts of organocatalysts from the reaction mixture causes problems during product isolation. In the case of chirally modified metal catalysts, recovery of the valuable metal species and suppression of metal leaching are perpetually important requirements in the design of environmentally friendly chemical processes. Various types of chiral organocatalysts and metal catalysts have been immobilized as pendant groups onto the side chains of polymer supports. Another important polymer immobilization technique is the incorporation of a chiral catalyst into its main chain, with several types of chiral catalyst monomers having been copolymerized with achiral monomers for their production.Recently, the synthesis of chiral main-chain polymeric catalysts has progressed extensively. Moreover, many examples of polymer-immobilized catalysts exhibited higher enantioselectivities in comparison to those of the corresponding low-molecular-weight catalyst. The development of these polymer-immobilized chiral

Development and Scale-up of an Organocatalytic Enantioselective Process to Manufacture (S)-Pregabalin

“…10b-d In this context, it is noteworthy the immobilization of Cinchona derived phase transfer catalysts on polystyrene beads, which could be used to perform an enantioselective step and recycled. 11 Importantly, the reactions carried out with the polystyrene bound catalysts gave similar conversion and enantioselectivity as the one carried out using the unbound agents. Therefore on the bases of cost of reagents, chemical efficiency and precedents for large scale manufactures, Phase Transfer Catalysis (PTC) was selected as the technology of choice for the development of a new process to prepare (S)-1.…”

Preparation of a novel magnetically recoverable copper complex catalyst and its application in the Henry reaction

“…Therefore, the development of reusable complex catalysts is desirable. From the perspective of sustainable technology, the attachment of a homogeneous catalyst to a solid carrier provides many benefits, including easy separation of the catalyst and the product so that the catalyst can be recycled . Fe 3 O 4 magnetic nanomaterials have become good carriers for homogeneous catalysts because they can realize rapid magnetic separation with an external magnetic field.…”

Synthesis of Cinchona Alkaloid Sulfonamide Polymers as Enantioselective Catalysts for the Michael Addition Reaction of β-Ketoester and Nitrostyrene

“…Several types of cinchona derived organocatalysts have been attached to crosslinked polystyrene and applied in asymmetric catalysis ,. Cinchona‐based sulfonamide was also attached to crosslinked polystyrene .…”