Heterogeneous Enantioselective Catalysis Using Organic Polymeric Supports

Heterogeneous Enantioselective Catalysis Using Organic Polymeric Supports 

The development of polymer-immobilized ligands and catalysts for asymmetric synthesis is a rapidly growing field [1], which has great importance due mainly to the easy separation and recyclability of polymer-supported catalysts. The polymeric catalysts also represent one of the most powerful tools for green sustainable chemistry, in the sense that they can be easily recovered and reused many times. 

The most common polymer supports used for chiral catalyst immobilization are polystyrene-based crosslinked polymers, although poly(ethylene glycol) (PEG) represents an alternative choice of support. In fact, soluble PEG-supported catalysts show relatively high reactivities (in certain asymmetric reactions) [le] which can on occasion be used in aqueous media [le]. Methacrylates, polyethylene fibers, polymeric monoliths and polynorbornenes have been also utilized as efficient polymer supports for the heterogenization of a variety of homogeneous asymmetric catalysts. 

Handbook of Asymmetric Heterogeneous Catalysis. Edited by K. Ding and Y. Uozumi Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31913-8 

Degni et al. developed a new method for the anchoring of chiral prohnol derivatives, whereby N-(4-vinylbenzyl)-a,a-diphenyl-prolinol was immobihzed on polyethylene fibers by electron beam-induced pre-irradiahon grafting using styrene as a comonomer. The chirally modified polymer fibers 2 were used as a catalyst for the asymmetric ethylation of aldehyde, with moderate enanhoselectivity [3]. 

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I 3 Heterogeneous Enantioselective Catalysis Using Organic Polymeric Supports... 

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