Polymer-Supported Chiral Organocatalysts: Synthetic Strategies for the Road Towards Affordable Polymeric Immobilization

• Published in: European Journal of Organic Chemistry Vol. 2010; no. 17; pp. 3179 - 3204
• Main Authors: Kristensen, Tor E., Hansen, Tore
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-06-2010; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: Asymmetric catalysis; Asymmetric synthesis; Biomimetic synthesis; Catalysis; Catalysts: preparations and properties; Chemistry; Exact sciences and technology; General and physical chemistry; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Immobili­zation; Organic chemistry; Organocatalysis; Preparations and properties; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Imidazole derivatives; Organic cation; Iminium compounds; Nitrogen heterocycle; Enamine; Biomimetic synthesis; Immobilization; Polymer; Chiral compound; Polyaminoacid; Asymmetric catalysis; Organocatalysis; Styrene derivative polymer; Asymmetric synthesis; Biomimetic compound; Aminoacid; Polarity; Acrylic polymer; Copolymer; Chemical synthesis; Solvent; Catalyst
• DOI: 10.1002/ejoc.201000319
• EISSN: 1099-0690
• ISSN: 1434-193X

In this microreview, we highlight the field of polymer‐supported organocatalysis, especially immobilized enamine and iminium organocatalysts. We try to formalize the overall synthetic strategies for polymeric immobilization as spanning the area of two overlapping regions, from a copolymer strategy favoured by low‐valued and small catalysts to a classical post‐modification strategy favoured by valuable and/or large catalysts. Organocatalysis is particularly interesting as it is probably best described as being located in the transitional region, and we will trace the historic and factual origins for the unfortunate predispositions towards post‐modification schemes. In addition, we try to identify affordable and useful syntheses of key organocatalyst immobilization intermediates, as well as polymer supports that are more compatible with a broader range of reaction solvent polarity, something of crucial importance in organocatalysis.
The preparation and utilization of enamine and iminium organocatalysts have seen a tremendous growth during the last decade. In this microreview, we highlight the polymer‐supported versions of these catalysts, with a special focus on the synthetic strategies that have been undertaken to prepare them and analyze these strategies in a historical context.