Molecules 2016, 21(8), 1100; https://doi.org/10.3390/molecules21081100
Self-Supported N-Heterocyclic Carbenes and Their Use as Organocatalysts
Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
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Author to whom correspondence should be addressed.
Academic Editor: Maurizio Benaglia
Received: 19 July 2016 / Revised: 13 August 2016 / Accepted: 15 August 2016 / Published: 20 August 2016
(This article belongs to the Special Issue Recent Advancements in Polymer-Supported Catalysis)
Abstract
The study of N-heterocyclic carbenes (NHCs) as organocatalysts has proliferated in recent years, and they have been found to be useful in a variety of reactions. In an attempt to further expand their utility and to study their recyclability, we designed and synthesized a series of self-supported NHCs in which the catalytic carbene groups form part of a densely functionalized polymer backbone, and studied them as organocatalysts. Of the self-Supported NHCs examined, a benzimidazole derived polymer with flexible linkers connecting the catalytic groups was found to be the most efficient organocatalyst in a model benzoin condensation reaction, and thus it was used in a variety of such reactions, including some involving catalyst recycling. Furthermore, it was also used to catalyze a set of redox esterification reactions involving conjugated unsaturated aldehydes. In all of these reactions the catalyst afforded good yield of the desired product and its polymeric nature facilitated product purification. View Full-TextKeywords:
self-supported catalyst; organocatalyst; N-heterocyclic carbene; benzoin condensation; redox esterification
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Ma, S.; Toy, P.H. Self-Supported N-Heterocyclic Carbenes and Their Use as Organocatalysts. Molecules 2016, 21, 1100.
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