Journal ArticleDOI
Organocatalysis by N-Heterocyclic Carbenes
TLDR
The inversion of the classical reactivity (Umpolung) opens up new synthetic pathways in biochemical processes as nucleophilic acylations and in nature, the coenzyme thiamine (vitamin B1), a natural thiazolium salt, utilizes a catalytic variant of this concept in biochemical process as nucleophile acylation.Abstract:
In the investigation of efficient chemical transformations, the carbon-carbon bond-forming reactions play an outstanding role. In this context, organocatalytic processes have achieved considerable attention. 1 Beside their facile reaction course, selectivity, and environmental friendliness, new synthetic strategies are made possible. Particularly, the inversion of the classical reactivity (Umpolung) opens up new synthetic pathways. 2 In nature, the coenzyme thiamine (vitamin B1), a natural thiazolium salt, utilizes a catalytic variant of this concept in biochemical processes as nucleophilic acylations. 3 The catalytically active species is a nucleophilic carbene. 4read more
Citations
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An overview of N-heterocyclic carbenes
TL;DR: A concise overview of N-heterocyclic carbenes in modern chemistry is provided, summarizing their general properties and uses and highlighting how these features are being exploited in a selection of pioneering recent studies.
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N-Heterocyclic Carbenes in Late Transition Metal Catalysis
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Heterocyclic Carbenes: Synthesis and Coordination Chemistry
TL;DR: New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclized isocyanides have been developed recently.
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Organocatalytic Reactions Enabled by N-Heterocyclic Carbenes.
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Organocatalytic cascade reactions as a new tool in total synthesis
TL;DR: The first applications of asymmetric organocatalytic cascade reactions to the total synthesis of natural products are presented, paving the way for a new and powerful strategy that can help to address these issues.
References
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A stable crystalline carbene
TL;DR: Synthese, structure et caracterisation du (1,3-bis [1-adamantyl]-2, 3-dihydro)-2,carbenoimidazole prepare par deprotonation du chlorure de (1 3-bis] [1]- imidazolium as discussed by the authors.
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Polymeric Systems for Controlled Drug Release
TL;DR: Kevin Shakesheff investigates new methods of engineering polymer surfaces and the application of these engineered materials in drug delivery and tissue engineering.
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Electronic stabilization of nucleophilic carbenes
TL;DR: In this paper, the remarkable ability of the imidazole nucleus to stabilize a carbene center at the C-2 position is demonstrated by the isolation of 1,3,4,5-tetramethylimidazol-2-ylidene.
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Methods of Reactivity Umpolung
TL;DR: There are six principal methods of umpolung: 1 2n-oxidation, heteroatom exchange and modification, homologation and its reversal, the cyclopropane “trick”, use of acetylenes, and redox reactions; under certain circumstances none of these techniques is necessary in cases where direct umpoline is possible.