N-Heterocyclic Carbene (NHC) Ligands

ChemFiles 2006, 6.8, 14.

Emerging Class of Privileged Ligands

Product Highlights

• Mediate an incredible breadth of transformations
• Provide robust stability to the metal center
• More active in many reactions than the related phosphine catalysts
• Readily modified to incorporate chirality, immobilization, and H₂O solubility

NHC (N-heterocyclic carbenes) have evolved to become powerful, universal ligands for the rapid synthesis of novel organometallic complexes.¹ In particular, NHC ligands have found practical use when bound to metals that are know to display high catalytic activity in related organophosphane metal coordination chemistry.^2-4 Heterocyclic carbenes are emerging as a privileged class of ligands due to several attractive features including: 1) facile tuning of the electronics and/or sterics of a metal catalyst system; 2) ease of synthetic preparation from conveniently available starting materials; and 3) exhibit strong binding to the metal thus creating a highly productive catalyst. we are pleased to offer a diverse array of NHC ligands that have been successfully applied in reactions ranging from amination⁵ to C–C bond formation⁶ to hydrosilylation.⁷

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References

1. Herrmann W. 2002. Angew. Chem. Int. Ed. Engl. 41, 1290. https://doi.org/10.1002/1521-3773(20020415)41:8%3C1290::AID-ANIE1290%3E3.0.CO;2-Y

2. Herrmann W, et al. 1992. Chem. Ber. 125, 1795.

3. Ofele K, et al. 1993. J. Organomet. Chem. 459, 177.

4. Herrmann W, et al. 1994. J. Organomet. Chem. 480, C7.

5. Stauffer SR, Lee S, Stambuli JP, Hauck SI, Hartwig JF. 2000. High Turnover Number and Rapid, Room-Temperature Amination of Chloroarenes Using Saturated Carbene Ligands. Org. Lett.. 2(10):1423-1426. https://doi.org/10.1021/ol005751k

6. Hadei N, Kantchev EAB, O'Brie CJ, Organ MG. 2005. The First Negishi Cross-Coupling Reaction of Two Alkyl Centers Utilizing a Pd?N-Heterocyclic Carbene (NHC) Catalyst?. Org. Lett.. 7(17):3805-3807. https://doi.org/10.1021/ol0514909

7. Yun J, Kim D, Yun H. 2005. A new alternative to Stryker's reagent in hydrosilylation: synthesis, structure, and reactivity of a well-defined carbene?copper(ii) acetate complex. Chem. Commun..(41):5181. https://doi.org/10.1039/b509964a