Imidazole-Based N-Heterocyclic Carbene (NHC) Ligand Kit
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1.1 Background & Core Advantages of Imidazole NHC Ligands
In 1991, American chemist Anthony J. Arduengo achieved the first stable isolation of free imidazole-type N-heterocyclic carbenes (NHCs), overturning the conventional view that carbenes only exist as transient reactive intermediates[1].
Imidazole NHC ligands possess four prominent merits: strong σ-donating capacity, weak π-accepting character, facile backbone derivatization, and outstanding stability of coordination bonds formed with transition metals. They rapidly complement classic phosphine ligands and have become core ligand skeletons for homogeneous transition metal catalysis, organometallic functional materials, and organocatalysis.
Common imidazolium salt precursors include acenaphtho-fused benzimidazoles, alkyl-substituted unsaturated imidazoles, halogen-modified cyclic imidazoles, and saturated imidazolines. Introducing bulky alkyl side chains such as ethyl, isopropyl, and n-propyl at the ortho positions of N-linked aromatic rings creates a steric shielding cage, which effectively suppresses intermolecular dimerization and deactivation of metal catalytic centers, and greatly improves the thermal stability of metal complexes at high temperatures.
This series of imidazole NHC ligands covers extremely versatile application scenarios:
- Industrial fine chemical production: Pd/Ni-catalyzed Suzuki-Miyaura coupling, Buchwald-Hartwig amination and other C–C / C–N bond formation reactions;
- Noble metal catalysis (Au, Ag, Cu): cyclization and functionalization of alkenes and alkynes;
- Organocatalysis: after base deprotonation, NHCs enable umpolung of aldehydes, catalyzing benzoin condensation, Stetter reaction, etc.;
- Olefin polymerization catalysis via coordination with transition metals;
- Stabilizer for coating noble metal nanoparticles;
- CO₂ activation and cycloaddition for carbonate synthesis, supporting functional material fabrication and carbon resource recycling.
These cost-effective carbene ligands are suitable for both high-throughput catalytic screening in laboratories and scaled-up industrial process optimization[2-5].
1.2 Product Launch: Imidazole NHC Ligand Kit
To facilitate academic and industrial research, we launch an imidazole N-heterocyclic carbene ligand kit containing 10 high-performance skeletons, all validated to deliver exceptional catalytic activity and selectivity in numerous organic transformations. Representative applications are listed below:
- Acenaphthoimidazolium precursor (CAS: 2134656-02-1)
Serves as precursor to air- and moisture-stable Pd-PEPPSI-IPentAn palladium precatalysts. Enables efficient Suzuki-Miyaura coupling of sterically hindered tetra-ortho-substituted biaryls, hetero-biaryls and polycyclic aromatics under ambient air[6]; also mediates high-yield Buchwald-Hartwig C–N coupling between sterically encumbered aryl chlorides, sulfur-containing heteroaryl chlorides and aliphatic/aromatic amines[7].
- Acenaphthoimidazolium precursor (CAS: 2540595-72-8)
Derived palladium precatalysts promote direct C–H arylation of heteroarenes including thiophenes, indoles and furans with aryl bromides[8].
- Acenaphthoimidazolium precursor (CAS: 1246183-55-0)
Nickel catalysts built from this precursor realize two transformations:
- C–N amination coupling of sterically hindered and heteroaryl tosylates with primary/secondary amines[9];
- Reductive coupling of alkynes and imines to access polysubstituted allylic amines with high efficiency[10].
- Dual acenaphthoimidazolium precursors (CAS: 1246183-55-0; 1286737-75-4)
Palladium catalysts prepared from the two precursors mediate a tandem dehydrogenation-coupling-aromatization reaction of cyclohexanols and primary alcohols. The reaction generates clean H₂ and H₂O as sole byproducts, selectively delivering ortho-mono- and ortho-disubstituted phenols[11].
- Electron-rich NHC ligand IPrMe (CAS: 916480-65-4)
Zero-valent nickel catalytic system coordinated with IPrMe activates C–O bonds of silyloxyarenes, achieving amination with diverse primary/secondary amines to synthesize anilines[12].
- NHC ligand (CAS: 905931-87-5) paired with nickel
Combined with triisopropylsilane reductant, this Ni/NHC system catalyzes highly exo-selective reductive macrocyclization of alkynals to construct 10–21 membered macrocycles with exocyclic methylene groups (exo/endo regioselectivity >95:5)[13].
- Bulky NHC IHept (CAS: 1157867-61-2) copper complex
Constructs efficient copper hydride catalytic system to mediate 1,3-halogen migration / aryl borylation of 2-halostyrenes with pinacolborane[14].
1.3 Commercial Supply Notice
Kaitailai Platinum (Anhui) Co., Ltd. officially releases the imidazole-based N-heterocyclic carbene ligand kit. Custom synthesis service for novel imidazolium salt precursors and free NHC ligands is available for global academic institutes and industrial R&D departments. Worldwide inquiries and research cooperation are warmly welcomed.
References
[1] A. J. Arduengo, R. L. Harlow, M. Kline, J. Am. Chem. Soc. 1991, 113, 361.
[2] S. S. Bera, G. Utecht-Jarzyńska, S. Yang, S. P. Nolan, M. Szostak, Chem. Rev. 2025, 125, 5349.
[3] M. Zhong, M. Yuan, RSC Adv. 2025, 15, 15052.
[4] S. Burnett, S. Miller, F. Murphy, C. E. Weetman, ACS Catal. 2026, 16, 5276.
[5] Y. Kong, Chemistry Bulletin 2020, 83, 792.
[6] D.-D. Lu, X.-X. He, F.-S. Liu, J. Org. Chem. 2017, 82, 10898.
[7] F.-D. Huang, C. Xu, D.-D. Lu, D.-S. Shen, T. Li, F.-S. Liu, J. Org. Chem. 2018, 83, 9144.
[8] A. Kumar, M. Kumar, A. K. Verma, J. Org. Chem. 2020, 85, 13983.
[9] J. Jiang, H. Zhu, Y. Shen, T. Tu, Org. Chem. Front. 2014, 1, 1172.
[10] W.-W. Yao, R. Li, J.-F. Li, J. Sun, M. Ye, Green Chem. 2019, 21, 2240.
[11] G. Zeng, L. Shen, Q. Zheng, T. Tu, ACS Catal. 2023, 13, 6222.
[12] E. M. Wiensch, J. Montgomery, Angew. Chem. Int. Ed. 2018, 57, 11045.
[13] H. Wang, S. Negretti, A. R. Knauff, J. Montgomery, Org. Lett. 2015, 17, 1493.
[14] S. C. Schmid, R. V. Hoveln, J. W. Rigoli, J. M. Schomaker, Organometallics 2015, 34, 4164.