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Nickel-NHC Catalysts for the Amination of Aryl Chlorides and Reductive Couplings

New Air Tolerant Versatile Catalysts for C−C and C−N Bond Formation

Nickel-catalysts supported by phosphines, amines, and N-heterocyclic carbenes have been widely used in the development of important C-C and C-heteroatom reactions.[1-4]  In many cases, Ni-NHC complexes were found to facilitate more-efficient transformations and complementary selectivities compared to phosphine and amine-based systems.  Typically, Ni-NHC catalysts were prepared in situ  from Ni(COD)2 and ligand.[4] Unfortunately, however, in situ generation of these catalysts can be problematic due to increased sensitivity of Ni-NHC systems to metal-ligand stoichiometry than those with phosphine or amine ligands.[4-6]  To address this challenge, researchers at the University of Michigan sought to develop a new class of discrete Ni(0) catalysts with pre-defined 1:1 NHC–metal stoichiometry.  Remarkably, stabilization of an electron-rich [Ni-NHC] metal fragment with electron deficient olefins (e.g. methyl methacrylate, di-tert-butyl fumarate) was found to give well-defined, highly active, air-tolerant pre-catalysts of broad utility.[7]

Strem is proud to announce the release of this technology to customers.  As shown in Fig. 1, pre-catalysts featuring IMes 28-1040 and 28-1050 NHC-ligands[7]  are now available for purchase by catalog or website.

                           28-1040       28-1050

Fig. 1.  New, well-defined Ni(0)-NHC catalysts available from Strem.

So far, catalytic activity and efficiency of representative members of (NHC)−Ni(0) catalysts have been evaluated in reductive coupling of aldehydes and alkynes and in N-arylations of amines.  Importantly, however, this class of catalysts are expected to be suitable for a wide array of Ni(0)-catalyzed processes.[7]

 

References:

  1. Nat. Rev. Chem. 2017, 1, 0025.
  2. Nat. Commun. 2016, 7, 11073.
  3. Org. Lett. 2015, 17, 2166.
  4. Inorg. Chim. Acta 2015, 431, 61.
  5. Organometallics 2013, 32, 6265.
  6. Organometallics 2005, 24, 3442.
  7. ACS Catal. 2018, 8, 6606.

 

Products Mentioned & Related Resources:

28-1040: Bis(di-tert-butyl fumarate)(1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene)nickel(0), 96% (2091838-72-9)

28-1050: Bis(methyl methacrylate)(1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene)nickel(0), 98% (2230140-51-7)

NHC Nickel Catalysts

NHC Products

Catalysis Product Families

 

 

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