Silver N-heterocyclic carbenes: emerging powerful catalysts

The requirements of better biocompatibility, lower loading, and greater economy for catalysts have placed increasing interest in silver N-heterocyclic carbenes (Ag–NHCs) as catalysts in organic synthesis. A recent strategy of using Ag-NHC in the reaction system to prepare other metal-NHC catalysts greatly simplifies the application of other metal-NHC catalysts in organic synthesis. As strong σ donors, NHCs combine with silver to make monovalent or high-valent silver species more stable, which can not only prevent side reactions, but also facilitate reactions that involve high-valent silver intermediates. Ag-NHC complexes have begun to be explored as chiral catalysts for asymmetric reactions, which will promote the wide application of silver catalysts in asymmetric synthesis. The development of supported Ag-NHCs can greatly reduce the amount of silver catalyst in the reaction system, and can make the silver catalyst recyclable. Silver N-heterocyclic carbenes (Ag–NHCs) exhibit good biocompatibility and have found a wide range of applications in medicine and coordination chemistry. However, due to the strong σ donor nature of NHC, its coordination with silver can weaken the Lewis acidity of Ag(I), leading to slow development of Ag-NHCs in the field of catalysis. Here, we systematically review the application of Ag-NHCs as catalysts in organic synthesis and clearly elaborate the reasons for the slow development of Ag-NHCs in the field of catalysis along with future development opportunities for such complexes as catalysts. Silver N-heterocyclic carbenes (Ag–NHCs) exhibit good biocompatibility and have found a wide range of applications in medicine and coordination chemistry. However, due to the strong σ donor nature of NHC, its coordination with silver can weaken the Lewis acidity of Ag(I), leading to slow development of Ag-NHCs in the field of catalysis. Here, we systematically review the application of Ag-NHCs as catalysts in organic synthesis and clearly elaborate the reasons for the slow development of Ag-NHCs in the field of catalysis along with future development opportunities for such complexes as catalysts. a three-component reaction using amine, aldehyde, and alkyne as raw materials. a substance capable of forming a covalent bond with a base by accepting a pair of electrons from it. a reaction in which two compounds exchange components to produce two other compounds. a class of compounds in which the carbene is located on an N-heterocyclic scaffold. a catalyst and the cocatalyst are uniformly dispersed, and they are supported on a specially selected carrier. the reaction of ligand transfer from one metal to another.