Copper-Catalyzed Direct Aryl Quaternization of N-Substituted Imidazoles to Form Imidazolium Salts
摘要:
Diaryliodonium salts are employed to directly quaternize N-substituted imidazoles by using a copper catalyst to construct aryl imidazolium salts in moderate to excellent yields. This transformation is tolerant to a broad range of functional groups and provides a straightforward, efficient, and versatile route to synthesize aryl imidazolium as well as triazolium salts, especially the unsymmetric version.
A silica sulfuric acid-catalyzed three-component one-pot synthesis of 1,3-diarylimidazolium tetrafluoroborates was undertaken via the reaction of aromatic amine, formaldehyde and glyoxal at room temperature in ionic liquid [BMIM][BF4] with good yields. Up to four new bonds and one new ring were formed in one-pot with water as the only by-product in the reactions. The product 4d was determined by X-ray diffraction. This work develops an efficient and low-cost preparation of 1,3-diarylimidazolium and N-heterocylic carbene.
Azaborines: synthesis and use in the generation of stabilized boron-substituted carbocations
作者:J. J. Clarke、P. Eisenberger、S. S. Piotrkowski、C. M. Crudden
DOI:10.1039/c7dt01329a
日期:——
A formal N-heterocyclic carbene insertion into the B–H bond of 9-BBN followed by a ring expansion reaction is reported. NHC-9-BBN adducts were reacted in one or two steps to give the corresponding di- or triazaborines. Hydride abstraction of selected species with [Ph3C]+ is facile, giving rise to 6π-aromatic cations with Lewis acidity comparable to Lewis acids commonly employed in frustrated Lewis
Diaryliodonium salts are employed to directly quaternize N-substituted imidazoles by using a copper catalyst to construct aryl imidazolium salts in moderate to excellent yields. This transformation is tolerant to a broad range of functional groups and provides a straightforward, efficient, and versatile route to synthesize aryl imidazolium as well as triazolium salts, especially the unsymmetric version.