Halo-Bridged Abnormal NHC Palladium(II) Dimer for Catalytic Dehydrogenative Cross-Coupling Reactions of Heteroarenes

This work describes the dehydrogenative coupling of heteroarenes using a dimeric halo-bridged palladium­(II) catalyst bearing an abnormal NHC (<i>a</i>NHC) backbone. The catalyst can successfully activate the C–H bond of a wide range of heteroarenes, which include benzothiazole, benzoxazole, thiophene, furan, and <i>N</i>-methylbenzimidazole. Further, it exhibited good activity for heteroarenes bearing various functional groups such as CN, CHO, Me, OMe, OAc, and Cl. Additionally, we isolated the active catalyst by performing stoichiometric reaction and characterized it as the acetato-bridged dimer of (<i>a</i>NHC)­PdOAc by single-crystal X-ray study

Halo-Bridged Abnormal NHC Palladium(II) Dimer for Catalytic Dehydrogenative Cross-Coupling Reactions of Heteroarenes

This work describes the dehydrogenative coupling of heteroarenes using a dimeric halo-bridged palladium­(II) catalyst bearing an abnormal NHC (<i>a</i>NHC) backbone. The catalyst can successfully activate the C–H bond of a wide range of heteroarenes, which include benzothiazole, benzoxazole, thiophene, furan, and <i>N</i>-methylbenzimidazole. Further, it exhibited good activity for heteroarenes bearing various functional groups such as CN, CHO, Me, OMe, OAc, and Cl. Additionally, we isolated the active catalyst by performing stoichiometric reaction and characterized it as the acetato-bridged dimer of (<i>a</i>NHC)­PdOAc by single-crystal X-ray study

Integrating Organic Lewis Acid and Redox Catalysis: The Phenalenyl Cation in Dual Role

In recent years, merging different types of catalysis in a single pot has drawn considerable attention and these catalytic processes have mainly relied upon metals. However, development of a completely metal free approach integrating organic redox and organic Lewis acidic property into a single system has been missing in the current literature. This study establishes that a redox active phenalenyl cation can activate one of the substrates by single electron transfer process while the same can activate the other substrate by a donor–acceptor type interaction using its Lewis acidity. This approach has successfully achieved light and metal-free catalytic C–H functionalization of unactivated arenes at ambient temperature (39 entries, including core moiety of a top-selling molecule boscalid), an economically attractive alternative to the rare metal-based multicatalysts process. A tandem approach involving trapping of reaction intermediates, spectroscopy along with density functional theory calculations unravels the dual role of phenalenyl cation

Abnormal-NHC-Supported Nickel Catalysts for Hydroheteroarylation of Vinylarenes

Herein we report the hydroheteroarylation of vinylarenes with benzoxazole in the presence of a free abnormal N-heterocyclic carbene and Ni­(COD)₂, resulting in 1,1-diarylethane products exclusively. In an attempt to understand the mechanism of this catalytic reaction, two abnormal-NHC (<i>a</i>NHC)-coordinated Ni­(II) cyclooctenyl complexes were isolated and their solid-state structures were determined by X-ray crystallographic studies. These Ni­(II) cyclooctenyl complexes act as active catalyst precursors to generate in situ <i>a</i>NHC-Ni­(0) species, which undergo oxidative addition with heteroarene to form Ni­(II) hydride intermediates

Abnormal-NHC-Supported Nickel Catalysts for Hydroheteroarylation of Vinylarenes

Herein we report the hydroheteroarylation of vinylarenes with benzoxazole in the presence of a free abnormal N-heterocyclic carbene and Ni­(COD)₂, resulting in 1,1-diarylethane products exclusively. In an attempt to understand the mechanism of this catalytic reaction, two abnormal-NHC (<i>a</i>NHC)-coordinated Ni­(II) cyclooctenyl complexes were isolated and their solid-state structures were determined by X-ray crystallographic studies. These Ni­(II) cyclooctenyl complexes act as active catalyst precursors to generate in situ <i>a</i>NHC-Ni­(0) species, which undergo oxidative addition with heteroarene to form Ni­(II) hydride intermediates

Abnormal-NHC-Supported Nickel Catalysts for Hydroheteroarylation of Vinylarenes

Herein we report the hydroheteroarylation of vinylarenes with benzoxazole in the presence of a free abnormal N-heterocyclic carbene and Ni­(COD)₂, resulting in 1,1-diarylethane products exclusively. In an attempt to understand the mechanism of this catalytic reaction, two abnormal-NHC (<i>a</i>NHC)-coordinated Ni­(II) cyclooctenyl complexes were isolated and their solid-state structures were determined by X-ray crystallographic studies. These Ni­(II) cyclooctenyl complexes act as active catalyst precursors to generate in situ <i>a</i>NHC-Ni­(0) species, which undergo oxidative addition with heteroarene to form Ni­(II) hydride intermediates