Stepwise synthesis and catalysis in C–S cross-coupling of pyridine-functionalized N-heterocyclic carbene nickel(ii) complexes by mechanochemistry

Abstract

The synthesis of three N-heterocyclic carbene complexes by stepwise grinding was described in this paper. The benzimidazolium salts ([H2L]Br2 and [H2L](PF6)2 ([H2L] =1,1’-di(2-picolyl)-3,3’-methylenedibenzoimidazolium) were initially prepared. Their reactions with Ni(OAc)2·4H2O...

Green metrics in mechanochemistry

“…The catalytic response is mediated by a transition metal- N -Heterocyclic carbene (metal-NHC) complex ([NiLBr]PF 6 ) 118 (Scheme 26, eqn (1)). 156 For instance, the [NiLBr]PF 6 complex was readily obtained using a four-step mechanochemical synthesis. The benzimidazole 113 and 2-chloromethylpyridine 114 were first ground in the presence of NaOH and water ( η = 0.01 μL mg −1 ) to produce N -pyridylmethylbenzimidazole 115 (95% yield).…”

Mechanosynthesis of polymeric and binuclear copper complexes via dehydrochlorination and their application in solvent-free C–S bond cross-coupling

“…To date, most of the reported C-S coupling reactions have been conducted in a solution, which generally requires longer reaction times, higher temperatures, and the addition of cocatalysts or an argon-protected atmosphere to accomplish satisfactory results (ESI, † Table S7). Compared to the catalyst pyridine-functionalized carbene nickel complex ([NiLBr]PF 6 ), we recently reported 22 using mechanical methods, 2′-Cu is more advantageous in terms of the catalyst dose (1.0 mol% vs. 1.8 mol%) and reaction time (20 min vs. 30 min) under the same mechanochemical conditions, and produces nearly equivalent yields, which suggests that 2′-Cu mechanically catalyzed C-S coupling reaction is greener and more efficient.…”

“…Recently, we applied pyridine-functionalized heterocyclic carbene nickel( ii ) complexes into the C–S couplings under the optimal mechanochemical conditions, realizing a clean and sustainable system. 22 However, compared to the traditional solution-based strategies, mechanochemistry is still far under explored and offers promising potential in C–S cross-coupling. In this study, the complexes synthesized were further used in the cross-coupling of mechanochemical C–S bonds in order to realize that the entire process from synthesis to catalytic was performed by mechanochemistry.…”

The Application of Dibromohydantoin in Chemical Experiment Pedagogy

“…α-Bromoacetophenone and its derivatives serve as crucial intermediates in organic synthesis, finding extensive applications in the production of functional chemicals like pharmaceuticals and pesticides. − These compounds are primarily obtained through α-site bromination of acetophenone derivatives with various substituents. Presently, the Journal of Chemical Education has documented various bromination reactions encompassing aromatic rings, olefin, and benzyl groups. − However, there is a lack of teaching experiments reporting on the bromination reaction at the α-carbon of carbonyl compounds, primarily due to the absence of safe and environmentally friendly bromination reagents.…”