62154-64-7Relevant academic research and scientific papers
Synthesis of a series of pyridine-functionalised benzoimidazole-based N-heterocyclic carbene ligands
Guo, Jin,He, Pan,Yang, Long,Liu, Xiang,Lv, Lanlan,Shi, Yanhui,Cao, Changsheng
, p. 111 - 113 (2012)
A series of pyridine-functionalised bis(benzoimidazolium) dichlorides, dibromides and dihexafluorophosphate with different alkyl bridged length (n = 2-4) were synthesised in high yield. All the compounds are new and fully characterised by 1H and 13C NMR, IR and elemental analyses.
Hemilability-Driven Water Activation: A NiII Catalyst for Base-Free Hydration of Nitriles to Amides
Singh, Kuldeep,Sarbajna, Abir,Dutta, Indranil,Pandey, Pragati,Bera, Jitendra K.
, p. 7761 - 7771 (2017/06/06)
The NiII complex 1 containing pyridyl- and hydroxy-functionalized N-heterocyclic carbenes (NHCs) is synthesized and its catalytic utility for the selective nitrile hydration to the corresponding amide under base-free conditions is evaluated. The title compound exploits a hemilabile pyridyl unit to interact with a catalytically relevant water molecule through hydrogen-bonding and promotes a nucleophilic water attack to the nitrile. A wide variety of nitriles is hydrated to the corresponding amides including the pharmaceutical drugs rufinamide, Rifater, and piracetam. Synthetically challenging α-hydroxyamides are accessed from cyanohydrins under neutral conditions. Related catalysts that lack the pyridyl unit (i.e., compounds 2 and 4) are not active whereas those containing both the pyridyl and the hydroxy or only the pyridyl pendant (i.e., compounds 1 and 3) show substantial activity. The linkage isomer 1′ where the hydroxy group is bound to the metal instead of the pyridyl group was isolated under different crystallization conditions insinuating a ligand hemilabile behavior. Additional pKa measurements reveal an accessible pyridyl unit under the catalytic conditions. Kinetic studies support a ligand-promoted nucleophilic water addition to a metal-bound nitrile group. This work reports a Ni-based catalyst that exhibits functional hemilability for hydration chemistry.
