15408-60-3Relevant academic research and scientific papers
Buttressing Effect as a Key Design Principle towards Highly Efficient Palladium/N-Heterocyclic Carbene Buchwald–Hartwig Amination Catalysts
Zhang, Yin,Lavigne, Guy,Lugan, No?l,César, Vincent
, p. 13792 - 13801 (2017)
The backbone substitution of the standard 1,3-bis(2,6-diisopropylphenyl)-2H-imidazol-2-ylidene (IPr) ligand by dimethylamino groups was previously shown to induce a dramatic improvement in the catalytic efficiency of the corresponding Pd–PEPPSI (pyridine-enhanced pre-catalyst preparation, stabilization, and initiation) pre-catalysts in N-arylation reactions. Herein, a thorough structure/activity study towards rationalizing this beneficial effect has been described. In addition to the previously reported IPr (Formula presented.) and IPr (Formula presented.) ligands, the new IPr (Formula presented.) and IPr (Formula presented.) ligands, which bear one bulkier diisopropylamino group and a combination of dimethylamino and chloro substituents, respectively, have been designed and analyzed in the study. The influence of the backbone substitution was found to be steric in origin and is related to the well-known buttressing effect encountered in arene chemistry. The usefulness and versatility of this approach was demonstrated through the development of a highly efficient catalytic system for the challenging arylation of bulky α,α,α-trisubstituted primary amines. The optimized system based on the [PdCl(η3-cinnamyl)(IPr (Formula presented.))] or [PdCl(η3-cinnamyl)(IPr (Formula presented.))] pre-catalysts operates under unprecedented mild conditions (catalyst loadings: 0.5–2 mol %, reaction temperatures: 40–60 °C) with a wide substrate scope.
Direct Aryl C?H Amination with Primary Amines Using Organic Photoredox Catalysis
Margrey, Kaila A.,Levens, Alison,Nicewicz, David A.
supporting information, p. 15644 - 15648 (2017/11/20)
The direct catalytic C?H amination of arenes is a powerful synthetic strategy with useful applications in pharmaceuticals, agrochemicals, and materials chemistry. Despite the advances in catalytic C?H functionalization, the use of aliphatic amine coupling partners is limited. Described herein is the construction of C?N bonds, using primary amines, by direct C?H functionalization with an acridinium photoredox catalyst under an aerobic atmosphere. A wide variety of primary amines, including amino acids and more complex amines are competent coupling partners. Various electron-rich aromatics and heteroaromatics are useful scaffolds in this reaction, as are complex, biologically active arenes. We also describe the ability to functionalize arenes that are not oxidized by an acridinium catalyst, such as benzene and toluene, thus supporting a reactive amine cation radical intermediate.
