19222-81-2Relevant articles and documents
A waste-minimized protocol for copper-catalyzed Ullmann-type reaction in a biomass derived furfuryl alcohol/water azeotrope
Ferlin, Francesco,Trombettoni, Valeria,Luciani, Lorenzo,Fusi, Soliver,Piermatti, Oriana,Santoro, Stefano,Vaccaro, Luigi
, p. 1634 - 1639 (2018)
We report the use of biomass-derived furfuryl alcohol as an effective bidentate ligand able to promote the Ullmann-type copper-catalyzed coupling of aryl halides with heteroaromatic or aliphatic amines. Furfuryl alcohol (FA) can be mixed with water to form the corresponding azeotrope (20 wt% of FA) and therefore can be easily recovered and reused. This protocol is efficiently applied to substrates with various electronic nature and affords the expected products (27 examples) in generally good to excellent yields. It has also been demonstrated that the protocol is both chemically and environmentally effective as the azeotropic mixture can be easily and almost quantitatively recovered at the end of the process.
Aryl Amination Using Soluble Weak Base Enabled by a Water-Assisted Mechanism
Lau, Sii Hong,Yu, Peng,Chen, Liye,Madsen-Duggan, Christina B.,Williams, Michael J.,Carrow, Brad P.
supporting information, p. 20030 - 20039 (2021/01/01)
The amination of aryl halides has become one of the most commonly practiced C-N bond-forming reactions in pharmaceutical and laboratory syntheses. The widespread use of strong or poorly soluble inorganic bases for amine activation nevertheless complicates the compatibility of this important reaction class with sensitive substrates as well as applications in flow and automated synthesis, to name a few. We report a palladium-catalyzed C-N coupling using Et3N as a weak, soluble base, which allows a broad substrate scope that includes bromo- and chloro(hetero)arenes, primary anilines, secondary amines, and amide type nucleophiles together with tolerance for a range of base-sensitive functional groups. Mechanistic data have established a unique pathway for these reactions in which water serves multiple beneficial roles. In particular, ionization of a neutral catalytic intermediate via halide displacement by H2O generates, after proton loss, a coordinatively unsaturated Pd-OH species that can bind amine substrate triggering intramolecular N-H heterolysis. This water-assisted pathway operates efficiently with even weak terminal bases, such as Et3N. The use of a simple, commercially available ligand, PAd3, is key to this water-assisted mechanism by promoting coordinative unsaturation in catalytic intermediates responsible for the heterolytic activation of strong element-hydrogen bonds, which enables broad compatibility of carbon-heteroatom cross-coupling reactions with sensitive substrates and functionality.
Copper/β-diketone-catalysed N-arylation of carbazoles
Chen, Fei,Liu, Ning,Ji, Enhui,Dai, Bin
, p. 51512 - 51523 (2015/06/25)
A copper-catalysed C-N bond-forming reaction of carbazoles with aryl iodides is described. Several commercially available ligands such as β-diketone and diamine, are tested in the N-arylation of carbazoles. The catalytic system generated in situ from an inexpensive copper salt, simple β-diketone and inorganic base efficiently N-arylated the carbazoles. A wide range of aryl iodides and carbazoles can be coupled to generate N-arylcarbazoles in the presence of various functional groups. However, the sterically hindered effect of aryl iodides is evident in this catalytic system. The selectivity of two iodine atoms on the aromatic ring of diiodobenzene is evaluated in the developed catalytic system. Results showed that the selectivity of diiodobenzene can be tuned by the reaction temperature.
