Reactivity of [K₃(phen)₈][Cu(NPh₂)₂]₃—a possible intermediate in the copper(i)-catalyzed N-arylation of N-phenylaniline

Abstract

Complex [K3(phen)8][Cu(NPh2)2]3 (1, phen = phenanthroline) was isolated from the catalytic C-N cross coupling reaction based on the CuI-phen-tBuOK catalytic system. Complex 1 can react with 4-iodotoluene to give 4-methyl-N,N-diphenylaniline (3a) in 50% yield (based on all available NPh2(-) ligands of complex 1). In addition, 1 can also work as an effective catalyst for the C-N coupling reactions under the same reaction conditions, indicating that 1 may be an effective intermediate of the catalytic system. In the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), a radical scavenger, the stoichiometric reaction between complex 1 and 4-iodotoluene was significantly quenched to give a low yield of 12%. The results suggest that the radical path dominates in the reaction, with (phen)KNPh2 as the possible radical source. The structures of 1 and (phen)KNPh2 were both determined by single crystal X-ray diffraction studies.

A Heteroarylamine Library: Indium‐Catalyzed Nucleophilic Aromatic Substitution of Alkoxyheteroarenes with Amines

“…Since a biphenyl structure sandwiched by two diarylamino groups has been attracting considerable attention as charge transport materials found in, for instance, organic light‐emitting diodes and photovoltaic cells, a heteroarylamine in hand was applied to construct such a related architecture but designed uniquely. Amongst a lot of candidates, we picked up 3 uf , which was then treated with 4,4′‐diiodobiphenyl ( 10 ) under the Ullmann−Goldberg conditions, thereby giving potentially useful structure 11 . It was found that 11 is a blue‐violet light‐emitting photoactive molecule with the emission maximum at 407 nm when excited at 265 nm in CH 2 Cl 2 (Scheme ).…”

Synthesis, Characterisation and Reactivity of Copper(I) Amide Complexes and Studies on Their Role in the Modified Ullmann Amination Reaction

“…An umber of different ligand systems have been reported for accelerating the modified Ullmann reaction, with perhaps one of the most studied being 1,10-phenanthroline (phen). Phen has been shown to significantly improvet he yields and reaction rates in the arylation of arylamines, [4][5][6][7][8][9] hydrazines [71] and aliphatic alcohols. [72,73] However,s tudies employing this ligand in alkylamine-aryl coupling reactions are less well documented, with diketone and amino acid based ligandsm ore often employed.…”

“…The effect of phen on the reactivity of 3 was more pronounced when [D 6 ]DMSO was used as the solvent, with the yield unexpectedly decreasing from 75 %t o2 6%.T he yields obtained with complexes 4 and 5 on addition of phen were also diminished in [D 6 ]DMSO compared to their ligand-free analogues.T hese resultsa re somewhat surprising in light of the prominentr ole played by phen in copper-catalysed Ullmann amination. [4][5][6][7][8][9] Nevertheless, they can be explained in the context of the solution studies which showedt he favoured formation of the ionic cuprate species (III,S cheme 4) on addition of phen to copper(I) amide in DMSO.P revious studies on the reactivity of isolatedb isamidocuprate complexes [Cu(NR 2 ) 2 ] À (NR 2 = NPh 2 ; [30] phthalimidate [29] )h ave shown these anionic speciestohave little or no reactivity in the cross-coupling reaction with aryl halides. If, as seems likely,t he bis(dialkylamino)cupratec omplexes present in the reactionm ixture here also exhibit low reactivity,t his could help explain the observed reductioni np roduct yield.…”

“…[1] However,t his classical methodf or crosscoupling aryl halidesa nd amines has many drawbacks including high (stoichiometric) copper metal loadings, highr eaction temperatures anda lso long reaction times. [2,3] More recently new protocols that incorporate the use of bidentate ligands such as 1,10-phenanthroline (phen) [4][5][6][7][8][9] have enabled these re-actions to be carried out at lower reaction temperatures ( 110 8C) with lower copper loadings ( 10 %). [10][11][12][13] This improvedc opper-catalysed reactioni sc ommonly referred to as the modified Ullmann amination reaction (Scheme 1).…”

Novel Turtle‐Shape Dendrimers Based on a Pyrene Core

“…The synthesis of the second dendron: N,N ‐di(4‐tolyl)‐4’‐iodophenylamine (12) was also achieved in a straightforward manner. A ready available di‐tolylamine 9 was coupled with iodobenzene 10 using a modified Ullmann protocol . The substituted triphenylamine derivative 11 obtained in this way was subjected to an aromatic iodination procedure to afford 12 in good yield (Scheme ) …”