N‐Heterocyclic Benzhydrylamines as New N,N‐Bidentate Ligands in Palladium Complexes: Synthesis, Characterization and Catalytic Activity

Abstract

The synthesis of new N,N‐bidentate ligands based on a π‐deficient N‐heterocyclic benzhydrylamine core is described. The corresponding air‐stable palladium complexes are obtained in high yields and fully characterized by NMR spectroscopy and X‐ray structure determination. These new phosphane‐free catalytic systems proved efficient in the Suzuki–Miyaura reaction, enabling us to obtain biaryl products in good yields, also for reactions with o‐substituted phenyl chlorides as starting materials. The effects of both electronic and steric modulations at the benzhydrylamine core on the catalytic activity are also described.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Synthesis and Molecular Structure of Symmetrical 1,8‐Diarylnaphthalenes

“…This prompted us to use a phosphanefree catalytic system (Scheme 1, Table 1). [14] Indeed, 1,8-dibromonaphthalene was coupled to a series of commercially available boronic acids under Suzuki conditions in the presence of cesium carbonate and 1 % palladium(II) complex 2 [13] in N,N-dimethylformamide (DMF)/water (95:5), which led to the corresponding diarylnaphthalenes in good isolated yields. Table 1 summarizes the results obtained under the aforementioned conditions.…”

“…In addition, we recently described the preparation of new nitrogen-based palladium(II) complexes that were found to be stable and highly efficient in the syntheses of biphenyls. [13] In the second part of this paper, we report the results of our investigations into the molecular structure of 1,8-diarylnaphthalenes by means of 1 H NMR and X-ray analysis, with particular emphasis on the deformation of the naphthalene core.…”

Aziridine- and Azetidine-Pd Catalytic Combinations. Synthesis and Evaluation of the Ligand Ring Size Impact on Suzuki-Miyaura Reaction Issues

“…The coupling between 4-bromonitrobenzene and 4-tolylboronic acid was chosen as the model coupling reaction (Scheme 4). Gratifyingly, running the reaction at room temperature for 10 h, using 1% of catalytic loading and base/solvent combination (Cs2CO3 and DMF/H2O) as already reported for benzhydrylamines [20][21][22][23][24], allowed us to identify 4-nitro-4′-methyl biphenyl 5 in the crude material 1 H NMR spectra. Various conversions were observed ranging from 10% to 50% evidencing that our catalytic systems were able to trigger Suzuki-Miyaura coupling at room temperature.…”

“…Catalysts 2017, 7, 27 2 of 9 based scaffolds as well as combinations of pyridines linked to flexible alkylamine arms or rigid cycloalkylamines such as piperidines have been successfully developed in recent years [17][18][19][20][21][22][23]. In this communication, we describe new ligands based on strained aza-heterocycles such as aziridines and azetidines.…”

“…If phosphorus-based catalytic systems dominated this area during the last decades, nitrogen-containing ligands revealed recently useful and appear as a pertinent alternative. In this context, ligands incorporating pyridyl-based scaffolds as well as combinations of pyridines linked to flexible alkylamine arms or rigid based scaffolds as well as combinations of pyridines linked to flexible alkylamine arms or rigid cycloalkylamines such as piperidines have been successfully developed in recent years [17][18][19][20][21][22][23]. In this communication, we describe new ligands based on strained aza-heterocycles such as aziridines and azetidines.…”