17583-50-5Relevant academic research and scientific papers
Synthesis of 1,3-dialkylimidazolium and 1,3-dialkylbenzimidazolium salts
Starikova,Dolgushin,Larina,Ushakov,Komarova,Lopyrev
, p. 1467 - 1470 (2003)
A number of N-alkylimidazoles and N-alkylbenzimidazoles were synthesized by reactions of imidazole and benzimidazole with alkyl halides. The reaction rate increases by a factor of 2 to 3 under conditions of microwave activation. Subsequent treatment of the resulting N-alkylazoles with alkyl halides afforded the corresponding 1,3-dialkylimidazolium and 1,3-dialkylbenzimidazolium halides.
Cyclometallated Platinum(II) Complexes with a Phenylpropene-Derived π/σ-Chelator and N-Heterocyclic Carbenes
Huynh, Han Vinh,Pham, Van Thong,Chi, Nguyen Thi Thanh
, p. 5650 - 5655 (2017)
A series of heteroleptic platinum(II) complexes of the general formula [PtX(iPrEug)(NHC)] (2–7) bearing the organometallic π/σ-chelator iPrEug (isopropyl eugenoxyacetate), with varying X (halido) and NHC (N-heterocyclic carbene) ligands derived from imidazole, benzimidazole, and triazole, were prepared and fully characterized by elemental analyses, ESI mass spectrometry, and IR and NMR spectroscopy. Complexes 3 and 5–7 were also characterized by single-crystal X-ray diffraction. These air-stable complexes are rare examples of platinum(II) compounds containing three different types of carbon donors, that is, aryl, carbene, and olefin. Unsymmetrical NHCs led to rotameric pairs of 4 and 5 exhibiting different NMR spectroscopic features. Spectroscopic studies also revealed that the introduction of a NHC leads to a weakening of the metal–olefin bond and strengthening of the metal–aryl bond. On the other hand, backbone and thus electronic variations among the NHCs show little influence on the bonding of the iPrEug chelator.
Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions
El Ali, Bassam,Fettouhi, Mohammed,Iali, Wissam,Mansour, Waseem,Suleiman, Rami
, (2021/08/09)
A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.
Novel and efficient bridged bis(N-heterocyclic carbene)palladium(II) catalysts for selective carbonylative Suzuki–Miyaura coupling reactions to biaryl ketones and biaryl diketones
El Ali, Bassam,Fettouhi, Mohammed,Mansour, Waseem
, (2020/03/23)
Bridged N,N′-substituted bisbenzimidazolium bromide salts (L1, L2, and L3) were synthesized and fully characterized. Reactions of palladium acetate with L1, L2, and L3 afforded corresponding new bridged bis(N-heterocyclic carbene)palladium(II) complexes (C1, C2, and C3) in high yields. The X-ray structure of complex C1 showed that the Pd(II) ion is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromido ligands are in the cis position, resulting in a distorted square planar geometry. The three Pd(NHC)2Br2 complexes C1, C2, and C3 were evaluated in carbonylative Suzuki–Miyaura coupling reactions of aryl boronic acids with aryl halides and displayed high catalytic activity with low catalyst loading. The coupling reactions of aryl bromides were selective towards the carbonylation product at higher carbon monoxide pressure.
Visible-light-induced aerobic oxidative desulfurization of 2-mercaptobenzimidazolesviaa sulfinyl radical
Deng, Guo-Jun,Fu, Mei,Huang, Huawen,Ji, Xiaochen,Li, Yongtong
supporting information, p. 5594 - 5598 (2020/09/21)
A mild transition-metal-free non-toxic aerobic photoredox system was found to enable highly efficient desulfurization of 2-mercaptobenzimidazoles. This viable catalytic system includes Rose Bengal in a low catalyst loading as a photosensitizer and cheap, non-toxic NaCl in a catalytic amount as an additive, combined with an oxygen atmosphere. This protocol provides an important alternative access to a broad range of benzimidazole and deuterated benzimidazole products in generally high yields with good tolerance of various synthetically and pharmaceutically useful functionalities. The mechanistic studies reveal that both single electron transfer and energy transfer probably occur in the initial step and a sulfinyl radical intermediate is involved in the key desulfurization process.
Methods of Forming Carbene-Functionalized Composite Materials
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Paragraph 0498; 0499, (2019/06/14)
Deposition of carbene monolayers that excluded starting anions, such as iodide ions, has been achieved. Anions such as iodide are a typical contaminant in carbene hydrogen carbonate salts when synthesized using the state-of-the-art method. A method is described for eliminating substantially all starting anion (e.g., iodide) contamination from the monolayer. Air stable, purified carbenes precursors were used to deposit an intact monolayer on the surface of some industrially relevant metals. The monolayer's ability to protect these metals against, for example, oxidation has been demonstrated.
Bis-benzimidazolium-palladium system catalyzed Suzuki-Miyaura coupling reaction of aryl bromides under mild conditions
Lin, Yi-Rang,Chiu, Chien-Cheng,Chiu, Huai-Tsu,Lee, Dong-Sheng,Lu, Ta-Jung
, (2017/10/05)
Bis-benzimidazolium salts were prepared successfully from commercially available and inexpensive o-phenylenediamine through a series of simple reactions. The bis-NHC-Pd complexes prepared in situ can catalyze Suzuki-Miyaura cross-coupling reaction under very mild conditions in aqueous media with excellent yields. The efficiency of this reaction is demonstrated by its compatibility with a range of functional groups. Di-ortho-substituted biaryls could be accomplished in 89–99% yields. Moreover, the rigorous exclusion of air or moisture is not required in these transformations.
N-Heterocyclic Carbenes as a Robust Platform for Surface-Enhanced Raman Spectroscopy
Dejesus, Joseph F.,Trujillo, Michael J.,Camden, Jon P.,Jenkins, David M.
, p. 1247 - 1250 (2018/02/09)
Surface-enhanced Raman spectroscopy (SERS) underpins a wide range of commercial and fundamental applications. SERS often relies on ligands, usually thiols, bound to a noble metal surface. The difficulty of straightforward thiol synthesis combined with their instability on surfaces highlights the need for alternative ligand design. We present the first example of SERS utilizing N-heterocyclic carbene ligands. A general three step synthesis is presented for functionalized NHC-CO2 adducts. These ligands are deposited on SERS-active gold film-over-nanosphere substrates (AuFONs) in solvent-free and base-free conditions, which prevents fouling. The resulting films are found to be robust and capable of postsynthetic modifications.
Non-symmetrically p-nitrobenzyl- and p-cyanobenzyl-substituted N-heterocyclic carbene-silver(I) complexes: synthesis, characterization and antibacterial studies
Subramanya Prasad,Shahini,Patil, Shivaputra A.,Huang, Xiaojun,Bugarin, Alejandro,Patil, Siddappa A.
, p. 600 - 614 (2017/02/05)
Various nitro/nitrile-functionalized benzimidazol-2-ylidene carbene complexes of silver(I) (7a–d and 11a–d) were synthesized by combination of 1-allyl/1-isopropyl/1-sec-butyl/1-isopentyl-3-(nitro/cyano-benzyl)-3H-benzimidazol-1-ium hexafluorophosphate (6a
CO2 as a C1 Source: B(C6F5)3-Catalyzed Cyclization of o-Phenylene-diamines To Construct Benzimidazoles in the Presence of Hydrosilane
Zhang, Zhenbei,Sun, Qiangsheng,Xia, Chungu,Sun, Wei
supporting information, p. 6316 - 6319 (2016/12/23)
The catalytic construction of benzimidazoles using CO2 as a carbon source represents a facile and sustainable approach to obtaining these valuable compounds. Herein, we describe the B(C6F5)3-catalyzed synthesis of benzimidazoles via cyclization of o-phenylenediamines with CO2 and PhSiH3. This metal-free catalytic route achieves the desired products in high yield under convenient reaction conditions and is applicable to a broad substrate scope. A plausible mechanism for the reaction involving a frustrated Lewis pair pathway is proposed based on spectroscopic characterization (e.g., 13C NMR) of the reaction intermediates.
