1128-27-4Relevant academic research and scientific papers
Homo- and Heterodinuclear Head-to-Head or Head-to-Tail Complexes of Rhodium(I) and Iridium(I) with C2,N3 or C8,N9 Bridging Azolato Ligands
Cepa, Steffen,B?hmer, Maximilian,Roelfes, Florian,Tan, Tristan Tsai Yuan,Dielmann, Fabian,Hahn, F. Ekkehardt
, p. 1982 - 1990 (2019)
Reaction of in situ lithiated N-methylimidazole or 1,5,6-trimethylbenzimidazole with [M(cod)(μ-Cl)]2 (M = Rh, Ir) led to the exclusive formation of the homodinuclear head-to-head complexes [2]-[5], where the metal centers are bridged by two C,N-coordinated azolato ligands. The two metal centers are each coordinated by one cod ligand and either two carbon or two nitrogen donors of the azolato ligands. Access to a heterodinuclear Ir/Rh complex [6] was achieved via the lithiated iridium complex [7] and addition of an equimolar amount of [Rh(cod)(μ-Cl)]2. Deprotonation of caffeine with lithium diisopropylamide and addition of [M(cod)(μ-Cl)]2 (M = Rh, Ir) led to mixtures of the head-to-head (M = Ir: [8H-H]; M = Rh: [9H-H]) and head-to-tail isomers (M = Ir: [8H-T]; M = Rh: [9H-T]) of the homodinuclear complexes. The molecular structures of the homo- and heterodinuclear complexes [3], [5]·2C6H5F, [6]·2C6H5F, and [9H-T]·C4H8O have been determined by X-ray diffraction studies.
Photoinduced Bergman cycloaromatization of imidazole-fused enediynes
Zhao, Zhengrong,Peacock, Justin G.,Gubler, Daniel A.,Peterson, Matt A.
, p. 1373 - 1375 (2005)
A series of 4,5-bis-(alkyn-1-yl)imidazoles-'imidazole-fused' enediynes-were synthesized and their reactivities in photoinduced Bergman cycloaromatization reactions were determined. The more conformationally rigid analogues gave cycloaromatized products in good yields upon irradiation (450 W low-pressure mercury lamp, ambient temperature). A bicyclic analogue (3) was shown to cleave supercoiled plasmid DNA.
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
, p. 6316 - 6319 (2016)
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.
Unusual NMR spectral properties of the 1,2-dicyanoethyl alkyl ligand in organocobaloximes. Structure of the organocobalt complex trans-bis(dimethylglyoximato)-(1,2-dicyanoethyl)(1,5,6-trimethylbenzimidazole) cobalt(III)
Charland, Jean-Pierre,Attia, Wahib M.,Randaccio, Lucio,Marzilli, Luigi G.
, p. 1367 - 1375 (1990)
The 1,2-dicyanoethyl ligand has been reported to exhibit unusual dynamic processes in certain organocobaloxime complexes. The crystal and molecular structures of the complex trans-bis(dimethylglyoximato)(1,2-dicyanoethyl)(1,5,6-trimethylbenzimidazole) cobalt(III)-0.5-ethanol, Me3BzmCo-(DH)2CH(CN)CH2CN, are reported. The compound crystallizes in space group P1, triclinic, with a = 7.721 (1) ?, b = 11.845 (2) ?, c = 15.078 (3) ?, α = 79.09 (2)°, β = 80.65 (2)°, γ = 75.65 (2)°, V = 1320.0 ?3, Z = 2, Dmeasd = 1.38 g cm-3, Dcalcd = 1.39 g cm-3, and R = 0.051 for 5261 independent reflections. The Co-C bond distance of 2.061 (3) ? is slightly shorter than that of 2.076 (2) ? found in the structure of the isopropyl analogue, whereas the Co-N(Me3Bzm) bond length (2.031 (3) ?) is shorter than that in the isopropyl analogue (2.097 (2) ?). Hence, the 1,2-dicyanoethyl and isopropyl groups have similar bulk properties but different trans influences. The rate constants, k1, were determined for dissociation of Me3Bzm from six Me3BzmCo(DH)2R complexes where R ranges from weak donors such as CH2CF3 to strong donors and CH(CH3)2. High-field 1H NMR spectroscopy showed that the CH(CN)CH2CN proton pattern, which is distorted by second-order effects, is greatly affected by temperature and the trans influence of L. A deuteration study in pyridine-d5/D2O revealed no exchange of the -CH(CN)CH2CN after 2 months at ambient temperature. These results militate against any unusually rapid dynamic processes involving the CH(CN)CH2CN group. Rather, previous NMR spectral observations at low field could be understood as arising from the peculiar 1H NMR spectral characteristics of these compounds.
Using Methanol as a Formaldehyde Surrogate for Sustainable Synthesis of N-Heterocycles via Manganese-Catalyzed Dehydrogenative Cyclization
Li, Yibiao,Liu, Qiang,Shao, Zhihui,Yuan, Shanshan
supporting information, (2022/02/23)
The development of an efficient and sustainable synthetic route for formaldehyde production from renewable feedstock, especially in combination with a subsequent transformation to straightforwardly construct valuable chemicals, is highly desirable. Herein, we report a novel manganese-catalyzed dehydrogenative cyclization of methanol as a formaldehyde surrogate with a variety of dinucleophiles for facile synthesis of N-heterocycles. The in situ generated formaldehyde via catalytic methanol dehydrogenation can be selectively trapped by diverse dinucleophiles to avoid several possible side reactions. The utility of this transformation is further highlighted by its successful application to the synthesis of 13C-labeled N-heterocycles using 13CH3OH as a readily accessible 13C-isotope reagent.
Iodine(I) and Silver(I) Complexes of Benzoimidazole and Pyridylcarbazole Derivatives
Rissanen, Kari,Siepmann, Marcel,Taipale, Essi,Truong, Khai-Nghi
supporting information, p. 17412 - 17419 (2021/10/19)
The synthesis of iodine(I) complexes with either benzoimidazole or carbazole-derived sp2 N-containing Lewis bases is described, as well as their corresponding silver(I) complexes. The addition of elemental iodine to the linear two-coordinate Ag
Efficient N-Heterocyclic Carbene/Ruthenium Catalytic Systems for the Alcohol Amidation with Amines: Involvement of Poly-Carbene Complexes?
Cheng, Hua,Xiong, Mao-Qian,Zhang, Ni,Wang, Hua-Jing,Miao, Yang,Su, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
, p. 4338 - 4345 (2018/09/06)
The atom-economic direct amidation of alcohols with amines has been recently highlighted as an attractive and promising transformation. Among the versatile reported catalytic systems, in situ generated N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic systems have demonstrated their advantages such as easy operation and use of commercial Ru compounds. However, the existing catalyst loadings are relatively high, and additional insights for the in situ catalyst generation are still not well-documented. In this work, a variety of benzimidazole-based NHC precursors were initially synthesized. Through the screening of various NHC precursors and other reaction conditions, active in situ catalytic systems were discovered for the efficient amide synthesis. Notably, the catalyst loading is as low as 0.5 mol %. Furthermore, additional experiments were performed to validate the rationale for the superiority of the current catalytic systems over our previous system. It was observed that the ligand structure is one of the reasons for the higher activity. In addition, the higher ratio of the NHC precursor/[Ru] is another important factor for the improvement. Further HR-MS analysis identified the formation of two mono-NHC-Ru species as major species and two Ru species bearing multiple NHC ligands as minor species. Hopefully, the efficient and readily-accessible catalytic systems reported herein could demonstrate great potential for further practical applications.
Selective C-H trifluoromethylation of benzimidazoles through photoredox catalysis
Gao, Guo-Lin,Yang, Chao,Xia, Wujiong
supporting information, p. 1041 - 1044 (2017/02/05)
The protocol presented here is a new strategy for visible light induced C-H trifluoromethylation at C4 of benzimidazoles using Togni's reagent in the presence of fac-Ir(ppy)3. Its advantages are its operational simplicity, mild reaction conditions, low catalyst loading and wide substrate scope in which electron-withdrawing, electron-donating groups and different protecting groups are tolerated.
Supercritical methanol as solvent and carbon source in the catalytic conversion of 1,2-diaminobenzenes and 2-nitroanilines to benzimidazoles
Sun, Zhuohua,Bottari, Giovanni,Barta, Katalin
, p. 5172 - 5181 (2015/12/08)
Benzimidazoles and N-methylbenzimidazoles were synthesized by simply heating 1,2-diaminobenzenes in supercritical methanol over copper-doped porous metal oxides. These catalysts were derived from synthetic hydrotalcites that only contain earth-abundant starting materials. The carbon equivalents needed for the construction of the benzimidazole core originated from the solvent itself, which is known to undergo reforming to hydrogen and carbon monoxide through the formation of a formaldehyde intermediate. A variety of 1,2-diaminobenzenes were converted to the corresponding mixtures of benzimidazoles and N-methylated analogues in good yields. Interestingly, the more challenging, but readily available 2-nitroanilines, which require an additional reduction step prior to cyclization, could also be successfully converted to benzimidazoles in high selectivity. Furthermore, various other alcohols were applied besides methanol, to obtain 2-alkyl- and 1,2-dialkylbenzimidazoles. Preliminary mechanistic insights into the origins of N-alkylation as well as the reactivity of the nitro derivatives are discussed.
IMIDAZOPYRIDAZINE COMPOUNDS
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Page/Page column 48, (2008/06/13)
The present invention relates to novel substituted imidazo[1,2-b] pyridazine compounds of Formula (I) pharmaceutical compositions thereof, and the use such compounds as corticotropin releasing factor 1 (CRF1) receptor antagonists in the treatment of psychiatric disorders and neurological diseases.
