1826-24-0Relevant articles and documents
4,5-Dihydro-imidazol-2-ylidene-linked palladium complexes as catalysts for the direct C-H bond arylation of azoles
?zdemir, ?smail,?zdemir, Nam?k,Kalo?lu, Murat
, (2022/01/11)
Recently, PEPPSI-type palladium-complexes bearing N-heterocyclic carbene (NHC) ligand have commonly been used as the effective catalysts in the direct arylation of heteroaromatic compounds. In most of previous studies catalyzed by such complexes, unsatura
Direct arylation of heteroaromatic compounds by Pd(OAc)2/tetrakis(Nbenzimidazoliummethyl)benzene salt system
?zdemir, ?smail,Ulu, ?znur Do?an
, p. 286 - 295 (2021/08/19)
Six novel tetrakis(N-benzimidazoliummethyl)benzene salts were synthesized using 1,2,4,5-tetrakis-(bromomethyl)benzene with 1-alkylbenzimidazole. The structures of all isolated compounds were elucidated based on spectroscopic methods (1H and 13C NMR, and FT-IR spectroscopy) and were investigated for their catalytic activities in the direct arylation of 2-n-propylthiazole, 2-n-buthyltiophene, 2-n-butylfuran, and 4,5-dimethylthiazole. All synthesized salts showed high catalytic activity for direct arylation of heteroaromatic compounds.
Arylation of heterocyclic compounds by benzimidazole-based N-heterocyclic carbene-palladium(II) complexes
?ahin, Neslihan,Gürbüz, Nevin,Karab?y?k, Hande,Karab?y?k, Hasan,?zdemir, ?smail
, (2019/12/25)
Specific C–H bond can be activated for arylation using aryl halide without the aid of directing the group in the case of electron-rich heteroarenes. The ability to readily generate halo substituted arylated heteroarenes is important in organic chemistry s
Synthesis, structures and catalytic activity of Pd(II) saccharinate complexes with monophosphines in direct arylation of five-membered heteroarenes with aryl bromides
Yilmaz, Veysel T.,Icsel, Ceyda,Turgut, Omer R.,Aygun, Muhittin,Evren, Enes,Ozdemir, Ismail
, (2019/11/11)
A number of new Pd(II) saccharinate (sac) complexes bearing a range of phenyl (Ph), cyclohexyl (Cy) and alkyl (Me and Et) substituted tertiary phosphine ligands with systematically changing electronic and steric properties, namely trans-[PdCl(sac)(L)2] (L = PPh3 (1); PPh2Cy (3)), trans-[Pd(sac)2(H2O)(L)] (L = PPh3 (2); PPh2Cy (5)), trans-[Pd(sac)2(L)2] (L = PPh2Cy (4); PPhCy2 (6); PCy3 (8)), [PdCl(sac)(PCy3)(DMSO)] (7), trans-[Pd(sac)2(PPh2Me)(DMSO)] (9) and cis-[M(sac)2(L)2] (L = PPhMe2 (10); PPh2Et (11); PPhEt2 (12)), were synthesized and structurally characterized. The Pd(II) complexes were applied for direct C2/C5 arylation of five-membered heteroarenes such as furan, thiophene and thiazole derivatives with aryl bromides. Notably, arylation products up to 99% yields were obtained in the presence of the Pd(II) complexes. The catalytic mechanism of the direct arylation was proposed to proceed via a Pd(0)/Pd(II) pathway, due to elimination of the sac ligand in the Pd(II) complexes during catalysis.
Palladium-carbene catalyzed direct arylation of five-membered heteroaromatics
?zdemir, ?smail,?zdemir, Nam?k,Kalo?lu, Murat,Kalo?lu, Nazan,Y?ld?r?m, ?lkay
, (2020/01/08)
Due to the industrial importance of bi(hetero)arenes, the synthesis of these compounds by homogeneous Pd-catalyzed direct arylation is an important research topic in modern organic chemistry. In this study, PEPPSI-type, (PEPPSI = Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation), new Pd-catalysts with N-heterocyclic carbene ligand were synthesized, and they were used as catalysts in the synthesis of bi(hetero)arenes by direct arylation process. The structures of Pd-carbene complexes were elucidated by different spectroscopic and analytical techniques such as NMR, FT-IR and elemental analysis. The more detailed structural characterization of one of the complexes was determined by single-crystal X-ray diffraction study. Pd-carbene complexes were used as effective catalysts in the direct arylation of five-membered heteroaromatics such as thiophene, furan and thiazole derivatives with (hetero)aryl bromides for 1 h, in the presence of 1 mol% of catalyst loading, and successful results were obtained.
Discovery of first-in-class thiazole-based dual FFA1/PPARδ agonists as potential anti-diabetic agents
Li, Zheng,Chen, Yueming,Zhou, Zongtao,Deng, Liming,Xu, Yawen,Hu, Lijun,Liu, Bing,Zhang, Luyong
, p. 352 - 365 (2019/01/04)
The free fatty acid receptor 1 (FFA1 or GPR40) and peroxisome proliferator-activated receptor δ (PPARδ) have attracted a lot of attention due to their role in promoting insulin secretion and sensibility, respectively, which are two major features of diabetes. Therefore, the dual FFA1/PPARδ agonists would increase insulin secretion and sensibility by FFA1 and PPARδ activation. In this study, we hybrid FFA1 agonist AM-4668 with PPARδ agonist GW501516, leading to the identification of orally bioavailable dual agonist 32, which revealed high selectivity over other PPARs. Moreover, compound 32 exhibited good pharmacokinetic profiles with high plasma concentration, sustained half-life and low clearance in vivo. During the hypoglycemic test, a dual agonist 32 enhanced the tolerance of ob/ob mice for glucose loading in a dose-dependent manner. Our results suggest that dual FFA1/PPARδ agonist could be a valuable therapy for type 2 diabetes.
Palladium(II)-N-heterocyclic carbene-catalyzed direct C2- or C5-arylation of thiazoles with aryl bromides
Kalo?lu, Murat,?zdemir, ?smail
, p. 2837 - 2845 (2018/05/08)
Herein we report, a series of new benzimidazolium chlorides as N-heterocyclic carbene (NHC) ligand and their corresponding palladium(II)-NHC complexes with the general formula [PdCl2(NHC)2] were synthesized. All new compounds were characterized by 1H NMR, 13C NMR, IR spectroscopy and elemental analysis techniques. The catalytic activity of palladium(II)-NHC complexes was investigated in the direct C2- or C5-arylation of thiazoles with aryl bromides in presence of palladium(II)-NHC at 150 °C for 1 h. These complexes exhibited the good catalytic performance for the direct arylation of thiazoles. The arylation of thiazoles regioselectively produced C2- or C5-arylated thiazoles in moderate to high yields.
Displacement of η5-cyclopentadienyl ligands from half-sandwich: C, C -(NHC-cyanoalkyl)-nickel(II) metallacycles: Further insight into the structure of the resulting Cp-free nickelacycles and a catalytic activity study
Cardoso, Bernardo De P.,Bernard-Schaaf, Jean-Marie,Shahane, Saurabh,Veiros, Luis F.,Chetcuti, Michael J.,Ritleng, Vincent
, p. 1535 - 1547 (2018/02/09)
Four cationic C,C-(NHC-cyanoalkyl)-nickel(ii) metallacyclic complexes, [Ni{Me-NHC-CH2CH(CN)}(NCMe)](PF6) (2a), [Ni{Mes-NHC-CH2CH(CN)}(NCMe)](PF6) (2b), [Ni{Mes-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2c) and [Ni{DiPP-NHC-(CH2)2CH(CN)}(NCMe)](PF6) (2d), were prepared by the removal of the Cp ligand under acidic conditions at 0 °C from the corresponding half-sandwich nickelacycles [NiCp{R-NHC-(CH2)nCH(CN)}] (1a-1d; Cp = η5-C5H5; n = 1 or 2; R-NHC-(CH2)nCH(CN) = 1-R-3-[(CH2)nCH(CN)]-imidazol-2-ylidene). Full characterization of 2a-d by 1H and 13C{1H} NMR spectroscopy in CD3CN and pyridine-d5, ATR-FTIR spectroscopy, mass spectrometry, and CHN microanalyses established the presence of only one acetonitrile ligand per nickel atom in the solid state. A DFT structural study conducted on the cations of the methyl-substituted 5-membered nickelacycle 2a and the mesityl-substituted 6-membered cycle 2c found a small energetic cost (ΔG = 7-12 kcal mol-1) for the loss of one acetonitrile ligand from the square-planar structures existing in solution, that should be easily amenable upon solvent evaporation (ΔG? = 14 kcal mol-1 in the case of 2c). Two structures with one acetonitrile ligand could be optimized in both cases: (i) a truly T-shaped 14-electron structure with an end-on acetonitrile ligand, and (ii) a masked T-shaped structure stabilized by the π-coordination of the dangling CN group of the metallated alkyl chain, the latter being favoured by 2.4 kcal mol-1 in the case of the flexible 6-membered ring 2c. A comparison of calculated vibrational frequencies with experimental FTIR spectra ruled out π-coordination of the dangling CN group as a ν(CN) band at low frequency was absent. Complexes 2a-d thus probably exist as rare three-coordinate T-shaped 14-electron species in the solid state. Their catalytic activity was studied for the direct arylation of azoles, and 2c proved to be moderately active for the coupling of benzothiazole with aryl iodides. Mechanistic insights suggest that competing processes or a radical process catalysed by nickel particles could follow an initial reduction of 2c by the dimerization of a sacrificial amount of benzothiazole.
Direct arylation of benzoazoles with aldehydes utilizing metal-organic framework Fe3O(BDC)3 as a recyclable heterogeneous catalyst
Doan, Son H.,Nguyen, Khoa D.,Nguyen, Tung T.,Phan, Nam T. S.
, p. 1423 - 1431 (2017/01/21)
A metal-organic framework Fe3O(BDC)3 was synthesized and used as a recyclable heterogeneous catalyst for the direct arylation of azoles with benzaldehydes. Following this protocol, inexpensive and commercially available benzaldehydes could act as an aryl source for the transformation, replacing the aryl halides normally employed in the conventional cross-coupling reactions. The catalyst disclosed higher catalytic productivity for the formation of aryl-substituted azoles than various MOFs and diverse homogeneous iron catalysts. The conversion was considerably regulated by the solvent and the oxidant, and the combination of N-methyl-2-pyrrolidone with di-tert-butyl peroxide offered the best yield. Heterogeneous catalysis was verified for the reaction, and the production of aryl-substituted azoles was only feasible in the presence of the iron framework. It was possible to reuse the catalyst for the direct arylation of azoles with aldehydes while its catalytic activity was preserved for multiple cycles. To our best judgment, this direct arylation of azoles with aldehydes utilizing solid catalysts has not been previously reported.
C-H arylation and alkenylation of imidazoles by nickel catalysis: Solvent-accelerated imidazole C-H activation
Muto, Kei,Hatakeyama, Taito,Yamaguchi, Junichiro,Itami, Kenichiro
, p. 6792 - 6798 (2015/11/24)
The first nickel-catalyzed C-H arylations and alkenylations of imidazoles with phenol and enol derivatives are described. Under the influence of Ni(OTf)2/dcype/K3PO4 (dcype: 1,2-bis(dicyclohexylphosphino)ethane) in t-amyl alcohol, imidazoles can undergo C-H arylation with phenol derivatives. The C-H arylation of imidazoles with chloroarenes as well as that of thiazoles and oxazoles with phenol derivatives can also be achieved with this catalytic system. By changing the ligand to dcypt (3,4-bis(dicyclohexylphosphino)thiophene), enol derivatives could also be employed as coupling partners achieving the C-H alkenylation of imidazoles as well as thiazoles and oxazoles. Thus, a range of C2-arylated and alkenylated azoles can be synthesized using this newly developed nickel-based catalytic system. The key to the success of the C-H coupling of imidazoles is the use of a tertiary alcohol as solvent. This also allows the use of an air-stable nickel(ii) salt as the catalyst precursor.
