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4,5-Dihydro-imidazol-2-ylidene-linked palladium complexes as catalysts for the direct C-H bond arylation of azoles
(Wiley, 2022) Kaloglu, Murat; Ozdemir, Namik; Ozdemir, Ismail
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, unsaturated ring carbene ligands such as benzo[d]imidazol-2-ylidene and imidazol-2-ylidene were used. However, the use of saturated ring carbene ligands such as 4,5-dihydro-imidazol-2-ylidene has been highly limited. Therefore, in this study, four novel 4,5-dihydro-1H-imidazolium salts were synthesized as saturated ring carbene precursors. Then, well-defined air- and moisture-stable four novel PEPPSI-type palladium-complexes with 4,5-dihydro-imidazol-2-ylidene ligands were prepared. All synthesized carbene precursors and palladium-complexes were structurally characterized by different spectroscopic and analytical techniques. Further structural characterization of two of the palladium-complexes was performed by single-crystal X-ray diffraction. Next, the palladium-complexes were tested in the direct arylation of azoles such as 4,5-dimethylthiazole and 1-methyl-1H-imidazole with (hetero)aryl halides in presence of 1 mol% catalyst loading at 120 degrees C. The results showed that these novel palladium complexes are effective catalysts.
Amine-fnctionalized silver and gold N-heterocyclic carbene complexes: Synthesis, characterization and antitumor properties
(Elsevier Science Sa, 2019) Kizrak, Umran; Ciftci, Osman; Ozdemir, Ilknur; Gurbuz, Nevin; Dusunceli, Serpil Demir; Kaloglu, Murat; Mansour, Lamjed
Diisopropilamine-tethered benzimidazolium salts have been prepared as precursors for Ag(I)-NHC and Au(I)-NHC complexes. These NHC ligands were metallated with Ag2O on moderate conditions to give novel silver-NHC complexes. Gold-NHC complexes have been obtained by transmetalation using the silver-NHC precursor. The structures of all compounds were characterized by H-1 NMR, C-13 NMR, IR and elemental analysis techniques. The cytotoxic properties of the silver(I) and gold(I) complexes have been assessed in various human cancer lines, including cisplatin-sensitive and resistant cell. IC50 values of these four complexes were determined by the MTS based assay on three human cancer cell lines (SHSY5Y, HTC116 and HEP3B) and human healthy cell line (HF). These silver and gold N-heterocyclic carbene complexes have been highlighted metal-based cancer therapeutic agent with unique structures and functions. These strategies provide exciting opportunities for discovering new type metalodrug. (C) 2019 Elsevier B.V. All rights reserved.
Applications of quinoxaline-bridged bis(benzimidazolium) salts as ligand sources for the palladium-catalyzed Suzuki and Heck cross-coupling reactions in an aqueous medium
(Wiley-V C H Verlag Gmbh, 2022) Dusunceli, Serpil Demir; Sahan, Mehmet Hanifi; Kaloglu, Murat; Ustun, Elvan; Ozdemir, Ismail
In the present work, quinoxaline-bridged bis(benzimidazolium) salts were prepared by the reaction of 2,3-bis(bromomethyl) quinoxaline and 1-substituted benzimidazole. The structures of the bis(benzimidazolium) salts were characterized by NMR, FT-IR, and elemental analysis techniques. Also, the photophysical properties of salts were investigated by UV-Vis absorption and fluorescence emission spectroscopy. Next, these quinoxaline bridged bis(benzimidazolium) salts were used as bidentate benzimidazol-2-ylidene ligand precursors in the palladium-catalyzed Suzuki-Miyaura and Mizoroki-Heck cross-couplings. These salts exhibited moderate-to-high activity in the palladium-catalyzed cross-coupling reactions.
Copper-Catalysed Allylic Substitution Using 2,8,14,20-Tetrapentylresorcinarenyl-Substituted Imidazolium Salts
(Wiley-V C H Verlag Gmbh, 2015) Kaloglu, Murat; Sahin, Neslihan; Semeril, David; Brenner, Eric; Matt, Dominique; Ozdemir, Ismail; Kaya, Cemal
Unsymmetrical imidazolium salts, each having one nitrogen atom (N1) substituted by a cavity-shaped TPR group (TPR = 2,8,14,20-tetrapentylresorcinaren-5-yl), were tested in situ as proligands for the copper-catalysed allylic arylation of cinnamyl bromide with arylmagnesium halides. The catalytic systems produced mixtures of linear (l) and branched (b) arylated compounds in variable proportions, with the b/l ratio being the highest (78:22) for the most crowded imidazolium salt used, namely that in which the second nitrogen atom (N2) was substituted by a mesityl group. An N-heterocyclic carbene complex obtained from one of the imidazolium salts was characterised by an X-ray diffraction study.
The direct C(sp2)-H functionalization and coupling of aromatic N-heterocycles with (hetero)aryl bromides by [PdX2(imidazolidin-2-ylidene)(Py)] catalysts
(Elsevier Science Sa, 2021) Kaloglu, Murat; Slimani, Ichraf; Ozdemir, Namik; Gurbuz, Nevin; Hamdi, Naceur; Ozdemir, Ismail
In this study, a series of air- and moisture-stable imidazolidin-2-ylidene-based new palladium complexes with the general formula [PdX2(NHC)(Py)] were synthesized (NHC = N-heterocyclic carbene, Py = pyridine, X = Cl or I). The structures of the palladium complexes were characterized by different techniques such as H-1 NMR, C-13 NMR, FT-IR spectroscopy and elemental analysis. The more detailed structural characterization of one of the palladium complex was determined by single-crystal X-ray diffraction study. The catalytic activities of all palladium complexes were tested in the direct arylation of five-membered aromatic N-heterocycles such as 3,5-dimethylisoxazole and 1-methyl-1H-pyrrole-2-carboxaldehyde with (hetero)aryl bromides in presence of 1 mol% catalyst loading at 120 degrees C. Desired products were obtained in moderate to good yields. (C) 2021 Elsevier B.V. All rights reserved.
Direct C-H Bond Arylation of C2-Blocked Pyrrole with Aryl Halides Using Palladium(II)-N-Heterocyclic Carbene Catalysts
(Wiley-V C H Verlag Gmbh, 2018) Kaloglu, Murat; Kaloglu, Nazan; Ozdemir, Ismail
Herein we report synthesis of seven new palladium(II)-NHC complexes with the general formula [PdX2(NHC)(2)], (NHC=1,3-dialkylbenzimidazol-2-ylidene, X = Cl or Br). The structures of all the new compounds were characterized by (HNMR)-H-1, (CNMR)-C-13, FT-IR spectroscopy and elemental analysis techniques. The catalytic activities of palladium(II)-NHC complexes were tested in the direct C-H bond arylation of C2-blocked pyrrole with various aryl halides in presence of 1mol% catalyst loading at 120 degrees C for 1-16 h. Under the given conditions, palladium(II)-NHC complexes showed the good catalytic performance for the direct C-H bond arylation of C2-blocked pyrrole with aryl bromides, and with readily available and inexpensive aryl chlorides. In all cases, the C-H bond arylation regioselectively produced C5-arylated products in moderate to high yields.
The direct C4-arylation of 3,5-dimethylisoxazole with aryl bromides catalyzed by imidazolidin-2-ylidene based palladium-PEPPSI complexes
(Elsevier Science Sa, 2020) Kaloglu, Murat; Ozdemir, Ismail
In this study, the synthesis and characterization of four new imidazolinium salts as carbene precursors and their corresponding four new PEPPSI-type (PEPPSI = Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation) palladium complexes were reported. The structures of these new compounds were characterized by spectroscopic and analytical techniques. The catalytic activities of all palladium complexes were evaluated in the direct C4-arylation of 3,5-dimethylisoxazole with para-substituted aryl bromides, ortho-substituted aryl bromides and heteroaryl bromides. A range of functional groups such as methoxy, acetyl, formyl, fluoro, trifluoromethyl, nitrile or tert-butyl on the aryl bromide were succesfully tolerated, and good yields were generally obtained in presence of 1 mol% catalyst loading at 120 degrees C.
Direct CH Bond Activation of Benzoxazole and Benzothiazole with Aryl Bromides Catalyzed by Palladium(II)-N-heterocyclic Carbene Complexes
(Wiley-V C H Verlag Gmbh, 2018) Kaloglu, Murat; Kaloglur, Nazan; Ozdemir, Ismail
Herein, we report that a series of novel palladium(II)-NHC complexes (NHC=N-heterocyclic carbene) were synthesized. The structures of all novel complexes were characterized by H-1 NMR, C-13 NMR, FT-IR spectroscopy and elemental analysis techniques. These palladium(II)-NHC complexes were tested as efficient catalysts in the direct CH bond activation of benzoxazole and benzothiazole with aryl bromides in the presence of 1 mol% catalyst loading at 150 degrees C for 4 h. Under the given conditions, various aryl bromides were successfully applied as the arylating reagents to achieve the 2-arylbenzoxazoles and 2-arylbenzothiazoles in acceptable to high yields.
The first use of [PdBr2(imidazolidin-2-ylidene)(pyridine)] catalysts in the direct C-H bond arylation of C2-substituted furan and thiophene
(Springer, 2021) Kaloglu, Murat; Kaloglu, Nazan; ozdemir, Namik; ozdemir, Ismail
N-Heterocyclic carbene (NHC)-linked PEPPSI-type palladium complexes have recently been used in the direct C-H bond arylation of heteroarenes. However, in most of the published works, NHC ligands containing benzimidazole and imidazole ring have been used, but using NHC ligands containing saturated imidazoline ring is quite rare. Therefore, in this study, four new 1,3-disubstituted imidazolinium salts as NHC ligand precursors, and their four new PEPPSI-type palladium complexes were synthesized. The structures of all new compounds were fully characterized by different spectroscopic and analytical techniques. The more detailed structural characterization of one of the palladium complexes was determined by single-crystal X-ray diffraction study. The catalytic activities of all palladium complexes were evaluated in the direct C-H bond arylation of the 2-acetylfuran and 2-acetylthiophene with (hetero) aryl bromides and readily available and inexpensive aryl chlorides in presence of 1 mol% catalyst loading at 120 degrees C. Under the given conditions, (hetero)aryl halides were successfully applied as the arylating reagents to achieve the C5-arylated furans and thiophenes in acceptable to high yields. [GRAPHICS] .
The first used butylene linked bis(N-heterocyclic carbene)-palladium-PEPPSI complexes in the direct arylation of furan and pyrrole
(Elsevier Science Sa, 2020) Kaloglu, Murat; Dusunceli, Serpil Demir; Ozdemir, Ismail
We reported the synthesis and characterization of butylene linked bis-benzimidazole based N-heterocyclic carbene (NHC) precursors and their PEPPSI-type bimetallic Pd-complexes, and we implemented its activities in the direct C5-arylation of 2-acetylfuran and 1-methylpyrrole-2-carboxaldehyde with various aryl bromides. The catalytic activities of the synthesized palladium-complexes were found to be very high. These complexes were fully characterized by different techniques such as H-1 NMR, C-13 NMR, FT-IR spectroscopy and elemental analysis. (C) 2020 Elsevier B.V. All rights reserved.
Half-sandwich ruthenium-carbene catalysts: Synthesis, characterization, and catalytic application in the N-alkylation of amines with alcohols
(Elsevier Science Sa, 2019) Kaloglu, Murat
In this study, the synthesis and characterization of new half-sandwich ruthenium complexes containing oxygen functionalised N-aryl and N-alkyl benzimidazol-2-ylidene ligands have been reported. All ruthenium complexes were tested as catalysts for a wide range of substrates in the N-alkylation of secondary cyclic amines such as pyrrolidine and piperidine, and 4-methylaniline which was a primary aromatic amine with alcohols by hydrogen-borrowing process. The catalytic reactions were performed with 1 mol% catalyst loading at 120 degrees C, 16 h under solvent-free conditions. All ruthenium complexes showed excellent catalytic activity, and N-alkylated products were obtained selectively.
The Influence of Imidazolylidene Ligands with Bulky Resorcinarenyl Substituents on Catalysts for Suzuki-Miyaura Coupling
(Wiley-V C H Verlag Gmbh, 2016) Kaloglu, Murat; Semeril, David; Brenner, Eric; Matt, Dominique; Ozdemir, Ismail; Toupet, Loic
PEPPSI-type imidazolylidene palladium complexes having their carbenic ring N-substituted with an aryl ring and a cavity-shaped unit [25,26,27,28-tetrapropyloxycalix[4]aren-5-yl or 6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]aren-5-yl (TPR)] have been prepared and assessed in Suzuki-Miyaura cross-couplings. Remarkable efficiency in the coupling of aryl chlorides with sterically hindered arylboronic acids was observed for the carbene ligand having its N atoms (N1, N2) substituted by a mesityl and a TPR group, respectively. This good performance possibly arises from strong steric interactions between the pentyl-substituted cavitand unit and the catalytic centre, which favours reductive elimination. Two of the imidazolium salts used for complex synthesis were characterised by X-ray diffraction analysis.
N-Heterocyclic carbene-palladium catalysts for the direct arylation of pyrrole derivatives with aryl chlorides
(Beilstein-Institut, 2013) Ozdemir, Ismail; Gurbuz, Nevin; Kaloglu, Nazan; Dogan, Oznur; Kaloglu, Murat; Bruneau, Christian; Doucet, Henri
New Pd-NHC complexes have been synthesized and employed for palladium-catalyzed direct arylation of pyrrole derivatives by using electron-deficient aryl chlorides as coupling partners. The desired coupling products were obtained in moderate to good yields by using 1 mol % of these air-stable palladium complexes. This is an advantage compared to the procedures employing air-sensitive phosphines, which have been previously shown to promote the coupling of aryl chlorides with heteroarenes.
N-Heterocyclic Carbenes: Useful Ligands for the Palladium-Catalysed Direct C5 Arylation of Heteroaromatics with Aryl Bromides or Electron-Deficient Aryl Chlorides
(Wiley-V C H Verlag Gmbh, 2010) Ozdemir, Ismail; Gok, Yetkin; Ozeroglu, Oezlem; Kaloglu, Murat; Doucet, Henri; Bruneau, Christian
New Pd-N-heterocyclic carbene complexes have been prepared and employed for palladium-catalysed direct arylation of heteroaromatic derivatives by using aryl halides. These catalyst precursors promote the coupling of challenging aryl halides such as deactivated or congested aryl bromides and also activated aryl chlorides. This procedure employs only 1 mol-% of an air-stable palladium complex. This is a practical advantage over the procedures that employ palladium attached to air-sensitive phosphane ligands, which are often used to promote the coupling of such aryl halides.
Novel benzimidazol-2-ylidene carbene precursors and their silver(I) complexes: Potential antimicrobial agents
(Pergamon-Elsevier Science Ltd, 2016) Kaloglu, Murat; Kaloglu, Nazan; Ozdemir, Ilknur; Gunal, Selami; Ozdemir, Ismail
Novel benzimidazolium salts were synthesized as N-heterocyclic carbene (NHC) precursors, these NHC precursors were metallated with Ag2O in dichloromethane at room temperature to give novel silver (I)-NHC complexes. Structures of these benzimidazolium salts and silver(I)-NHC complexes were characterized on the basis of elemental analysis, H-1 NMR, C-13 NMR, IR and LC-MS spectroscopic techniques. A series of benzimidazolium salts and silver(I)-NHC complexes were tested against standard bacterial strains: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungal strains: Candida albicans and Candida tropicalis. The results showed that benzimidazolium salts inhibited the growth of all bacteria and fungi strains and all silver(I)-NHC complexes performed good activities against different microorganisms. (C) 2016 Elsevier Ltd. All rights reserved.
Palladium N-Heterocyclic Carbene Pre-catalysts Bearing Different Ancillary Ligands for the Buchwald-Hartwig Amination of Cyclic Secondary Amines with Aryl Chlorides
(Springer, 2024) Kaloglu, Murat; Ozdemir, Ismail
Six novel palladium N-heterocyclic carbene complexes bearing different ancillary ligands such as pyridine, 1-methylimidazole, 4,5-dimethylthiazole and 3-bromoquinoline have been successfully prepared in a one-step process. These complexes were used as pre-catalysts in the Buchwald-Hartwig amination of cyclic secondary amines with aryl chlorides. A range of cyclic secondary amines were tolerated to a wide variety of aryl chlorides in presence of 1 mol% catalyst loading under mild conditions. Under the tested reaction conditions, the expected N-arylamines were obtained in moderate to high yields. The results showed that these novel palladium complexes are effective catalysts for the Buchwald-Hartwig amination.Graphic Abstract
Palladium(II)-N-Heterocyclic Carbene Complexes: Efficient Catalysts for the Direct C-H Bond Arylation of Furans with Aryl Halides
(Wiley, 2018) Kaloglu, Murat; Ozdemir, Ismail
This paper contains the synthesis and characterization of the seven new benzimidazolium salts and their corresponding new palladium(II)-NHC complexes with the general formula [PdX2(NHC)(2)], (NHC=N-heterocyclic carbene, X=Cl or Br), and also their catalytic activity in direct C-H bond arylation of 2-substituted furan derivatives with aryl bromides and aryl chlorides. Under the optimal conditions, these palladium(II)-NHC complexes showed the good catalytic performance for the direct C-H bond arylation of 2-substituted furans with (hetero)aryl bromides, and with readily available and inexpensive aryl chlorides. The C-H bond arylation regioselectively produced C5-arylated furans by using 1mol% of the palladium(II)-NHC catalysts in moderate to high yields.
Palladium(II)-N-heterocyclic carbene-catalyzed direct C2-or C5-arylation of thiazoles with aryl bromides
(Pergamon-Elsevier Science Ltd, 2018) Kaloglu, Murat; Ozdemir, Ismail
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 H-1 NMR, C-13 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(degrees)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. (C) 2018 Published by Elsevier Ltd.
Palladium-carbene catalyzed direct arylation of five-membered heteroaromatics
(Elsevier, 2020) Kaloglu, Murat; Kaloglu, Nazan; Ylidirim, Ilkay; Ozdemir, Namik; Ozdemir, Ismail
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. (C) 2020 Elsevier B.V. All rights reserved.
Palladium-PEPPSI-NHC Complexes Bearing Imidazolidin-2-Ylidene Ligand: Efficient Precatalysts for the Direct C5-Arylation of N-Methylpyrrole-2-Carboxaldehyde
(Springer, 2021) Kaloglu, Murat; Kaloglu, Nazan; Ozdemir, Ismail
The Pd-catalyzed direct arylation of pyrroles is an important research field for organic synthesis and catalysis chemistry. However, imidazolidin-2-ylidene based Pd-NHC complexes (NHC=N-heterocyclic carbene) have not yet been employed as catalysts for the direct C5 mono-arylation of C2-substituted N-methylpyrrole derivatives with aryl halides. Therefore, we now report the synthesis and characterization of new 1,3-bis(substituted benzyl) imidazolinium salts as carbene precursors, and their corresponding Pd-PEPPSI-NHC type complexes (PEPPSI=Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation). The catalytic properties of these complexes have been evaluated in the direct C5 mono-arylation of N-methylpyrrole-2-carboxaldehyde with a wide variety of (hetero)aryl halides. This environmentally attractive procedure has also been found to be tolerant to a wide variety of functional groups on the aryl halides such as formyl, acetyl, nitrile, fluoro or trifluoromethyl, and good yields have been obtained in presence of 1 mol% catalyst loading at 120 degrees C. [GRAPHICS] .

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