6048-82-4Relevant academic research and scientific papers
A Proton-Responsive Pyridyl(benzamide)-Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols
Kaur, Mandeep,U Din Reshi, Noor,Patra, Kamaless,Bhattacherya, Arindom,Kunnikuruvan, Sooraj,Bera, Jitendra K.
supporting information, p. 10737 - 10748 (2021/06/15)
A Cp*Ir(III) complex (1) of a newly designed ligand L1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L1H)Cl]BF4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effective catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L2)Cl]PF6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.
Unveiling the catalytic nature of palladium-N-heterocyclic carbene catalysts in the α-alkylation of ketones with primary alcohols
?etinkaya, Bekir,Ero?lu, Zafer,Gülcemal, Süleyman,Metin, ?nder,Ovezova, Mamajan
supporting information, p. 10896 - 10908 (2021/08/17)
We report herein the synthesis of four new Pd-PEPPSI complexes with backbone-modified N-heterocyclic carbene (NHC) ligands and their application as catalysts in the α-alkylation of ketones with primary alcohols using a borrowing hydrogen process and tandem Suzuki-Miyaura coupling/α-alkylation reactions. Among the synthesized Pd-PEPPSI complexes, complex2chaving 4-methoxyphenyl groups at the 4,5-positions and 4-methoxybenzyl substituents on the N-atoms of imidazole exhibited the highest catalytic activity in the α-alkylation of ketones with primary alcohols (18 examples) with yields reaching up to 95%. Additionally, complex2cwas demonstrated to be an effective catalyst for the tandem Suzuki-Miyaura-coupling/α-alkylation of ketones to give biaryl ketones with high yields. The heterogeneous nature of the present catalytic system was verified by mercury poisoning and hot filtration experiments. Moreover, the formation of NHC-stabilized Pd(0) nanoparticles during the α-alkylation reactions was identified by advanced analytical techniques.
Synthesis of α-Alkylated Ketones via Selective Epoxide Opening/Alkylation Reactions with Primary Alcohols
Gen?, Serta?,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
supporting information, p. 5229 - 5234 (2021/07/19)
A new method for converting terminal epoxides and primary alcohols into α-alkylated ketones under borrowing hydrogen conditions is reported. The procedure involves a one-pot epoxide ring opening and alkylation via primary alcohols in the presence of an N-heterocyclic carbene iridium(I) catalyst, under aerobic conditions, with water as the side product.
N-Acylcarbazoles and N-Acylindoles: Electronically Activated Amides for N-C(O) Cross-Coupling by Nlpto Ar Conjugation Switch
Buchspies, Jonathan,Rahman, Md. Mahbubur,Szostak, Roman,Szostak, Michal
, p. 4703 - 4709 (2020/06/17)
The development of new amide precursors for selective, catalytic activation of carbon-nitrogen bonds in amides is a fundamental objective of this emerging reactivity manifold. We report the palladium-catalyzed Suzuki-Miyaura cross-coupling of N-acylcarbazoles and N-acylindoles with arylboronic acids by a highly selective N-C(O) cleavage. The key amide bond ground-state destabilization stems from Nlp to Ar conjugation and enables us for the first time to achieve reactivity similar to that for N-acylsulfonamide and N-acylcarbamate activation in simple anilides.
Rhodium-Catalyzed Remote Isomerization of Alkenyl Alcohols to Ketones
Dong, Wenke,Yang, Hongxuan,Yang, Wen,Zhao, Wanxiang
supporting information, (2020/02/28)
We develop herein an efficient rhodium-catalyzed remote isomerization of aromatic and aliphatic alkenyl alcohols into ketones. This catalytic process, with a commercially available catalyst and ligand ([RhCl(cod)]2 and Xantphos), features high efficiency, low catalyst loading, good functional group tolerance, a broad substrate scope, and no (sub)stoichiometric additive. Preliminary mechanistic studies suggest that this transformation involves an iterative dissociative β-hydride elimination-migration insertion process.
C-C coupling formation using nitron complexes
Sevim, Mehmet,Kavukcu, Serdar Batikan,Kinal, Arma?an,?ahin, Onur,Türkmen, Hayati
supporting information, p. 16903 - 16915 (2020/12/18)
A series of RuII (1), RhIII (2), IrIII (3, 4), IrI (5) and PdII (6-9) complexes of the 'instant carbene' nitron were prepared and characterized by 1H- and 13C-NMR, FT-IR and elemental analysis. The molecular structures of complexes 1-4 and 6 were determined by X-ray diffraction studies. The catalytic activity of the complexes (1-9) was evaluated in alpha(α)-alkylation reactions of ketones with alcohol via the borrowing hydrogen strategy under mild conditions. These complexes were able to perform this catalytic transformation in a short time with low catalyst and base amounts under an air atmosphere. Also, the PdII-nitron complexes (6-9) were applied in the Suzuki-Miyaura C-C coupling reaction and these complexes successfully initiated this reaction in a short time (30 minutes) using the H2O/2-propanol (1.5?:?0.5) solvent system. The DFT calculations revealed that the Pd0/II/0 pathway was more preferable for the mechanism
Iridium-Catalyzed Alkylation of Secondary Alcohols with Primary Alcohols: A Route to Access Branched Ketones and Alcohols
Gen?, Serta?,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
, p. 9139 - 9152 (2020/08/14)
Under borrowing hydrogen conditions, NHC-iridium(I) catalyzed the direct or one-pot sequential synthesis of α,α-disubstituted ketones via the alkylation of secondary alcohols with primary alcohols is reported. Notably, the present approach provides a new method for the facile synthesis of α,α-disubstituted ketones and featured with several characteristics, including a broad substrate scope, using easy-to-handle alcohols as starting materials, and performing the reactions under aerobic conditions. Moreover, the selective one-pot formation of β,β-disubstituted alcohols was achieved by the addition of an external hydrogen source to the reaction mixture.
Nickel-Catalyzed Alkylation of Ketone Enolates: Synthesis of Monoselective Linear Ketones
Das, Jagadish,Vellakkaran, Mari,Banerjee, Debasis
, p. 769 - 779 (2019/01/24)
Herein we have developed a Ni-catalyzed protocol for the synthesis of linear ketones. Aryl, alkyl, and heteroaryl ketones as well as alcohols yielded the monoselective ketones in up to 90% yield. The catalytic protocol was successfully applied in to a gram-scale synthesis. For a practical utility, applications of a steroid derivative, oleyl alcohol, and naproxen alcohol were employed. Preliminary catalytic investigations involving the isolation of a Ni intermediate and defined Ni-H species as well as a series of deuterium-labeling experiments were performed.
Piano-stool Ru (II) arene complexes that contain ethylenediamine and application in alpha-alkylation reaction of ketones with alcohols
Kavukcu, Serdar Bat?kan,Günnaz, Salih,?ahin, Onur,Türkmen, Hayati
, (2019/03/21)
A series of piano-stool Ru (II) complexes (Ru1–7) bearing ethylenediamine with aryl and aliphatic groups were prepared and fully characterized by 1H, 13C, 19F and 31P NMR spectroscopy, FT-IR and elemental analysis. The crystal structures of Ru2–4 and Ru7 were determined by X-ray crystallography. They were successfully applied to the alpha(α)-alkylation of aliphatic and aromatic ketones with alcohols via the borrowing hydrogen strategy in mild reaction conditions within a short time. The catalytic system has a broad substrate scope, which allows the synthesis of alpha alkylated ketones with excellent yields. The electronic and steric effects of complexes on catalytic activity were analysed. The influence of the carbon chain length of the ligand on the alpha-alkylation reaction of ketones was also investigated. The catalytic cycle was also examined by 1H-NMR spectroscopy in d8-toluene.
2-Methyltetrahydrofuran (2-MeTHF): A Green Solvent for Pd?NHC-Catalyzed Amide and Ester Suzuki-Miyaura Cross-Coupling by N?C/O?C Cleavage
Lei, Peng,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
supporting information, p. 5654 - 5660 (2019/11/16)
The palladium-NHC-catalyzed (NHC=N-heterocyclic carbene) Suzuki-Miyaura cross-coupling of amides and esters via highly chemoselective N?C(O) and O?C(O) cleavage with aryl boronic acids using green, sustainable and eco-friendly 2-methyltetrahydrofuran (2-MeTHF) is reported. A variety of amides and aryl esters were coupled with aryl boronic acids in high to excellent yields. This method employs commercially-available, air- and moisture-stable Pd(II) ?NHC precatalysts. Crucially, the use of 2-MeTHF leads to the highest TON reported to date in amide N?C(O) bond cross-coupling. This operationally-simple protocol was utilized in the synthesis a bioactive ketone intermediate, emphasizing the potential of 2-MeTHF as a green solvent in unconventional amide bond disconnection. Given the tremendous importance of amide bond cross-coupling strategies and the drive to maintain full sustainability in cross-coupling processes, we expect that the synthetic method will be of broad interest.
