24758-49-4Relevant academic research and scientific papers
Synthesis of biaryl ketones by arylation of Weinreb amides with functionalized Grignard reagents under thermodynamic controlvs.kinetic control ofN,N-Boc2-amides
Li, Guangchen,Szostak, Michal
supporting information, p. 3827 - 3831 (2020/06/03)
A highly efficient method for chemoselective synthesis of biaryl ketones by arylation of Weinreb amides (N-methoxy-N-methylamides) with functionalized Grignard reagents is reported. This protocol offers rapid entry to functionalized biaryl ketones after Mg/halide exchange with i-PrMgCl·LiCl under operationally-simple and practical reaction conditions. The scope of the method is highlighted in >40 examples, including bioactive compounds and pharmaceutical derivatives. Collectively, this transition-metal-free approach offers a major advantage over the recently established cross-coupling of amides by oxidative addition of N-C(O) bonds. Considering the utility of amide acylation reactions in modern synthesis, we expect that this method will be of broad interest.
Nickel-Catalyzed Decarbonylative Amination of Carboxylic Acid Esters
Malapit, Christian A.,Borrell, Margarida,Milbauer, Michael W.,Brigham, Conor E.,Sanford, Melanie S.
supporting information, p. 5918 - 5923 (2020/04/08)
The reaction of carboxylic acid derivatives with amines to form amide bonds has been the most widely used transformation in organic synthesis over the past century. Its utility is driven by the broad availability of the starting materials as well as the kinetic and thermodynamic driving force for amide bond formation. As such, the invention of new reactions between carboxylic acid derivatives and amines that strategically deviate from amide bond formation remains both a challenge and an opportunity for synthetic chemists. This report describes the development of a nickel-catalyzed decarbonylative reaction that couples (hetero)aromatic esters with a broad scope of amines to form (hetero)aryl amine products. The successful realization of this transformation was predicated on strategic design of the cross-coupling partners (phenol esters and silyl amines) to preclude conventional reactivity that forms inert amide byproducts.
Kinetically Controlled, Highly Chemoselective Acylation of Functionalized Grignard Reagents with Amides by N?C Cleavage
Li, Guangchen,Szostak, Michal
supporting information, p. 611 - 615 (2020/01/02)
The direct transition-metal-free acylation of amides with functionalized Grignard reagents by highly chemoselective N?C cleavage under kinetic control has been accomplished. The method offers rapid and convergent access to functionalized biaryl ketones through transient tetrahedral intermediates. The direct access to functionalized Grignard reagents by in situ halogen–magnesium exchange promoted by the versatile turbo-Grignard reagent (iPrMgCl?LiCl) permits excellent substrate scope with respect to both the amide and Grignard coupling partners. These reactions enable facile, operationally simple and chemoselective access to tetrahedral intermediates from amides under significantly milder conditions than chelation-controlled intermediates. This novel direct two-component coupling sets the stage for using amides as acylating reagents in an alternative paradigm to the metal-chelated approach, acyl metals and Weinreb amides.
One-pot, modular approach to functionalized ketones via nucleophilic addition/Buchwald-Hartwig amination strategy
De Jong, Jorn,Heijnen, Dorus,Helbert, Hugo,Feringa, Ben L.
supporting information, p. 2908 - 2911 (2019/03/17)
A general one-pot procedure for the 1,2-addition of organolithium reagents to amides followed by the Buchwald-Hartwig amination with in situ released lithium amides is presented. In this work amides are used as masked ketones, revealed by the addition of organolithium reagents which generates a lithium amide, suitable for subsequent Buchwald-Hartwig coupling in the presence of a palladium catalyst. This methodology allows for rapid, efficient and atom economic synthesis of aminoarylketones in good yields.
Ni(i)-Ni(iii) cycle in Buchwald-Hartwig amination of aryl bromide mediated by NHC-ligated Ni(i) complexes
Inatomi, Takahiro,Fukahori, Yukino,Yamada, Yuji,Ishikawa, Ryuta,Kanegawa, Shinji,Koga, Yuji,Matsubara, Kouki
, p. 1784 - 1793 (2019/04/29)
Intermediate amide complexes of NHC-ligated monovalent nickel in Buchwald-Hartwig amination of aryl halides were isolated and structurally characterized. The amide complexes reacted with aryl bromide to form a cross-coupling product. Lowerature observation of the oxidative addition product of the Ni(i) amide complex with aryl bromide indicated the presence of a Ni(iii) intermediate. The results showed that a well-defined mononuclear NHC-Ni(i) complex can act as a key intermediate in homogeneous catalysis.
NIXANTPHOS: A highly active ligand for palladium catalyzed Buchwald-Hartwig amination of unactivated aryl chlorides
Mao, Jianyou,Zhang, Jiadi,Zhang, Shuguang,Walsh, Patrick J.
supporting information, p. 8690 - 8696 (2018/07/13)
Xantphos is one of the two most common ligands used in palladium catalyzed Buchwald-Hartwig amination reactions, because of its broad scope and high probability of success. It does not, however, work well with unactivated aryl chlorides. Herein NIXANTPHOS is compared to Xantphos and an array of mono- and bidentate phosphines. NIXANTPHOS outperforms Xantphos and all other bidentate ligands examined. Under the optimal reaction conditions, unactivated aryl chlorides afford the expected products in good to excellent yield with as low as 0.05 mol% (500 ppm) palladium loading.
Ni/Ti Dual Catalytic Cross-Coupling of Nitriles and Organobromides to Access Ketones
Chenniappan, Vinoth Kumar,Silwal, Sajan,Rahaim, Ronald J.
, p. 4539 - 4544 (2018/05/23)
Herein, we report the development of a dual catalytic approach for the cross-coupling of nitriles with aryl- and aliphatic-bromides. A titanium(III) catalyst is used to activate nitriles enabling their coupling with organobromides through a nickel catalyst. The Ni/Ti system efficiently prepared unsymmetrical ketones with good chemoselectivity and could selectively couple a bromide in the presence of other functionalizable handles.
A General Palladium–Phosphine Complex To Explore Aryl Tosylates in the N-Arylation of Amines: Scope and Limitations
Choy, Pui Ying,Chung, Kin Ho,Yang, Qingjing,So, Chau Ming,Sun, Raymond Wai-Yin,Kwong, Fuk Yee
supporting information, p. 2465 - 2474 (2018/09/10)
The scope and limitations of the monoselective N-arylation of various amines by using aryl and hetaryl tosylates are presented. The air-stable and easily accessible Pd(OAc)2/CM-phos {CM-phos=2-[2-(dicyclohexylphosphino)phenyl]-1-methyl-1H-indole}catalyst system was able to deal with a wide range of aryl tosylate substrates as well as amine nucleophiles, including primary and secondary cyclic/acyclic aliphatic amines and anilines. NH-Bearing heterocycles such as indole, carbazole, pyrrole, 10-phenothiazine, and 10-phenoxazine were shown to be feasible coupling partners under this catalytic system. The described reaction conditions tolerate a wide range of functional groups and allow an array of aromatic amines as well as unsymmetrical amine products to be easily accessed from the various phenolic derivatives. Interestingly, this catalyst system even offers the opportunity to perform the reaction in water medium. We also report the intermolecular coupling of optically active α-central chiral amines with aryl tosylates without erosion of the enantiomeric purity.
Nickel-Catalyzed Amination of Aryl 2-Pyridyl Ethers via Cleavage of the Carbon-Oxygen Bond
Li, Jing,Wang, Zhong-Xia
supporting information, p. 3723 - 3726 (2017/07/26)
Reaction of aryl 2-pyridyl ethers with amines was carried out via Ni-catalyzed C-OPy bond cleavage, giving aniline derivatives in reasonable to excellent yields. Both electron-rich and electron-poor aryl 2-pyridyl ethers and a wide range of amines can be used in the transformation. The method provides a conversion way for the 2-pyridyloxy directing group in the C-H bond functionalization reactions.
Arylation of Amines in Alkane Solvents by using Well-Defined Palladium-N-Heterocyclic Carbene Complexes
Marelli, Enrico,Chartoire, Anthony,Le Duc, Gaetan,Nolan, Steven P.
, p. 4021 - 4024 (2015/12/26)
The use of the ITent-based series of Pd-N-heterocyclic carbenes precatalysts (Tent= Tentacular) enables the Buchwald-Hartwig amine arylation reaction in apolar alkane solvents. The use of such solvents is rare because of their poor solvation properties. Nonetheless, they could be of interest for industrial applications, as they can be disposed of in an energetically favorable manner and may potentially simplify product isolation. The excellent solubility of the precatalysts permitted the desired products to be obtained in yields ranging from 75 to 96 %, even with deactivated and functionalized coupling partners. Fueling cross-couplings: The use of ITent-based Pd precatalysts (Tent=tentacular) enables the Buchwald-Hartwig amine arylation reaction in alkane solvents. Such solvents could be of interest for industrial applications, as they can be disposed of in an energetically favorable manner and may potentially simplify product isolation. Yields ranging from 75 to 96 % are obtained, even with challenging substrates.
