14315-12-9Relevant academic research and scientific papers
Cobalt-Catalyzed Suzuki Biaryl Coupling of Aryl Halides
Asghar, Soneela,Tailor, Sanita B.,Elorriaga, David,Bedford, Robin B.
, (2017)
Readily accessed cobalt pre-catalysts with N-heterocyclic carbene ligands catalyze the Suzuki cross-coupling of aryl chlorides and bromides with alkyllithium-activated arylboronic pinacolate esters. Preliminary mechanistic studies indicate that the cobalt
A mild and ligand-free Ni-catalyzed silylation via C-OMe cleavage
Zarate, Cayetana,Nakajima, Masaki,Martin, Ruben
, p. 1191 - 1197 (2017)
Metal-catalyzed transformations that forge carbon-heteroatom bonds are of central importance in organic synthesis. Despite the formidable potential of aryl methyl ethers as coupling partners, the scarcity of metal-catalyzed C-heteroatom bond formations via C-OMe cleavage is striking, with isolated precedents requiring specialized, yet expensive, ligands, high temperatures, and π-extended backbones. We report an unprecedented catalytic ipso-silylation of aryl methyl ethers under mild conditions and without recourse to external ligands. The method is distinguished by its wide scope, which includes the use of benzyl methyl ethers, vinyl methyl ethers, and unbiased anisóle derivatives, thus representing a significant step forward for designing new C-heteroatom bond formations via C-OMe scission. Applications of this transformation in orthogonal silylation techniques as well as in further derivatizations are also described. Preliminary mechanistic experiments suggest the intermediacy of Ni(0)-ate complexes, leaving some doubt that a canonical catalytic cycle consisting of an initial oxidative addition of the C-OMe bond to Ni(0) species comes into play.
Room Temperature C-H Arylation of Benzofurans by Aryl Iodides
Mayhugh, Amy L.,Luscombe, Christine K.
supporting information, p. 7079 - 7082 (2021/09/18)
A robust method of room temperature direct arylation for benzofuran is reported. This discovery allows for mild arylation by commercially available aryl iodides with complete C-2 regioselectivity and tolerates a range of functional groups, including heat sensitive groups. Mechanistically, a Heck-type oxyarylation product from a direct arylation process is reported as a key piece of evidence for a carbopalladation intermediate.
Tris-NHC-propagated self-supported polymer-based Pd catalysts for heterogeneous C-H functionalization
Choudhury, Joyanta,Dutta, Tapas Kumar,Mandal, Tanmoy,Mohanty, Sunit
supporting information, p. 10182 - 10185 (2021/10/12)
Three-dimensionally propagated imidazolium-containing mesoporous coordination polymer and organic polymer-based platforms were successfully exploited to develop single-site heterogenized Pd-NHC catalysts for oxidative arene/heteroarene C-H functionalization reactions. The catalysts were efficient in directed arene halogenation, and nondirected arene and heteroarene arylation reactions. High catalytic activity, excellent heterogeneity and recyclability were offered by these systems making them promising candidates in the area of heterogeneous C-H functionalization, where efficient catalysts are still scarce.
Nickel-Catalyzed Asymmetric Hydrogenation of Cyclic Alkenyl Sulfones, Benzo[ b]thiophene 1,1-Dioxides, with Mechanistic Studies
Liu, Gongyi,Tian, Kui,Li, Chenzong,You, Cai,Tan, Xuefeng,Zhang, Heng,Zhang, Xumu,Dong, Xiu-Qin
supporting information, p. 668 - 675 (2021/02/06)
A highly efficient catalytic system based on the cheap transition metal nickel for the asymmetric hydrogenation of challenging cyclic alkenyl sulfones, 3-substituted benzo[b]thiophene 1,1-dioxides, was first successfully developed. A series of hydrogenation products, chiral 2,3-dihydrobenzo[b]thiophene 1,1-dioxides, were obtained in high yields (95-99%) with excellent enantioselectivities (90-99% ee). According to the results of nonlinear effect studies, deuterium-labeling experiments, and DFT calculation investigations, a reasonable catalytic mechanism for this nickel-catalyzed asymmetric hydrogenation was provided, which displayed that the two added hydrogen atoms of the hydrogenation products could be from H2 through the insertion of Ni-H and subsequent hydrogenolysis.
Chiral Benzothiophene Synthesis via Enantiospecific Coupling of Benzothiophene S-Oxides with Boronic Esters
Aggarwal, Varinder K.,Noble, Adam,Sang, Ruocheng
supporting information, p. 25313 - 25317 (2021/11/09)
Benzothiophenes are valuable heterocycles that are widely used in medicines, agrochemicals, and materials science. Herein, we report a general method for the synthesis of enantioenriched 2,3-disubstituted benzothiophenes via a transition-metal-free C2-alkylation of benzothiophenes with boronic esters. The reactions utilize benzothiophene S-oxides in lithiation-borylations to generate intermediate arylboronate complexes, and subsequent Tf2O-promoted S?O bond cleavage to trigger a Pummerer-type 1,2-metalate shift, which gives the coupled products with complete enantiospecificity. Primary, secondary and tertiary alkyl boronic esters and aryl boronic esters are successfully coupled with a range of C3-substituted benzothiophenes. Importantly, this transformation does not require the use of C3 directing groups, therefore it overcomes a major limitation of previously developed transition-metal-mediated C2 alkylations of benzothiophenes.
C3-Arylation of indoles with aryl ketonesviaC-C/C-H activations
Dai, Hui-Xiong,Guo, Zi-Qiong,Ma, Biao,Wang, Xing,Wang, Zhen-Yu,Xu, Hui
supporting information, p. 9716 - 9719 (2021/09/30)
C3-Arylation of indoles with aryl ketones is accomplishedviapalladium-catalyzed ligand-promoted Ar-C(O) cleavage and subsequent C-H arylation of indole. Various (hetero)aryl ketones are compatible in this reaction, affording the corresponding 3-arylindoles in moderate to good yields. Further introduction of an indole moiety into the natural products desoxyestrone and evodiamine demonstrate the synthetic utility of this protocol.
Infrared Irradiation-Assisted Solvent-Free Pd-Catalyzed (Hetero)aryl-aryl Coupling via C?H Bond Activation
Albano, Gianluigi,Decandia, Gianfranco,Capozzi, Maria Annunziata M.,Zappimbulso, Nicola,Punzi, Angela,Farinola, Gianluca M.
, p. 3391 - 3401 (2021/07/28)
The increasing attention towards environmentally friendly synthetic protocols has boosted studies directed to the development of green and sustainable methods for direct C?H bond arylation of (hetero)arenes. In this context, here the infrared (IR) irradia
Synthesis of benzofurans from the cyclodehydration of α-phenoxy ketones mediated by Eaton’s reagent
Ma, Lin,Ma, Zhanwei,Zhang, Min,Zhou, Min
, p. 426 - 436 (2020/03/23)
Cyclodehydration of α-phenoxy ketones promoted by Eaton’s reagent (phosphorus pentoxide–methanesulfonic acid) is used to prepare 3-substituted or 2,3-disubstituted benzofurans with moderate to excellent yields under mild conditions. The method provides a facile access to benzofurans from readily available starting materials such as phenols and α-bromo ketones. The reaction is highly efficient, which is attributed to the good reactivity and fluidity of Eaton’s reagent. The reaction can be applied to prepare naphthofurans, furanocoumarins, benzothiophenes, and benzopyrans.
Characterization of heterogeneous aryl-Pd(ii)-oxo clusters as active species for C-H arylation
Shin, Taeil,Kim, Minjun,Jung, Younjae,Cho, Sung June,Kim, Hyunwoo,Song, Hyunjoon
supporting information, p. 14404 - 14407 (2020/12/01)
C-H arylation with heterogeneous palladium was investigated. The surface oxidation of Pd nanoparticles with a hypervalent iodine reagent, [Ph2I]BF4, resulted in the generation of Pd(ii)-aryl-oxo clusters, which were characterized as the crucial intermediate.
