4613-11-0Relevant articles and documents
Reactive separation of β-bromoethylbenzene from α-β-bromoethylbenzene mixtures: a Zn2+-mediated radical polymerization mechanism
Deng, Tianyu,Tian, Jiaming,Yan, Binhang,Zhu, Junqiu
, p. 1219 - 1222 (2022/02/03)
A Zn2+-induced reactive separation method for the purification of β-bromoethylbenzene from α-β-bromoethylbenzene mixtures is discovered, where the selective decomposition of α-bromoethylbenzene follows a radical mechanism. Zn2+ facilitates the homolysis of the C-Br bond of halohydrocarbons with benzyl bromide, enabling the separation of the corresponding isomers with almost identical physical properties.
Decatungstate Catalyzed Synthesis of Trifluoromethylthioesters from Aldehydes via a Radical Process
Ye, Zhegao,Lei, Ziran,Ye, Xiaodong,Zhou, Liejin,Wang, Yanan,Yuan, Zheliang,Gao, Feng,Britton, Robert
supporting information, p. 765 - 775 (2021/12/17)
Here we report a mild and general method for the trifluoromethylthiolation of aldehydes using N-trifluoromethylthiosaccharin as the CF3S radical source and sodium decatungstate (NaDT) as the photocatalyst. This reaction proceeds via hydrogen at
Decarboxylative cross-nucleophile coupling via ligand-to-metal charge transfer photoexcitation of Cu(ii) carboxylates
Li, Qi Yukki,Gockel, Samuel N.,Lutovsky, Grace A.,DeGlopper, Kimberly S.,Baldwin, Neil J.,Bundesmann, Mark W.,Tucker, Joseph W.,Bagley, Scott W.,Yoon, Tehshik P.
, p. 94 - 99 (2022/01/11)
Reactions that enable carbon–nitrogen, carbon–oxygen and carbon–carbon bond formation lie at the heart of synthetic chemistry. However, substrate prefunctionalization is often needed to effect such transformations without forcing reaction conditions. The development of direct coupling methods for abundant feedstock chemicals is therefore highly desirable for the rapid construction of complex molecular scaffolds. Here we report a copper-mediated, net-oxidative decarboxylative coupling of carboxylic acids with diverse nucleophiles under visible-light irradiation. Preliminary mechanistic studies suggest that the relevant chromophore in this reaction is a Cu(ii) carboxylate species assembled in situ. We propose that visible-light excitation to a ligand-to-metal charge transfer (LMCT) state results in a radical decarboxylation process that initiates the oxidative cross-coupling. The reaction is applicable to a wide variety of coupling partners, including complex drug molecules, suggesting that this strategy for cross-nucleophile coupling would facilitate rapid compound library synthesis for the discovery of new pharmaceutical agents. [Figure not available: see fulltext.].
Selective C(sp3)?N Bond Cleavage of N,N-Dialkyl Tertiary Amines with the Loss of a Large Alkyl Group via an SN1 Pathway
Bai, Lu,Li, Linqiang,Liu, Mengtian,Luan, Xinjun,Wu, Jiaoyu
supporting information, (2021/12/01)
Polar disconnection of the C(sp3)?N bond of N,N-dialkyl-substituted tertiary amines via ammonium species conventionally favored the loss of the smaller alkyl group by an SN2 displacement, while selective C(sp3)?N bond cleavage by cutting off the larger alkyl group is still underdeveloped. Herein, we present a novel Pd0-catalyzed [2+2+1] annulation, proceeding through an alkyne-directed palladacycle formation and consecutive diamination with a tertiary hydroxylamine by cleaving its N?O bond and one C(sp3)?N bond, for the rapid assembly of tricyclic indoles in a single-step transformation. Noteworthy, experimental results indicated that large tert-butyl and benzyl groups were selectively cleaved via an SN1 pathway, in the presence of a smaller alkyl group (Me, Et, iPr). Under the guidance of this new finding, tricyclic indoles bearing a removable alkyl group could be exclusively obtained by using a (α-methyl)benzyl/benzyl or tert-butyl/2-(methoxycarbonyl)ethyl mixed amino source.
Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals
Jiang, Huifang,Lu, Rui,Luo, Xiaolin,Si, Xiaoqin,Xu, Jie,Lu, Fang
supporting information, p. 1292 - 1296 (2020/12/09)
With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
Enantioselective Reductive Cross-Coupling of Aryl/Alkenyl Bromides with Benzylic Chlorides via Photoredox/Biimidazoline Nickel Dual Catalysis
Cheng, Xiaokai,Fang, Qun,Li, Tongtong,Lu, Jiamin,Lu, Zhan,Wang, Huifeng
supporting information, (2022/02/07)
The asymmetric reductive arylation and alkenylation of benzylic chloride under photoredox/nickel dual catalysis using chiral biimidazoline (BiIm) ligand is reported to access 1,1-diaryl alkanes and aryl allylic compounds with good yield as well as stereo-
Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
supporting information, p. 16470 - 16485 (2021/10/20)
The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
Reactivity of (bi-Oxazoline)organonickel Complexes and Revision of a Catalytic Mechanism
Ju, Luchuan,Lin, Qiao,LiBretto, Nicole J.,Wagner, Clifton L.,Hu, Chunhua Tony,Miller, Jeffrey T.,Diao, Tianning
, p. 14458 - 14463 (2021/09/18)
Bi-Oxazoline (biOx) has emerged as an effective ligand framework for promoting nickel-catalyzed cross-coupling, cross-electrophile coupling, and photoredox-nickel dual catalytic reactions. This report fills the knowledge gap of the organometallic reactivity of (biOx)Ni complexes, including catalyst reduction, oxidative electrophile activation, radical capture, and reductive elimination. The biOx ligand displays no redox activity in (biOx)Ni(I) complexes, in contrast to other chelating imine and oxazoline ligands. The lack of ligand redox activity results in more negative reduction potentials of (biOx)Ni(II) complexes and accounts for the inability of zinc and manganese to reduce (biOx)Ni(II) species. On the basis of these results, we revise the formerly proposed “sequential reduction” mechanism of a (biOx)Ni-catalyzed cross-electrophile coupling reaction by excluding catalyst reduction steps.
Iron-catalysed enantioconvergent Suzuki-Miyaura cross-coupling to afford enantioenriched 1,1-diarylalkanes
Tyrol, Chet C.,Yone, Nang S.,Gallin, Connor F.,Byers, Jeffery A.
, p. 14661 - 14664 (2020/12/02)
The first stereoconvergent Suzuki-Miyaura cross-coupling reaction was developed to afford enantioenriched 1,1-diarylalkanes. An iron-based complex containing a chiral cyanobis(oxazoline) ligand framework was best to obtain enantioenriched 1,1-diarylalkanes from cross-coupling reactions between unactivated aryl boronic esters and benzylic chlorides. Enhanced yields were obtained when 1,3,5-trimethoxybenzene was used as an additive, which is hypothesized to extend the lifetime of the iron-based catalyst. Exceptional enantioselectivities were obtained with challenging ortho-substituted benzylic chlorides. This journal is
Synthesis of dimeric molecules via ag-catalyzed electrochemical homocoupling of organic bromides paired with electrooxidation of urea
Klinkova, Anna,Krivoshapkina, Elena F.,Medvedev, Jury J.,Medvedeva, Xenia V.,Pivovarova, Yekaterina,Steksova, Yulia P.
, (2020/11/09)
We present a sacrificial anode-free approach to reductive homocoupling of organohalides that does not require a co-catalyst. In this approach, a divided electrochemical cell with aprotic and aqueous compartments separated by an anion exchange membrane enables coupling of the cathodic homocoupling reaction with anodic oxidation of urea. We show that, in contrast with traditional one-compartment cells relying on sacrificial anodes, the proposed cell configuration maintains stable cell voltage in the course of galvanostatic electrolysis. A synthetic potential of this method was assessed using a series of 13 organic bromides that demonstrated a strong dependence of the reaction outcome on the structure of the organic substrate, more specifically, the dissociation energy of the C–Br bond and the redox properties of formed radicals, which are discussed in detail. While not being suitable for the synthesis of byarylstructures, this method is excellent for C(sp3)-C(sp3) coupling to corresponding dimeric products with up to quantitative yields. Simultaneous electrochemical treatment of nitrogenous waste in the adjacent half-cell provides an additional incentive for wide adaptation of this sustainable synthetic approach.
