- Selective Benzylic CH-Borylations by Tandem Cobalt Catalysis
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Metal-catalyzed C?H activations are environmentally and economically attractive synthetic strategies for the construction of functional molecules as they obviate the need for pre-functionalized substrates and minimize waste generation. Great challenges reside in the control of selectivities, the utilization of unbiased hydrocarbons, and the operation of atom-economical dehydrocoupling mechanisms. An especially mild borylation of benzylic CH bonds was developed with the ligand-free pre-catalyst Co[N(SiMe3)2]2 and the bench-stable and inexpensive borylation reagent B2pin2 that produces H2 as the only by-product. A full set of kinetic, spectroscopic, and preparative mechanistic studies are indicative of a tandem catalysis mechanism of CH-borylation and dehydrocoupling via molecular CoI catalysts.
- Bauer, Matthias,Ghosh, Pradip,Jacobi von Wangelin, Axel,Schoch, Roland
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- Cu-mediated: vs. Cu-free selective borylation of aryl alkyl sulfones
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A Cu-catalysed borylation of aryl alkyl sulfones was developed for the high yield synthesis of versatile arylboronic esters using a readily prepared NHC-Cu catalyst. In addition, the selective cleavage of either alkyl(C)-sulfonyl or aryl(C)-sulfonyl bonds
- Hu, Jiefeng,Huang, Mingming,Marder, Todd B.,Radius, Udo,Tang, Man,Westcott, Stephen A.
-
supporting information
p. 395 - 398
(2022/01/19)
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- Nickel-Catalyzed Ipso-Borylation of Silyloxyarenes via C-O Bond Activation
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The conversion of silyloxyarenes to boronic acid pinacol esters via nickel catalysis is described. In contrast to other borylation protocols of inert C-O bonds, the method is competent in activating the carbon-oxygen bond of silyloxyarenes in isolated aromatic systems lacking a directing group. The catalytic functionalization of benzyl silyl ethers was also achieved under these conditions. Sequential cross-coupling reactions were achieved by leveraging the orthogonal reactivity of silyloxyarenes, which could then be functionalized subsequently.
- Pein, Wesley L.,Wiensch, Eric M.,Montgomery, John
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supporting information
(2021/06/28)
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- Arene borylation through C–H activation using Cu3(BTC)2 as heterogeneous catalyst
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C–H borylation by diborane is an important process to access organoboron compounds. Noble metals, including Ir and Rh-based complexes either in the form of homogeneous or heterogeneous catalysts, have been reported to promote arene C–H borylation. Recently, metal organic frameworks (MOFs) having Ir and Co as active sites have been used as catalysts, but they require co-catalysts. In the present study, commercially available Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylate) MOF is reported as an effective catalyst to promote borylation of arenes through C–H activation employing bis(pinacolato)diboron (1) as reagent leading to benzylic and aromatic borylation products. Interestingly, other related MOFs like MIL-101(Cr) and Al(OH)(BDC) (BDC: 1,4-benzenedicarboxylate) do not exhibit catalytic activity under identical conditions. Mechanistic studies using in-situ IR spectroscopy reveal that Cu ions play a crucial role in activating the arene and B–B bond in 1.
- Dhakshinamoorthy, Amarajothi,García, Cristina Vallés,Concepcion, Patricia,Garcia, Hermenegildo
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p. 212 - 217
(2020/07/06)
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- C(sp3)-H selective benzylic borylation by in situ reduced ultrasmall Ni species on CeO2
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Herein, we report that highly dispersed Ni hydroxide species supported on CeO2 act as an efficient heterogeneous catalyst for the selective borylation of benzylic C(sp3)-H bonds of alkylarenes including secondary derivatives, using pinacolborane as the bo
- Yoshii, Daichi,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
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p. 2150 - 2155
(2021/02/20)
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- Evaluation of the role of graphene-based Cu(i) catalysts in borylation reactions
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Carbon-supported catalysts have been considered as macromolecular ligands which modulate the activity of the metallic catalytic center. Understanding the properties and the factors that control the interactions between the metal and support allows a fine tuning of the catalyzed processes. Although huge effort has been devoted to comprehending binding energies and charge transfer for single atom noble metals, the interaction of graphenic surfaces with cheap and versatile Cu(i) salts has been scarcely studied. A methodical experimental and theoretical analysis of different carbon-based Cu(i) materials in the context of the development of an efficient, general, scalable, and sustainable borylation reaction of aliphatic and aromatic halides has been performed. We have also examined the effect of microwave (MW) radiation in the preparation of these type of materials using sustainable graphite nanoplatelets (GNP) as a support. A detailed analysis of all the possible species in solution revealed that the catalysis is mainly due to an interesting synergetic Cu2O/graphene performance, which has been corroborated by an extensive theoretical study. We demonstrated through DFT calculations at a high level of theory that graphene enhances the reactivity of the metal in Cu2O against the halide derivative favoring a radical departure from the halogen. Moreover, this material is able to stabilize radical intermediates providing unexpected pathways not observed using homogeneous Cu(i) catalysed reactions. Finally, we proved that other common carbon-based supports like carbon black, graphene oxide and reduced graphene oxide provided poorer results in the borylation process.
- Cid, M. B.,Díaz, Cristina,Franco, Mario,Lamsabhi, Al Mokhtar,Sainz, Raquel,Tortosa, Mariola
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p. 3501 - 3513
(2021/06/06)
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- Visible-light-driven graphene supported Cu/Pd alloy nanoparticle-catalyzed borylation of alkyl bromides and chlorides in air
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A highly efficient photocatalytic protocol for borylation of alkyl bromides and chlorides with graphene supported Cu/Pd alloy nanoparticles as a heterogeneous catalyst is reported. This photocatalytic system operates with visible light in air, providing a wide range of primary and secondary alkyl halides with B2pin2 or B2neop2 in high yields at low temperatures, thereby demonstrating its broad utility and functional group tolerance. The high performance is attributed to a synergistic effect of localized surface plasmon resonance (LSPR) of Cu and charge transfer from Cu to Pd due to the alloy surface charge heterogeneity. Transfer of energetic electrons from Pd to electrophilic alkyl halides lead to the formation of the alkyl radicals, which quickly react with a nucleophilic adduct of a diboron compound with base adsorbed on the positively charged Cu sites to form the corresponding borylation product.
- Jiao, Zhi-Feng,Tian, Ya-Ming,Guo, Xiao-Ning,Radius, Udo,Braunschweig, Holger,Marder, Todd B.,Guo, Xiang-Yun
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p. 258 - 265
(2021/02/16)
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- Photochemical Radical C–H Halogenation of Benzyl N-Methyliminodiacetyl (MIDA) Boronates: Synthesis of α-Functionalized Alkyl Boronates
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α-Haloboronates are useful organic synthons that can be converted to a diverse array of α-substituted alkyl borons. Methods to α-haloboronates are limiting and often suffer from harsh reaction conditions. Reported herein is a photochemical radical C-H halogenation of benzyl N-methyliminodiacetyl (MIDA) boronates. Fluorination, chlorination, and bromination reactions were effective by using this protocol. Upon reaction with different nucleophiles, the C?Br bond in the brominated product could be readily transformed to a series of C?C, C?O, C?N, C?S, C?P, and C?I bonds, some of which are difficult to forge with α-halo sp2-B boronate esters. An activation effect of B(MIDA) moiety was found.
- Yang, Ling,Tan, Dong-Hang,Fan, Wen-Xin,Liu, Xu-Ge,Wu, Jia-Qiang,Huang, Zhi-Shu,Li, Qingjiang,Wang, Honggen
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supporting information
p. 3454 - 3458
(2020/12/17)
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- Structure-Based Optimization and Discovery of M3258, a Specific Inhibitor of the Immunoproteasome Subunit LMP7 (β5i)
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Proteasomes are broadly expressed key components of the ubiquitin-dependent protein degradation pathway containing catalytically active subunits (β1, β2, and β5). LMP7 (β5i) is a subunit of the immunoproteasome, an inducible isoform that is predominantly expressed in hematopoietic cells. Clinically effective pan-proteasome inhibitors for the treatment of multiple myeloma (MM) nonselectively target LMP7 and other subunits of the constitutive proteasome and immunoproteasome with comparable potency, which can limit the therapeutic applicability of these drugs. Here, we describe the discovery and structure-based hit optimization of novel amido boronic acids, which selectively inhibit LMP7 while sparing all other subunits. The exploitation of structural differences between the proteasome subunits culminated in the identification of the highly potent, exquisitely selective, and orally available LMP7 inhibitor 50 (M3258). Based on the strong antitumor activity observed with M3258 in MM models and a favorable preclinical data package, a phase I clinical trial was initiated in relapsed/refractory MM patients.
- Klein, Markus,Busch, Michael,Friese-Hamim, Manja,Crosignani, Stefano,Fuchss, Thomas,Musil, Djordje,Rohdich, Felix,Sanderson, Michael P.,Seenisamy, Jeyaprakashnarayanan,Walter-Bausch, Gina,Zanelli, Ugo,Hewitt, Philip,Esdar, Christina,Schadt, Oliver
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p. 10230 - 10245
(2021/07/26)
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- The functionalization of benzene by boranes using trispyrazolylborate complexes
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The catalytic C[sbnd]H activation and borylation of arenes by trispyrazolylborate complexes is reported. Trispyrazolylborate rhodium and iridium complexes have been previously shown to activate a variety of C[sbnd]H bonds. Here, we show the catalytic borylation of arenes by the trispyrazolylborate ethylene complexes Tp'Rh(C2H4)2, and Tp'Ir(C2H4)2.
- Vetter, Andrew J.,DiBenedetto, Tarah A.,Ritz, Mikhaila D.,Jones, William D.
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- Carbon-carbon bond activation by B(OMe)3/B2pin2-mediated fragmentation borylation
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Selective carbon-carbon bond activation is important in chemical industry and fundamental organic synthesis, but remains challenging. In this study, non-polar unstrained Csp2-Csp3 and Csp2-Csp2 bond activation was achieved by B(OMe)3/B2pin2-mediated fragmentation borylation. Various indole derivatives underwent C2-regioselective C-C bond activation to afford two C-B bonds under transition-metal-free conditions. Preliminary mechanistic investigations suggested that C-B bond formation and C-C bond cleavage probably occurred in a concerted process. This new reaction mode will stimulate the development of reactions based on inert C-C bond activation. This journal is
- Chen, Quan,Jiang, Jiachen,Wang, Li,Wu, Aizhen,Yin, Youzhi,Zhang, Hua,Zhang, Ke,Zhao, Mengzhen,Zhong, Qi,Zou, Youliang
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p. 15104 - 15109
(2021/12/09)
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- Photoinduced NaI-Promoted Radical Borylation of Alkyl Halides and Pseudohalides
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A method for photoinduced NaI-promoted radical borylation of aliphatic halides and pseudohalides with bis(catecholato)diboron (B2cat2) as the boron source is introduced. The borylation reaction is operationally simple and shows high
- Wang, Chenglan,Zhou, Lu,Yang, Kai,Zhang, Feng,Song, Qiuling
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p. 1825 - 1830
(2021/05/28)
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- (o-Phenylenediamino)borylstannanes: Efficient Reagents for Borylation of Various Alkyl Radical Precursors
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(o-Phenylenediamino)borylstannanes were newly synthesized to achieve radical boryl substitutions of a variety of alkyl radical precursors. Dehalogenative, deaminative, decharcogenative, and decarboxylative borylations proceeded in the presence of a radica
- Suzuki, Kensuke,Nishimoto, Yoshihiro,Yasuda, Makoto
-
supporting information
p. 3968 - 3973
(2020/12/30)
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- Practical Synthesis of Allyl, Allenyl, and Benzyl Boronates through SN1′-Type Borylation under Heterogeneous Gold Catalysis
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Efficient borylation of sp3 C-O bonds by supported Au catalysts is described. Au nanoparticles supported on TiO2 showed high activity under mild conditions employing low catalyst loading conditions without the aid of any additives, such as phosphine and bases. A variety of allyl, propargyl, and benzyl substrates participated in the heterogeneously catalyzed reactions to furnish the corresponding allyl, allenyl, and benzyl boronates in high yields. Besides, Au/TiO2 was also effective for the direct borylation of allylic and benzylic alcohols. A mechanistic investigation based on a Hammett study and control experiments revealed that sp3 C-O bond borylation over supported Au catalysts proceeded through SN1′-type mechanism involving the formation of a carbocationic intermediate. The high activity, reusability, and environmental compatibility of the supported Au catalysts as well as the scalability of the reaction system enable the practical synthesis of valuable organoboron compounds.
- Miura, Hiroki,Hachiya, Yuka,Nishio, Hidenori,Fukuta, Yohei,Toyomasu, Tomoya,Kobayashi, Kosa,Masaki, Yosuke,Shishido, Tetsuya
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p. 758 - 766
(2021/02/03)
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- Boronic acid derivatives
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The present invention relates to boronic acid derivatives; the present invention provides compounds of formula (I) or pharmaceutically acceptable salts, solvates, polymorphs or isomers thereof, pharmaceutical compositions comprising these compounds, and u
- -
-
Paragraph 0098; 0109-0112; 0203; 0214-0217
(2021/07/21)
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- Boronic acid derivatives
-
The present invention relates to boronic acid derivatives; the present invention provides compounds of formula (I) or pharmaceutically acceptable salts, solvates, polymorphs or isomers thereof, pharmaceutical compositions comprising these compounds, and uses of such compounds in the treatment of lmp7-related diseases.
- -
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Paragraph 0113; 0124-0127; 0302; 0305-0308
(2021/07/21)
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- Metal catalyst-free photo-induced alkyl C-O bond borylation
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Metal catalyst free, blue visible light-induced C-O bond borylation of unactivated tertiary alkyl methyl oxalates has been developed to furnish tertiary alkyl boronates. From the secondary alcohols activated with imidazolylthionyl, moderate yields of boronates were attained under standard photo-induced conditions. Preliminary mechanistic studies confirmed the involvement of a (DMF)2-B2cat2 adduct that weakly absorbs light at 437 nm so as to initiate a Bcat radical. A radical-chain process is proposed wherein the alkyl radical is engaged. This journal is
- Chen, Changzhou,Gong, Hegui,Lei, Chuanhu,Ma, Guobin,Talukdar, Sangita,Zhao, Xinluo
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p. 10219 - 10222
(2020/09/18)
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- Ketone Synthesis from Benzyldiboronates and Esters: Leveraging α-Boryl Carbanions for Carbon-Carbon Bond Formation
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An alkoxide-promoted method for the synthesis of ketones from readily available esters and benzyldiboronates is described. The synthetic method is compatible with a host of sterically differentiated alkyl groups, alkenes, acidic protons α to carbonyl groups, tertiary amides, and aryl rings having common organic functional groups. With esters bearing α-stereocenters, high enantiomeric excess was maintained during ketone formation, establishing minimal competing racemization by deprotonation. Monitoring the reaction between benzyldiboronate and LiOtBu in THF at 23 °C allowed for the identification of products arising from deborylation to form an α-boryl carbanion, deprotonation, and alkoxide addition to form an "-ate" complex. Addition of 4-trifluoromethylbenzoate to this mixture established the α-boryl carbanion as the intermediate responsible for C-C bond formation and ultimately ketone synthesis. Elucidation of the role of this intermediate leveraged additional bond-forming chemistry and enabled the one-pot synthesis of ketones with α-halogen atoms and quaternary centers with four-different carbon substituents.
- Lee, Boran,Chirik, Paul J.
-
supporting information
p. 2429 - 2437
(2020/03/03)
-
- Efficient synthesis of alkylboronic esters: Via magnetically recoverable copper nanoparticle-catalyzed borylation of alkyl chlorides and bromides
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We report a magnetically separable Cu nanocatalyst (Fe-DOPA-Cu) for the borylation of alkyl halides with alkoxy diboron reagents, providing alkylboronic esters in high yields, with broad functional group tolerance under mild reaction conditions. The procedure is also applicable to the borylation of benzyl chlorides and bromides. Radical clock experiments support a radical-mediated process. Easy recycling of the catalyst resulted in no significant loss of activity up to ten runs.
- Shegavi, Mahadev L.,Agarwal, Abhishek,Bose, Shubhankar Kumar
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supporting information
p. 2799 - 2803
(2020/06/17)
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- Metal-Free Direct Deoxygenative Borylation of Aldehydes and Ketones
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Direct conversion of aldehydes and ketones into alkylboronic esters via deoxygenative borylation represents an unknown yet highly desirable transformation. Herein, we present a one-step and metal-free method for carbonyl deoxy-borylation under mild conditions. A wide range of aromatic aldehydes and ketones are tolerated and successfully converted into the corresponding benzylboronates. By the same deoxygenation manifold with aliphatic aldehydes and ketones, we also enable a concise synthesis of 1,1,2-tris(boronates), a family of compounds that currently lack efficient synthetic methods. Given its simplicity and versatility, we expect that this novel borylation approach could show great promise in organoboron synthesis and inspire more carbonyl deoxygenative transformations in both academic and industrial settings.
- Huang, Chia-Yu,Li, Chao-Jun,Li, Jianbin,Qiu, Zihang,Wang, Haining
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p. 13011 - 13020
(2020/09/01)
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- Cobalt(I)-Catalyzed Borylation of Unactivated Alkyl Bromides and Chlorides
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A cobalt-complex-catalyzed borylation of a wide range of alkyl halides with a diboron reagent (B2pin2 or B2neop2) has been developed under mild reaction conditions, demonstrating the first cobalt-mediated cross-coupling with alkyl electrophiles. This protocol allows alkyl boronic esters to be accessed from alkyl halides, including alkyl chlorides, which were used rarely as coupling partners. Mechanistic studies reveal the possible involvement of an alkyl radical intermediate in this cobalt-mediated catalytic cycle.
- Geetharani, K.,Prasad, K. Sujit,Varghese, Dominic,Verma, Piyush Kumar
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supporting information
p. 1431 - 1436
(2020/03/13)
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- Photoinduced Radical Borylation of Alkyl Bromides Catalyzed by 4-Phenylpyridine
-
Utilizing pyridine catalysis, we developed a visible-light-induced transition-metal-free radical borylation reaction of unactivated alkyl bromides that features a broad substrate scope and mild reaction conditions. Mechanistic studies revealed a novel nucleophilic substitution/photoinduced radical formation pathway, which could be utilized to trigger a variety of radical processes.
- Zhang, Li,Wu, Zhong-Qian,Jiao, Lei
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supporting information
p. 2095 - 2099
(2019/12/24)
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- Regioselective α-benzylation of 3-iodoazetidine via Suzuki cross-coupling
-
An efficient protocol for the synthesis of α-benzyl azetidines starting from benzylboronic acid pinacol ester derivatives and 3-iodoazetidine was developed. A wide range of α-benzyl azetidine derivatives were obtained in moderate to good yields with high regioselectivity (>99%).
- Qiu, Zhenjiang,Zhu, Mingxiang,Zheng, Lu,Li, Jingya,Zou, Dapeng,Wu, Yangjie,Wu, Yusheng
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supporting information
p. 1321 - 1324
(2019/04/25)
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- Mercapto-amide boronic acid derivative and application thereof as MBL (metal beta-lactamase) and/or SBL (serine beta-lactamase) inhibitor
-
The invention provides a compound of a formula (I) shown in the specification, or a conformational isomer, or an optical isomer or a pharmaceutically acceptable salt thereof. The compound of the formula (I) shown in the specification has excellent broad-spectrum inhibitory activity on MBL (metal beta-lactamase) and/or SBL (serine beta-lactamase), and can be used for preparing MBL and/or SBL inhibitors. Moreover, the compound disclosed by the invention has excellent antibacterial activity on multiple drug-resistant bacteria and is capable of reversing drug resistance of carbapenem drug-resistant bacteria, and the antibacterial effect of the compound is prior to those of positive control products such as L-captopril and tazobactam. The compound disclosed by the invention has very great potential in preparation of MBL/SBL dual inhibitors and medicines reversing drug resistance of carbapenem drug-resistance bacteria.
- -
-
Paragraph 0070-0073
(2019/09/14)
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- Structure-based development of (1-(3′-Mercaptopropanamido)methyl)boronic Acid Derived Broad-Spectrum, Dual-Action Inhibitors of Metallo- And Serine-β-lactamases
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The emergence and spread of bacterial pathogens acquired metallo-β-lactamase (MBL) and serine-β-lactamase (SBL) medicated β-lactam resistance gives rise to an urgent need for the development of new dual-action MBL/SBL inhibitors. Application of a pharmacophore fusion strategy led to the identification of (2′S)-(1-(3′-mercapto-2′-methylpropanamido)methyl)boronic acid (MS01) as a new dual-action inhibitor, which manifests broad-spectrum inhibition to representative MBL/SBL enzymes, including the widespread VIM-2 and KPC-2. Guided by the VIM-2:MS01 and KPC-2:MS01 complex structures, further structural optimization yielded new, more potent dual-action inhibitors. Selectivity studies indicated that the inhibitors had no apparent inhibition to human angiotensin-converting enzyme-2 and showed selectivity across serine hydrolyases in E. coli and human HEK293T cells labeled by the activity-based probe TAMRA-FP. Moreover, the inhibitors displayed potentiation of meropenem efficacy against MBL- or SBL-positive clinical isolates without apparent cytotoxicity. This work will aid efforts to develop new types of clinically useful dual-action inhibitors targeting MBL/SBL enzymes.
- Wang, Yao-Ling,Liu, Sha,Yu, Zhu-Jun,Lei, Yuan,Huang, Meng-Yi,Yan, Yu-Hang,Ma, Qiang,Zheng, Yang,Deng, Hui,Sun, Ying,Wu, Chengyong,Yu, Yamei,Chen, Qiang,Wang, Zhenling,Wu, Yong,Li, Guo-Bo
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p. 7160 - 7184
(2019/08/28)
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- Pyridine-catalyzed desulfonative borylation of benzyl sulfones
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Herein, we report the transition-metal free, pyridine-catalyzed desulfonative borylation of benzyl sulfones with bis(pinacolato)diboron (B2pin2). A variety of benzhydryl- and benzyl boronic esters could be synthesized from readily prepared sulfone derivatives. The borylation of cyclic sulfones accompanied by ring opening also proceeded to afford the corresponding sulfonate, which could be converted into functionalized sulfones and sulfonamides.
- Maekawa, Yuuki,Ariki, Zachary T.,Nambo, Masakazu,Crudden, Cathleen M.
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supporting information
p. 7300 - 7303
(2019/08/15)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
- -
-
Paragraph 0238; 0243
(2019/01/07)
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- Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis
-
The alkynylbenziodoxole derivatives are recently developed alkynylation reagents in organic synthesis, which demonstrate excellent radical alkynylation reactivity in photoredox catalysis reactions. Herein we report the synthesis of alkynylbenziodoxole derivatives with difluoro, monofluoro, monomethoxy, and dimethoxy substitution on the benziodoxole moiety, and investigated their radical alkynylation reactivity for the first time. A series of mechanistic experiments were conducted to study the radical acceptor and oxidative quencher reactivity of alkynylbenziodoxoles, in which unsubstituted alkynylbenziodoxoles played balancing roles in both processes, while electron-rich benziodoxole derivatives demonstrate synthetic advantages in some cases.
- Pan, Yue,Jia, Kunfang,Chen, Yali,Chen, Yiyun
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supporting information
p. 1215 - 1221
(2018/06/13)
-
- Visible-Light-Mediated Aerobic Oxidation of Organoboron Compounds Using in Situ Generated Hydrogen Peroxide
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A simple and general visible-light-mediated oxidation of organoboron compounds has been developed with rose bengal as the photocatalyst, substoichiometric Et3N as the electron donor, as well as air as the oxidant. This mild and metal-free protocol shows a broad substrate scope and provides a wide range of aliphatic alcohols and phenols in moderate to excellent yields. Notably, the robustness of this method is demonstrated on the stereospecific aerobic oxidation of organoboron compounds.
- Weng, Wei-Zhi,Liang, Hao,Zhang, Bo
-
supporting information
p. 4979 - 4983
(2018/08/24)
-
- Photoinduced Deaminative Borylation of Alkylamines
-
An operationally simple deaminative borylation reaction of primary alkylamines has been developed. The formation of electron-donor-acceptor complexes between N-alkylpyridinium salts and bis(catecholato)diboron enables photoinduced single-electron transfer and fragmentation to carbon-centered radicals, which are subsequently borylated. The mild conditions allow a diverse range of readily available alkylamines to be efficiently converted into synthetically valuable alkylboronic esters under catalyst-free conditions.
- Wu, Jingjing,He, Lin,Noble, Adam,Aggarwal, Varinder K.
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supporting information
p. 10700 - 10704
(2018/09/06)
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- Cobalt-Catalyzed C-H Borylation of Alkyl Arenes and Heteroarenes Including the First Selective Borylations of Secondary Benzylic C-H Bonds
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A cobalt di-tert-butoxide complex bearing N-heterocyclic carbene (NHC) ligands has been synthesized and characterized. This complex is effective at catalyzing the selective monoborylation of the benzylic position of alkyl arenes using pinacolborane (HBpin) as the boron source. This same cobalt complex enables selective monoborylation of N-methylpyrrole, N-methylpyrazole, and N-methylindole. Catalysis can be achieved with as little as 2-3 mol % of the cobalt precatalyst at 80 °C.
- Jayasundara, Chathurika R. K.,Sabasovs, Dmitrijs,Staples, Richard J.,Oppenheimer, Jossian,Smith, Milton R.,Maleczka, Robert E.
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p. 1567 - 1574
(2018/06/04)
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- METHODS FOR PREPARING A BORONIC ACID OR A BORONIC ESTER
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Methods are disclosed for converting a carboxylic acid by using a diboron reagent to convert the carboxylic acid or imide ester derivative of a carboxylic acid to a boronic ester. The method may involve providing an imide ester, such as a phthalimide ester, of a carboxylic acid, and treating the imide ester with a diboron reagent, thereby forming a boronic ester. The diboron reagent may be selected from bis(catecholato)diboron, B2(OH)4 or a mixture thereof, optionally in the presence of catechol.
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-
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- Method for synthesizing alkylborate compound
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The invention discloses a method for synthesizing an alkylborate compound, and concretely relates to a method for synthesizing the alkylborate compound through a cross-coupling reaction of chloralkaneand bis(pinacolato)diboron in the presence of metallic magnesium with Fe(acac)3 (acac = an acetylacetonate group) as a single component catalyst. The method for synthesizing the alkylborate compoundavoids the use of sensitive metal organic solvents and multi-component catalysts, realizes bilateral utilization of the bis(pinacolato)diboron, greatly reduces the use amount of the bis(pinacolato)diboron, and allows the coupling reaction of the cheap and easily-available chloralkane to be smoothly carried out under mild conditions; and compared with methods reported in literatures, the method disclosed in the invention has a better atom economy, a same or higher catalysis efficiency and a wider substrate applicability.
- -
-
Paragraph 0018
(2018/05/01)
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- Benzyltriboronates: Building Blocks for Diastereoselective Carbon-Carbon Bond Formation
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A highly diastereoselective carbon-carbon bond-forming reaction involving the tandem coupling of benzyltriboronates, enoates, and alkyl halides is described. This method was enabled by the discovery of α-diimine nickel catalysts that promote the chemosele
- Palmer, W. Neil,Zarate, Cayetana,Chirik, Paul J.
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supporting information
p. 2589 - 2592
(2017/03/01)
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- Photoinduced decarboxylative borylation of carboxylic acids
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The conversion of widely available carboxylic acids into versatile boronic esters would be highly enabling for synthesis. We found that this transformation can be effected by illuminating the N-hydroxyphthalimide ester derivative of the carboxylic acid under visible light at room temperature in the presence of the diboron reagent bis(catecholato)diboron. A simple workup allows isolation of the pinacol boronic ester. Experimental evidence suggests that boryl radical intermediates are involved in the process. The methodology is illustrated by the transformation of primary, secondary, and tertiary alkyl carboxylic acids as well as a diverse range of natural-product carboxylic acids, thereby demonstrating its broad utility and functional group tolerance.
- Fawcett, Alexander,Pradeilles, Johan,Wang, Yahui,Mutsuga, Tatsuya,Myers, Eddie L.,Aggarwal, Varinder K.
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p. 283 - 286
(2017/07/27)
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- Synthesis of Benzyl-, Allyl-, and Allenyl-boronates via Copper-Catalyzed Borylation of Alcohols
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Alcohols are among the most abundant and readily available organic feedstocks in industrial processes. The direct catalytic functionalization of sp3 C-O bonds of alcohols remains the main challenge in this field. Here, we report a copper-cataly
- Mao, Lujia,Szabó, Kálmán J.,Marder, Todd B.
-
supporting information
p. 1204 - 1207
(2017/03/14)
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- Metal-organic layers stabilize earth-abundant metal-terpyridine diradical complexes for catalytic C-H activation
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We report the synthesis of a terpyridine-based metal-organic layer (TPY-MOL) and its metalation with CoCl2 and FeBr2 to afford CoCl2·TPY-MOL and FeBr2·TPY-MOL, respectively. Upon activation with NaEt3
- Lin, Zekai,Thacker, Nathan C.,Sawano, Takahiro,Drake, Tasha,Ji, Pengfei,Lan, Guangxu,Cao, Lingyun,Liu, Shubin,Wang, Cheng,Lin, Wenbin
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p. 143 - 151
(2018/01/02)
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- Cobalt-Catalyzed Benzylic Borylation: Enabling Polyborylation and Functionalization of Remote, Unactivated C(sp3)-H Bonds
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Cobalt dialkyl and bis(carboxylate) complexes bearing α-diimine ligands have been synthesized and demonstrated as active for the C(sp3)-H borylation of a range of substituted alkyl arenes using B2Pin2 (Pin = pinacolate) as the boron source. At longer reaction times, rare examples of polyborylation were observed, and in the case of toluene, all three benzylic C-H positions were functionalized. Coupling benzylic C-H activation with alkyl isomerization enabled a base-metal-catalyzed method for the borylation of remote, unactivated C(sp3)-H bonds.
- Palmer, W. Neil,Obligacion, Jennifer V.,Pappas, Iraklis,Chirik, Paul J.
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supporting information
p. 766 - 769
(2016/02/05)
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- Visible-Light Photoredox Borylation of Aryl Halides and Subsequent Aerobic Oxidative Hydroxylation
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Efficient and practical visible-light photoredox borylation of aryl halides and subsequent aerobic oxidative hydroxylation were developed. The protocols use readily available aryl halides and bis(pinacolato)diboron as the starting materials, fac-Ir(ppy)3 as the photocatalyst, and corresponding arylboronic esters and phenols were obtained in good yields. The methods show some advantages including simple equipment, mild conditions, easy operation, and wide substrate scope. Therefore, they should provide a valuable strategy for chemical transformations.
- Jiang, Min,Yang, Haijun,Fu, Hua
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supporting information
p. 5248 - 5251
(2016/11/02)
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- Preparation method of benzyl boron ester compound
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The invention discloses a preparation method of a benzyl boron ester compound. According to the preparation method, aromatic boric acid Ar-B(OH)2, trimethyl silicon-based diazomethane, pinacol and tetrabutyl ammonium fluoride are subjected to a reaction in an organic solvent so as to obtain a benzyl pinacol boron ester compound, wherein Ar represents a non-heterocyclic aromatic group. After the method is adopted, the benzyl boron ester compound is obtained by starting from the aromatic boric acid and converting under a one-pot condition; the method is mild in reaction conditions, the reaction related to the method occurs smoothly in the air without needing strict water-free and oxygen-free conditions, and the method is convenient and simple to operate; the method has better tolerance and universality for functional groups and does not need an expensive metal catalyst and a ligand, thus being lower in reaction cost and being widely used for preparing the benzyl boron ester compound.
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Paragraph 0033; 0034; 0035; 0036; 0037; 0038; 0039-0045
(2017/06/02)
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- Pd-catalyzed cross-coupling of 1,1-diborylalkanes with aryl triflates
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The Pd-catalyzed synthesis of benzylboronic esters through coupling of aryl triflates with 1,1-diborylalkane under ambient conditions is described. Varieties of primary and secondary arylboronic esters could be successfully synthesized by this strategy. C
- Cui, Long-Can,Zhang, Zhen-Qi,Lu, Xi,Xiao, Bin,Fu, Yao
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p. 51932 - 51935
(2016/06/13)
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- Nickel-Catalyzed Borylation of Aryl- and Benzyltrimethylammonium Salts via C-N Bond Cleavage
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By developing a mild Ni-catalyzed system, a method for direct borylation of sp2 and sp3 C-N bonds has been established. The key to this hightly efficient C-N bond borylative cleavage depends on the appropriate choice of the nickel catalyst Ni(COD)2, ICy·HCl as a ligand, and the use of 2-ethoxyethanol as the cosolvent. This transformation shows good functional group compatibility and can serve as a powerful synthetic tool for gram-scale synthesis and late-stage C-N borylation of complex compounds.
- Hu, Jiefeng,Sun, Heqing,Cai, Wangshui,Pu, Xinghui,Zhang, Yemin,Shi, Zhuangzhi
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- Highly efficient synthesis of alkylboronate esters via Cu(II)-Catalyzed borylation of unactivated alkyl bromides and chlorides in air
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A copper(II)-catalyzed borylation of alkyl halides with bis(pinacolato)diboron (B2pin2) has been developed, which can be carried out in air, providing a wide range of primary, secondary, and some tertiary alkylboronates in high yields. A variety of functional groups are tolerated and the protocol is also applicable to unactivated alkyl chlorides (including 1,1- and 1,2-dichlor-ides). Preliminary mechanistic investigations show that this borylation reaction involves one-electron processes.
- Bose, Shubhankar Kumar,Brand, Simon,Omoregie, Helen Oluwatola,Haehnel, Martin,Maier, Jonathan,Bringmann, Gerhard,Marder, Todd B.
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p. 8332 - 8335
(2018/05/22)
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- Rhodium-Catalyzed ortho-Selective C-F Bond Borylation of Polyfluoroarenes with Bpin-Bpin
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An ortho-selective C-F bond borylation between N-heterocycle-substituted polyfluoroarenes and Bpin-Bpin with simple and commercially available [Rh(cod)2]BF4 as a catalyst is now reported. The reaction proceeds under mild reaction con
- Guo, Wen-Hao,Min, Qiao-Qiao,Gu, Ji-Wei,Zhang, Xingang
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supporting information
p. 9075 - 9078
(2015/08/03)
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- Iridium-Catalyzed Borylation of Primary Benzylic C-H Bonds without a Directing Group: Scope, Mechanism, and Origins of Selectivity
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Primary benzylic boronate esters are useful intermediates in organic synthesis, but these reagents cannot be prepared by hydroboration. The benzylic C-H borylation of methylarenes would be a method to form these products, but such reactions without neat methylarene or a directing group are unknown. We report an approach to divert the borylation of methylarenes from aromatic positions to benzylic positions with a silylborane as reagent and a new iridium catalyst containing an electron-deficient phenanthroline as ligand. This system forms benzylic boronate esters selectively over the corresponding aryl boronate esters. An Ir diboryl monosilyl complex ligated by the phenanthroline was isolated and determined to be the resting state of the catalyst. Mechanistic studies show that this complex is kinetically competent to be an intermediate in the catalytic process. Kinetic studies of benzylic and aryl C-H borylation catalyzed by various Ir complexes show that the rate of aryl C-H borylation decreases with decreasing electron density at the metal center of the Ir catalyst, but that the rate of benzylic C-H borylation is less sensitive to the degree of electron density at the metal center of the Ir catalyst. Kinetic and computational studies suggest that the two borylation reactions respond differently to the degree of electron density at the metal center because they occur with different turnover-limiting steps. The turnover-limiting step in the borylation of aryl C-H bonds is known to be C-H oxidative addition, but the turnover-limiting step of the borylation of benzylic C-H bonds appears to be an isomerization prior to C-B reductive elimination.
- Larsen, Matthew A.,Wilson, Conner V.,Hartwig, John F.
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supporting information
p. 8633 - 8643
(2015/07/15)
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- Borylation of primary and secondary alkyl bromides catalyzed by Cu2O nanoparticles
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A Cu2O nanoparticle catalyzed borylation of activated and unactivated alkyl bromides is developed, using bis(pinacolato)diboron as a boron source. To the best of our knowledge this is the first report of a heterogeneous Cu2O nanocata
- Zhou, Xin-Feng,Wu, Ya-Dong,Dai, Jian-Jun,Li, Yong-Jia,Huang, Yu,Xu, Hua-Jian
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p. 46672 - 46676
(2015/06/16)
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- Nickel-catalyzed borylation of arenes and indoles via C-H bond cleavage
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The first nickel-catalyzed method for the borylation of carbon-hydrogen bonds in arenes and indoles is described. The use of an N-heterocyclic carbene ligand is essential for an efficient reaction, with an N-cyclohexyl-substituted derivative being optimal. This method is readily applied to the gram scale synthesis of 2-borylindole.
- Furukawa, Takayuki,Tobisu, Mamoru,Chatani, Naoto
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supporting information
p. 6508 - 6511
(2015/04/14)
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- Making Dimethylamino a Transformable Directing Group by Nickel-Catalyzed C-N Borylation
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The dimethylamino (Me2N) group is arguably the most versatile functional group capable of highly efficient and site-selective directed aromatic functionalizations at the ortho-, meta-, and para-positions depending on reaction conditions. While the repertoire of Me2N-directed reactions is growing at a rapid pace, the lack of a general method to transform this group to other functionalities hampers its wider application in organic synthesis. Here we report nickel-catalyzed C-N borylations of aryl- and benzyl-dimethylamines that permit the conversion of a huge library of largely underutilized Me2N-containing organic molecules into various functional molecules by taking advantage of the wealth of existing C-B functionalization methods.
- Zhang, Hua,Hagihara, Shinya,Itami, Kenichiro
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p. 16796 - 16800
(2015/11/16)
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- Iron-catalyzed borylation of alkyl electrophiles
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The use of low-cost iron(III) acetoacetate (Fe(acac)3) and tetramethylethylenediamine (TMEDA) enables the direct cross-coupling of alkyl halides with bis(pinacolato)diboron. This approach allows for the borylation of activated or unactivated primary, secondary, and tertiary bromides. Moreover, even the borylation of benzylic or allylic chlorides, tosylates, and mesylates are possible. The reactions proceed under mild conditions at room temperature and show broad functional-group compatibility and "robustness" as measured by a modified Glorius robustness screen.
- Atack, Thomas C.,Lecker, Rachel M.,Cook, Silas P.
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supporting information
p. 9521 - 9523
(2014/07/22)
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