- Aromatization as an Impetus to Harness Ketones for Metallaphotoredox-Catalyzed Benzoylation/Benzylation of (Hetero)arenes
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Herein we report ketones as feedstock materials in radical cross-coupling reactions under Ni/photoredox dual catalysis. In this approach, simple condensation first converts ketones into prearomatic intermediates that then act as activated radical sources for cross-coupling with aryl halides. Our strategy enables the direct benzylation/benzoylation of (hetero)arenes under mild reaction conditions with high functional group tolerance.
- Lee, Shao-Chi,Li, Li-Yun,Tsai, Zong-Nan,Lee, Yi-Hsin,Tsao, Yong-Ting,Huang, Pin-Gong,Cheng, Cheng-Ku,Lin, Heng-Bo,Chen, Ting-Wei,Yang, Chung-Hsin,Chiu, Cheng-Chau,Liao, Hsuan-Hung
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- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
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Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
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supporting information
p. 1653 - 1665
(2021/06/17)
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- Para-selective borylation of monosubstituted benzenes using a transient mediator
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Herein, we conceptualized a transient mediator approach that has the capability of para-selective C-H functionalization of monosubstituted aromatics. This approach is enabled by in situ generation of a versatile sulfonium salt via highly electrophilic phenoxathiine or thianthrene dication intermediate which can be readily generated from its sulfoxide with trifluoromethanesulfonic anhydride. Preliminary mechanistic study implied that the remarkable para selectivity might be related to the incredible electrophilicity of thianthrene dication intermediate. The versatility of this approach was demonstrated via para-borylation of various monosubstituted simple aromatics combining the sulfonium salt formation with further photocatalyzed transformation.
- Wu, Jie,Wang, Zengwei,Chen, Xiao-Yue,Wu, Yichen,Wang, Daoming,Peng, Qian,Wang, Peng
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p. 336 - 340
(2019/12/09)
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- Pd-Catalyzed Site-Selective Borylation of Simple Arenes via Thianthrenation?
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Site-selective borylation of simple arenes was realized in one pot via an electrophilic thianthrenation/Pd-catalyzed borylation sequence. The key to achieve this operatically simple process is the use of Pd catalysis, which could tolerate the solvent and acidic conditions used in the thianthrenation step. This protocol features mild conditions, broad functional group tolerance, and simple manipulations, and is suitable for late-stage functionalization of a wide range of pharmaceuticals and complex bioactive molecules.
- Chen, Xiao-Yue,Huang, Yu-Hao,Zhou, Jian,Wang, Peng
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p. 1269 - 1272
(2020/08/13)
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- LiHMDS-Promoted Palladium or Iron-Catalyzed ipso-Defluoroborylation of Aryl Fluorides
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A novel and efficient method for the synthesis of arylboronic acid pinacol esters via a palladium- or iron-catalyzed cross-coupling reaction of aryl fluorides with bis(pinacolato)diboron (B2pin2) in the presence of LiHMDS was developed. The Pd-catalyzed defluoroborylation of fluoroarenes is compatible with a variety of functional groups such as primary and secondary amine, ketone, trifluoromethyl, alkoxy, and boryl. Remarkably, no external ligand is required for enhanced conversion efficiency.
- Zhao, Xianghu,Wu, Mingsheng,Liu, Yisen,Cao, Song
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supporting information
p. 5564 - 5568
(2018/09/12)
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- Simple and Efficient Generation of Aryl Radicals from Aryl Triflates: Synthesis of Aryl Boronates and Aryl Iodides at Room Temperature
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Despite the wide use of aryl radicals in organic synthesis, current methods to prepare them from aryl halides, carboxylic acids, boronic acids, and diazonium salts suffer from limitations. Aryl triflates, easily obtained from phenols, are promising aryl radical progenitors but remain elusive in this regard. Inspired by the single electron transfer process for aryl halides to access aryl radicals, we developed a simple and efficient protocol to convert aryl triflates to aryl radicals. Our success lies in exploiting sodium iodide as the soft electron donor assisted by light. This strategy enables the scalable synthesis of two types of important organic molecules, i.e., aryl boronates and aryl iodides, in good to high yields, with broad functional group compatibility in a transition-metal-free manner at room temperature. This protocol is anticipated to find potential applications in other aryl-radical-involved reactions by using aryl triflates as aryl radical precursors.
- Liu, Wenbo,Yang, Xiaobo,Gao, Yang,Li, Chao-Jun
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supporting information
p. 8621 - 8627
(2017/07/06)
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- Pyrazolopyrimidine derivative, preparation method, pharmaceutical composition and application
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The invention discloses a pyrazolopyrimidine derivative, a preparation method, a pharmaceutical composition and application. The invention provides the pyrazolopyrimidine derivative as shown in a formula I and stereoisomer or solvate or pharmaceutically acceptable salts or active metabolite or prodrug thereof. The pyrazolopyrimidine derivative as shown in the formula I has good inhibitory activity on Bruton's tyrosine kinase (Btk) and particularly has good in vitro and in vivo inhibitory activity on growth of tumor cells, and a good marketization prospect is achieved. Please see the formula I in the description.
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Paragraph 0325; 0326; 0327
(2017/07/19)
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- Nickel-Catalyzed Cross-Electrophile Coupling with Organic Reductants in Non-Amide Solvents
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Cross-electrophile coupling of aryl halides with alkyl halides has thus far been primarily conducted with stoichiometric metallic reductants in amide solvents. This report demonstrates that the use of tetrakis(dimethylamino)ethylene (TDAE) as an organic reductant enables the use of non-amide solvents, such as acetonitrile or propylene oxide, for the coupling of benzyl chlorides and alkyl iodides with aryl halides. Furthermore, these conditions work for several electron-poor heterocycles that are easily reduced by manganese. Finally, we demonstrate that TDAE addition can be used as a control element to ‘hold’ a reaction without diminishing yield or catalyst activity.
- Anka-Lufford, Lukiana L.,Huihui, Kierra M. M.,Gower, Nicholas J.,Ackerman, Laura K. G.,Weix, Daniel J.
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supporting information
p. 11564 - 11567
(2016/08/05)
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- Cobalt co-catalysis for cross-electrophile coupling: Diarylmethanes from benzyl mesylates and aryl halides
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The nickel-catalyzed cross-coupling of aryl halides with alkyl radicals derived from alkyl halides has recently been extended to couplings with carbon radicals generated by a co-catalyst. In this study, a new co-catalyst, cobalt phthalocyanine (Co(Pc)), is introduced and demonstrated to be effective for coupling substrates not prone to homolysis. This is because Co(Pc) reacts with electrophiles by an SN2 mechanism instead of by the electron-transfer or halogen abstraction mechanisms previously explored. Studies demonstrating the orthogonal reactivity of (bpy)Ni and Co(Pc), applying this selectivity to the coupling of benzyl mesylates with aryl halides, and the adaptation of these conditions to the less reactive benzyl phosphate ester and an enantioconvergent reaction are presented.
- Ackerman, Laura K. G.,Anka-Lufford, Lukiana L.,Naodovic, Marina,Weix, Daniel J.
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p. 1115 - 1119
(2015/02/05)
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- Isocytosine-based inhibitors of xanthine oxidase: Design, synthesis, SAR, PK and in vivo efficacy in rat model of hyperuricemia
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Structure-activity relationship studies were carried out for lead generation following structure-guided design approach from an isocytosine scaffold identified earlier for xanthine oxidase inhibition. A 470-fold improvement in in vitro IC50 was obtained in the process. Five most potent compounds with nanomolar IC50 values were selected for pharmacokinetics and in vivo experiments. The best compound showed good in vivo activity when administered intraperitoneally but was not active by oral route. The results suggest that improvement in oral exposure could improve the in vivo efficacy of this series.
- Khanna, Smriti,Burudkar, Sandeep,Bajaj, Komal,Shah, Pranay,Keche, Ashish,Ghosh, Usha,Desai, Avani,Srivastava, Ankita,Kulkarni-Almeida, Asha,Deshmukh, Nitin J.,Dixit, Amol,Brahma, Manoja K.,Bahirat, Umakant,Doshi, Lalit,Nemmani, Kumar V.S.,Tannu, Prashant,Damre, Anagha,B-Rao, Chandrika,Sharma, Rajiv,Sivaramakrishnan
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p. 7543 - 7546
(2013/02/22)
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- O-benzyl trichloroacetimidates having electron-withdrawing substituents in acid-catalyzed diarylmethane synthesis
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Reaction of O-benzyl trichloroacetimidates having electron-withdrawing substituents with arenes in the presence of catalytic amounts of TMSOTf gave the corresponding diarylmethanes in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Zhang, Jianjun,Schmidt, Richard R.
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p. 1729 - 1733
(2008/02/04)
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