- 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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- 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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- Decarboxylative Borylation of Stabilized and Activated Carbon Radicals
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Redox-active esters (RAEs) as active radical precursors have been extensively studied for C?B bond formations. However, the analogous transformations of stabilized radicals from the corresponding acid precursors remain challenging owing to the strong preference towards single-electron oxidation to the stable carbocations. This work describes a general strategy for rapid access to various aliphatic and aromatic boronic esters by mild photoinduced decarboxylative borylation. Both aryl and alkyl radicals could be generated from the leaving group-assisted N-hydroxybenzimidoyl chloride esters, even α-CF3 substituted substrates could be activated for further elaboration.
- Li, Xiaojuan,Ni, Shengyang,Pan, Yi,Wang, Yi,Zhang, Qiang,Zhang, Weigang
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supporting information
p. 21875 - 21879
(2020/10/02)
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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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- IMIDAZOPYRAZINONES, PYRAZOLOPYRIMIDINONES AND PYRAZOLOPYRIDINONES AS PDE1 INHIBITORS
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The present invention provides compounds according to formula (I) below that are PDE1 enzyme inhibitors and their use as medicaments, in particular for the treatment of neurodegenerative disorders and psychiatric disorders. The present invention also provides pharmaceutical compositions comprising compounds of the invention and methods of treating disorders using the compounds of the invention.
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Page/Page column 51
(2018/05/16)
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- 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
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supporting information
p. 4979 - 4983
(2018/08/24)
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- Copper(II)-Catalyzed Asymmetric Photoredox Reactions: Enantioselective Alkylation of Imines Driven by Visible Light
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Asymmetric photoredox catalysis offers exciting opportunities to develop new synthetic approaches to chiral molecules through novel reaction pathways. Employing the first-row transition metal complexes as the chiral photoredox catalysts remains, however, a formidable challenge, although these complexes are economic, environmentally friendly, and often exhibit special reactivities. We report in this Article the development of one class of highly efficient asymmetric/photoredox bifunctional catalysts based on the copper(II) bisoxazoline complexes (CuII-BOX) for the light-induced enantioselective alkylation of imines. The reactions proceed under very mild conditions and without a need for any other photosensitizer. The simple catalytic system and readily tunable chiral ligands enable a significantly high level of enantioselectivity for the formation of chiral amine products bearing a tetrasubstituted carbon stereocenter (36 examples, up to 98% ee). Overall, the CuII-BOX catalysts initiate the radical generation, and also govern the subsequent stereoselective transformations. This strategy utilizing chiral complexes comprised of a first-row transition metal and a flexible chiral ligand as the asymmetric photoredox catalysts provides an effective platform for the development of green asymmetric synthetic methods.
- Li, Yanjun,Zhou, Kexu,Wen, Zhaorui,Cao, Shi,Shen, Xiang,Lei, Meng,Gong, Lei
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supporting information
p. 15850 - 15858
(2018/11/23)
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- CU-AND NI-CATALYZED DECARBOXYLATIVE BORYLATION REACTIONS
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The invention is directed to methods of converting a carboxylic acid group in a compound, via a redox active ester, to a corresponding boronic ester by treatment with bis(pinacolato)diboron-alkyllithium complex in the presence of a ligand, a Ni(ll) salt or a copper salt, and an Mg(ll) salt, in the presence of an alkyllithium or a lithium hydroxide or alkoxide salt. The product pinacolato boronate ester can be cleaved to provide a boronic acid. The invention is also directed to methods of preparing various compounds of medical value comprising boronic acid groups, and to novel boronic-acid containing compounds of medicinal value, including an atorvastatin boronic acid analog, a vancomycin aglycone boronic acid analog, and boronic acid containing elastase inhibitors mCBK319, mCBK320, mCBK323, and RPX-7009.
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Page/Page column 27; 33; 35; 36-37; 73
(2018/10/19)
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- Decarboxylative borylation
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The widespread use of alkyl boronic acids and esters is frequently hampered by the challenges associated with their preparation.We describe a simple and practical method to rapidly access densely functionalized alkyl boronate esters from abundant carboxylic substituents. This broad-scope nickel-catalyzed reaction uses the same activating principle as amide bond formation to replace a carboxylic acid moiety with a boronate ester. Application to peptides allowed expedient preparations of a-amino boronic acids, often with high stereoselectivity, thereby facilitating synthesis of the alkyl boronic acid drugs Velcade and Ninlaro as well as a boronic acid version of the iconic antibiotic vancomycin. The reaction also enabled the discovery and extensive biological characterization of potent human neutrophil elastase inhibitors, which offer reversible covalent binding properties.
- Li, Chao,Wang, Jie,Barton, Lisa M.,Yu, Shan,Tian, Maoqun,Peters, David S.,Kumar, Manoj,Yu, Antony W.,Johnson, Kristen A.,Chatterjee, Arnab K.,Yan, Ming,Baran, Phil S.
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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 0082; 0083; 0084; 0085; 0086; 0087
(2017/06/02)
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- Transition-metal-free synthesis of pinacol alkylboronates from tosylhydrazones
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Highly efficient: Pinacol alkylboronates were synthesized by the reaction of tosylhydrazones with bis(pinacolato)diboron or pinacolborane under transition-metal-free conditions. This reaction represents an expeditious conversion of carbonyl functionality into a boronate group. Copyright
- Li, Huan,Wang, Long,Zhang, Yan,Wang, Jianbo
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p. 2943 - 2946
(2012/04/18)
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- Alkylboronic esters from copper-catalyzed borylation of primary and secondary alkyl halides and pseudohalides
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Easy access: An unprecedented copper-catalyzed cross-coupling reaction of the title compounds with diboron reagents is described (see scheme; Ts=4-toluenesulfonyl). This reaction can be used to prepare both primary and secondary alkylboronic esters having diverse structures and functional groups. The resulting products would be difficult to access by other means. Copyright
- Yang, Chu-Ting,Zhang, Zhen-Qi,Tajuddin, Hazmi,Wu, Chen-Cheng,Liang, Jun,Liu, Jing-Hui,Fu, Yao,Czyzewska, Maria,Steel, Patrick G.,Marder, Todd B.,Liu, Lei
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supporting information; experimental part
p. 528 - 532
(2012/02/04)
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- PROCESS FOR PREPARING BORONIC ACIDS AND ESTERS IN THE PRESENCE OF MAGNESIUM METAL
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The present invention relates to the process for preparing a boronic acid or ester chemically, in which an aromatic compound is reacted with a boronating agent, in the presence of magnesium metal (Mg0). The invention also relates to the boronic acids or esters that can be obtained by means of this process and to the use thereof for example as a synthesis intermediate, in the Suzuki reaction, in the pharmaceutical or alternatively electronics field.
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Page/Page column 7-8
(2011/11/30)
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- An opportunity for Mg-catalyzed grignard-type reactions: Direct coupling of benzylic halides with pinacolborane with 10 mol % of magnesium
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Mg in catalytic amounts as the only metal permits the reductive coupling between benzyl halides and pinacolborane. HBpin acts both as an electrophile and as a reducing agent to regenerate an organomagnesium species in situ. An hydride oxidation mechanism is proposed on the basis of DFT calculations.
- Pintaric, Christine,Olivero, Sandra,Gimbert, Yves,Chavant, Pierre Y.,Dunach, Elisabet
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supporting information; experimental part
p. 11825 - 11827
(2010/11/02)
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- Synthesis of benzylboronates via palladium-catalyzed borylation of benzyl halides with pinacolborane
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Various benzyl halides were borylated with pinacolborane in the presence of iPr2NEt and a catalytic amount of PdCl2(PPh3)2 to afford the corresponding benzylboronates in good yields.
- Murata, Miki,Oyama, Takashi,Watanabe, Shinji,Masuda, Yuzuru
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p. 2513 - 2517
(2007/10/03)
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