- Microwave-assisted transition-metal-catalyzed synthesis of N-shifted and ring-expanded buflavine analogues
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Two novel and efficient strategies for the synthesis of hitherto unknown N-shifted and ring-expanded buflavine analogues are presented. Construction of the medium-sized ring system of the title molecules, a difficult task due to the high activation energy needed for the ring-closure with the additional rigidity imposed by the biaryl skeleton, was achieved by using Suzuki-Miyaura biaryl coupling and a ring-closing metathesis reaction as the key steps. The combination of a second-generation Grubbs catalyst and microwave irradiation proved to be highly useful in generating the otherwise difficult to obtain medium-sized ring system of the buflavine analogues.
- Appukkuttan, Prasad,Dehaen, Wim,Van Der Eycken, Erik
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- Alkylative Dearomatization by Using an Unactivated Aryl Nitro Group as a Leaving Group: Access to Diversified Alkylated Spiro[5.5]trienones
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The cleavage of an unactivated aryl nitro group triggered by alkyl radicals enables a dearomative cyclization, affording diversified alkylated spiro[5.5]trienones in good yields. Using readily available compounds (toluene and analogues, alkanes, ethers, ketones, etc.) as alkylating reagents, various alkyls have been implanted into the spirocycles via C(sp3)-H and Ar-NO2 bond activation with high functional group tolerance. This protocol provides a distinct method for the activation of the aryl nitro group.
- Xia, Dong,Duan, Xin-Fang
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supporting information
p. 2548 - 2552
(2021/05/05)
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- Synthesis, structure, and synthetic potential of arenediazonium trifluoromethanesulfonates as stable and safe diazonium salts
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Aromatic diazonium salts are valuable building blocks for organic synthesis; however, in most cases, they are unstable, unsafe, poorly soluble, and/or expensive. In this paper, we have shown that a variety of stable and safe arenediazonium triflates ArN2+ TfO– can be obtained easily and in high yields by diazotization of anilines with tert-butyl nitrite in the presence of trifluoromethanesulfonic acid. Arenediazonium triflates are relatively shelf-stable in the dry state. They dissolve well in water, as well as polar and even nonpolar organic solvents. Less than 800 J/g of energy is released during the thermal decomposition of these salts, which indicates their explosion safety. Arenediazonium triflates have a high reactivity in the known reactions of diazonium chemistry, and undergo an unusual metal-free chlorodediazonization reaction with chloroform and CCl4.
- Filimonov, Victor D.,Krasnokutskaya, Elena A.,Kassanova, Assia Zh.,Fedorova, Valentina A.,Stankevich, Ksenia S.,Naumov, Nikolay G.,Bondarev, Alexander A.,Kataeva, Veronika A.
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supporting information
p. 665 - 674
(2018/09/14)
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- Magnesium promoted autocatalytic dehydrogenation of amine borane complexes: A reliable, non-cryogenic, scalable access to boronic acids
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Owing to the unusual reactivity of dialkylamine-borane complexes, a methodology was developed to simply access boronic acids. The intrinsic instability of magnesium aminoborohydride was tweaked into a tandem dehydrogenation borylation sequence. Proceeding via an autocatalytic cycle, amineborane dehydrogenation was induced by a variety of Grignard reagents. Overall, addition of the organomagnesium species onto specially designed dialkylamine-borane complexes led to a variety of boronic acids in high yields. In addition, the reaction can be performed under Barbier conditions, on a large scale.
- Marciasini, Ludovic D.,Richard, Jimmy,Cacciuttolo, Bastien,Sartori, Guillaume,Birepinte, Melodie,Chabaud, Laurent,Pinet, Sandra,Pucheault, Mathieu
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p. 164 - 171
(2018/12/05)
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- Development of a Concise Multikilogram Synthesis of LPA-1 Antagonist BMS-986020 via a Tandem Borylation-Suzuki Procedure
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The process development for the synthesis of BMS-986020 (1) via a palladium catalyzed tandem borylation/Suzuki reaction is described. Evaluation of conditions culminated in an efficient borylation procedure using tetrahydroxydiboron followed by a tandem Suzuki reaction employing the same commercially available palladium catalyst for both steps. This methodology addressed shortcomings of early synthetic routes and was ultimately used for the multikilogram scale synthesis of the active pharmaceutical ingredient 1. Further evaluation of the borylation reaction showed useful reactivity with a range of substituted aryl bromides and iodides as coupling partners. These findings represent a practical, efficient, mild, and scalable method for borylation.
- Smith, Michael J.,Lawler, Michael J.,Kopp, Nathaniel,McLeod, Douglas D.,Davulcu, Akin H.,Lin, Dong,Katipally, Kishta,Sfouggatakis, Chris
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p. 1859 - 1863
(2017/11/24)
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- Borinic Acids via Direct Arylation of Amine-Borane Complexes: An Air- and Water-Stable Boron Source
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A synthesis of borinic acids and borinates was optimized using amine-borane complexes as a water and air insensitive borylating agent. The reaction operates under convenient conditions using a non-cryogenic temperature and with no flash chromatography, and it gives no boron impurities. The reaction proceeds through a tandem dehydrogenation-double addition mechanism.
- Richard, Jimmy,Birepinte, Mélodie,Charbonnier, Jean Baptiste,Liautard, Virginie,Pinet, Sandra,Pucheault, Mathieu
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p. 736 - 744
(2017/02/15)
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- Methanol-promoted borylation of arylamines: A simple and green synthetic method to arylboronic acids and arylboronates
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A Sandmeyer borylation of arylamines via a SN2Ar pathway promoted by methanol with sodium nitrite and hydrochloric acid as diazotization agent has been developed, which provide a simple and green synthetic method to arylboronic acids and arylboronates. Georg Thieme Verlag Stuttgart New York.
- Zhao, Cong-Jun,Xue, Dong,Jia, Zhi-Hui,Wang, Chao,Xiao, Jianliang
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p. 1577 - 1584
(2014/07/08)
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- An easy route to (hetero)arylboronic acids
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An unprecedented spontaneous reactivity between diazonium salts and diboronic acid has been unveiled, leading to a versatile arylboronic acid synthesis directly from (hetero)arylamines. This fast reaction (35 min overall) tolerates a wide range of functional groups and is carried out under very mild conditions. The radical nature of the reaction mechanism has been investigated.
- Erb, William,Hellal, Akila,Albini, Mathieu,Rouden, Jacques,Blanchet, Jerome
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p. 6608 - 6612
(2014/06/09)
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- Sequential one-pot access to molecular diversity through aniline aqueous borylation
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On the basis of our recently reported aniline aqueous borylation, molecular diversity was achieved in a one-pot process by combining other reactions such as esterification, Suzuki-Miyaura coupling, hydrogenolysis, or Petasis borono-Mannich.
- Erb, William,Albini, Mathieu,Rouden, Jacques,Blanchet, Jrme
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p. 10568 - 10580
(2015/01/08)
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- Scope of the palladium-catalyzed aryl borylation utilizing bis-boronic acid
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The Suzuki-Miyaura reaction has become one of the more useful tools for synthetic organic chemists. Until recently, there did not exist a direct way to make the most important component in the coupling reaction, namely the boronic acid. Current methods to make boronic acids often employ harsh or wasteful reagents to prepare boronic acid derivatives and require additional steps to afford the desired boronic acid. The scope of the previously reported palladium-catalyzed, direct boronic acid synthesis is unveiled, which includes a wide array of synthetically useful aryl electrophiles. It makes use of the newly available second generation Buchwald XPhos preformed palladium catalyst and bis-boronic acid. For ease of isolation and to preserve the often sensitive C-B bond, all boronic acids were readily converted to their more stable trifluoroborate counterparts.
- Molander, Gary A.,Trice, Sarah L. J.,Kennedy, Steven M.,Dreher, Spencer D.,Tudge, Matthew T.
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supporting information; experimental part
p. 11667 - 11673
(2012/09/05)
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- Palladium-catalyzed borylation of aryl and heteroaryl halides utilizing tetrakis(dimethylamino)diboron: One step greener
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The palladium-catalyzed borylation of aryl and heteroaryl halides with a novel borylating agent, tetrakis(dimethylamino)diboron [(Me2N) 2B-B(NMe2)2], is reported. The method is complementary to the previously reported method utilizing bis-boronic acid (BBA) in that certain substrates perform better under one set of optimized reaction conditions than the other. Because tetrakis(dimethylamino)diboron is the synthetic precursor to both BBA and bis(pinacolato)diboron (B 2Pin2), the new method represents a more atom-economical and efficient approach to current borylation methods.
- Molander, Gary A.,Trice, Sarah L. J.,Kennedy, Steven M.
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supporting information
p. 4814 - 4817,4
(2012/12/12)
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- Combining metallasupramolecular chemistry with dynamic covalent chemistry: Synthesis of large molecular cages
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(Figure Presented) Ru-built cube: By combining metallasupramolecular chemistry with dynamic covalent chemistry, complex nanostructures can be formed. Large cages are synthesized by reaction of trinuclear metallamacrocycles containing pendant aldehyde groups (see picture; Ru blue, aldehyde linkers green) with triamines (red).
- Granzhan, Anton,Riis-Johannessen, Thomas,Scopelliti, Rosario,Severin, Kay
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supporting information; experimental part
p. 5515 - 5518
(2010/09/16)
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- Substituent effects on aryltrifluoroborate solvolysis in water: Implications for Suzuki-Miyaura coupling and the design of stable 18F-labeled aryltrifluoroborates for use in PET imaging
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(Chemical Equation Presented) Whereas electron withdrawing substituents retard the rate of aryltrifluoroborate solvolysis, electron-donating groups enhance it. Herein is presented a Hammett analysis of the solvolytic lability of aryltrifluoroborates where log(Ksolv) values correlate to a values with a ρ value of approximately -1. This work provides a predictable rubric for tuning the reactivity of boron for several uses including 18F-labeled PET reagents and has mechanistic implications for ArBF3-enhanced ligandless metal-mediated cross coupling reactions with aryltrifluoroborates.
- Ting, Richard,Harwig, Curtis W.,Lo, Justin,Li, Ying,Adam, Michael J.,Ruth, Thomas J.,Petrin, David M.
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p. 4662 - 4670
(2008/09/20)
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- Microwave-enhanced cadogan cyclization: An easy access to the 2-substituted carbazoles and other fused heterocyclic systems
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A microwave-enhanced Suzuki-Miyaura cross-coupling reaction in combination with a microwave-assisted Cadogan reductive cyclization is presented as an easy access to a variety of 2-substituted carbazoles and other fused heterocyclic systems. Microwave irradiation was found very useful in minimizing the proto-deboronation issues in the cross-coupling reaction, and enhances the rate of reductive cyclization in a dramatic manner.
- Appukkuttan, Prasad,Van Der Eycken, Erik,Dehaen, Wim
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p. 127 - 133
(2007/10/03)
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- Cedranediolborane as a borylating agent for the preparation of boronic acids: Synthesis of a boronated nucleoside analogue
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Cedranediolborane can be cross-coupled with aryl iodides under Pd(0) catalysis to yield aryl boronates which can easily be deprotected to form the corresponding free boronic acids. The application of this methodology has led to the preparation of a boronated nucleoside indole analogue.
- Song,Morin
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p. 266 - 268
(2007/10/03)
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