- Electrochemical Fluorination of Vinyl Boronates through Donor-Stabilized Vinyl Carbocation Intermediates**
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The electrochemical generation of vinyl carbocations from alkenyl boronic esters and boronates is reported. Using easy-to-handle nucleophilic fluoride reagents, these intermediates are trapped to form fully substituted vinyl fluorides. Mechanistic studies support the formation of dicoordinated carbocations through sequential single-electron oxidation events. Notably, this electrochemical fluorination features fast reaction times and Lewis acid-free conditions. This transformation provides a complementary method to access vinyl fluorides with simple fluoride salts such as TBAF.
- Wigman, Benjamin,Lee, Woojin,Wei, Wenjing,Houk, Kendall N.,Nelson, Hosea M.
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- Stereospecific Iron-Catalyzed Carbon (sp2)-Carbon (sp2) Cross-Coupling of Aryllithium with Vinyl Halides
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We present herein an efficient synthetic protocol involving iron-catalyzed cross-coupling of organolithium compounds with vinyl halides as key coupling partners. More than 30 examples were obtained with moderate to good yields and high stereoselectivities. The practicality of this method is evidenced by a gram-scale synthesis. In addition, a preliminary mechanistic investigation was also performed.
- Chen, Peng,Peng, Xiao-Shui,Wang, Zhi-Yong,Wong, Henry N. C.
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supporting information
p. 4385 - 4390
(2021/06/27)
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- Silver-Catalysed Hydroarylation of Highly Substituted Styrenes
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Hydroarylation is an effective strategy to rapidly increase the complexity of organic structures by transforming flat alkene moieties into three-dimensional frameworks. Many strategies have already been developed to achieve the hydroarylation of styrenes,
- Dalton, Toryn,Gre?ies, Steffen,Das, Mowpriya,Niehues, Maximilian,Schrader, Malte L.,Gutheil, Christian,Ravoo, Bart Jan,Glorius, Frank
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p. 8537 - 8541
(2021/03/16)
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- Enantioselective Oxy-Heck–Matsuda Arylations: Expeditious Synthesis of Dihydrobenzofuran Systems and Total Synthesis of the Neolignan (?)-Conocarpan
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This work discloses the first examples of an effective enantioselective oxy-Heck–Matsuda reaction using a variety of styrenic olefins to generate chiral dihydrobenzofurans. The reaction proceeds in moderate to good yields, with high trans diastereoselectivity (up to 20:1) in enantioselectivities up to 90:10 using the N,N-ligand pyrimidine-bisoxazoline (PyriBox). The oxy-Heck–Matsuda reactions were carried out under mild conditions and rather low catalyst loadings. The feasibility and practicality of the process is demonstrated by a concise total synthesis of the neolignan (?)-conocarpan. X-ray diffraction of an advanced brominated intermediate in the route to (?)-conocarpan has allowed the unequivocal assignment of the absolute stereochemistry of the oxy-Heck–Matsuda aryldihydrobenzofuran products. A rationale for the mechanism operating in these enantioselective oxy-Heck–Matsuda reactions is also presented. (Figure presented.).
- Silva, Allan R.,Polo, Ellen C.,Martins, Nelson C.,Correia, Carlos Roque D.
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p. 346 - 365
(2018/01/26)
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- Switchable Synthetic Strategy toward Trisubstituted and Tetrasubstituted Exocyclic Alkenes
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An efficient and facile method for the construction of tri- or tetrasubstituted exocyclic alkenes is achieved via a Cu(I)-catalytic system. This protocol exhibits mild conditions, low-cost catalyst, good functional group tolerance, and good yields. The selectivity toward tri- or tetrasubstituted alkenes can be delicately controlled by adjustment of base and solvent. A preliminary mechanism study manifested that the reaction undergoes a radical process, where B2pin2 plays an indispensable role.
- Zhou, Sen,Yuan, Fangyuan,Guo, Minjie,Wang, Guangwei,Tang, Xiangyang,Zhao, Wentao
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p. 6710 - 6714
(2018/11/21)
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- Synthesis of α-Arylated Cycloalkanones from Congested Trisubstituted Spiro-epoxides: Application of the House-Meinwald Rearrangement for Ring Expansion
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A three-step sequence for the synthesis of α-arylated cyclohexanones and the most challenging cycloheptanones is reported. First, an efficient one-pot synthesis of β,β'-disubstituted benzylidene cycloalkanes (styrenes) using the palladium-catalyzed Barluenga reaction from readily available feedstock chemicals is described. Furthermore, an epoxidation followed by the House-Meinwald rearrangement (HMR) of spiro-epoxides is reported to produce a number of α-arylated cycloalkanones upon ring expansion. Reactions catalyzed by bismuth triflate underwent quasi-exclusively ring expansion for all substrates (electronically poor and rich), with yields ranging from 15% to 95%, thus demonstrating the difficulty of achieving ring enlargement for electron-deficient spiro-epoxides. On the other hand, by means of catalysis with aluminum trichloride, the rearrangement of spiro-epoxides proceeded typically in high yields and with remarkable regioselectivity on a broader substrate scope. In this case, a switch of regioselectivity was achieved for spiro-epoxides with electron-withdrawing substituents which enable the method to be successfully extended to some chemospecific arene shifts and the synthesis of aldehydes bearing a α-quaternary carbon. While the HMR has been extensively studied for smaller ring enlargement, we are pleased to report herein that larger cyclohexanones and cycloheptanones can be obtained efficiently from more sterically demanding trisubstituted spiro-epoxides bearing electron-releasing and electron-neutral arene substituents.
- Jeedimalla, Nagalakshmi,Jacquet, Camille,Bahneva, Diana,Youte Tendoung, Jean-Jacques,Roche, Stéphane P.
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p. 12357 - 12373
(2018/09/06)
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- SILICON-BASED CROSS COUPLING AGENTS AND METHODS OF THEIR USE
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Compositions and methods using silicon-based cross-coupling agents in the formation of carbon-carbon and carbon-nitrogen bonds are described.
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Paragraph 0056
(2016/02/10)
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- Synthesis of Exocyclic Trisubstituted Alkenes via Nickel- Catalyzed Kumada-Type Cross-Coupling Reaction of gem- Difluoroalkenes with Di-Grignard Reagents
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A practical, nickel-catalyzed Kumada-type double cross-coupling reaction of gem-difluoroalkenes with 1,4- or 1,5-di-Grignard reagents was developed. The reaction proceeded efficiently at room temperature and a variety of cyclization products, arylmethylenecyclopentanes and arylmethylenecyclohexanes, were obtained in high to excellent yields, respectively.
- Dai, Wenpeng,Zhang, Xuxue,Zhang, Juan,Lin, Yingyin,Cao, Song
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supporting information
p. 183 - 187
(2016/02/16)
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- SILICON-BASED CROSS COUPLING AGENTS AND METHODS OF THEIR USE
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Compositions and methods using silicon-based cross-coupling agents in the formation of carbon-carbon and carbon-nitrogen bonds are described.
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Paragraph 0050
(2014/01/08)
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- Palladium-catalyzed alkyne insertion/reduction route to trisubstituted olefins
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A new route to trisubstituted olefins through a palladium-catalyzed alkyne insertion/reduction reaction with unactivated alkyl iodides is reported. The reaction proceeds under mild conditions and tolerates a range of functional groups and substitution patterns. Preliminary mechanistic inquiry suggests that the transformation may proceed through a hybrid radical/organometallic pathway.
- Fruchey, Erin R.,Monks, Brendan M.,Patterson, Andrea M.,Cook, Silas P.
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supporting information
p. 4362 - 4365
(2013/09/24)
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- Unification of anion relay chemistry with the Takeda and Hiyama cross-coupling reactions: Identification of an effective silicon-based transfer agent
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The unification of Anion Relay Chemistry (ARC) with the Takeda and Hiyama palladium-mediated cross-coupling processes to provide aryl-aryl, alkenyl-aryl, and alkenyl-alkenyl coupled products by exploiting a common silicon-based transfer agent has been achieved. These results provide a practical solution for intermolecular cross-coupling of organolithium reagents without the problematic lithium-halogen exchange and/or undesired homocoupling that has kept organolithium cross-couplings from achieving the same level of utility asother palladium-mediated methods (e.g., Suzuki organoboron, Negishi organozinc, Stille organotin, Kumada organomagnesium, etc.).
- Smith III, Amos B.,Hoye, Adam T.,Martinez-Solorio, Dionicio,Kim, Won-Suk,Tong, Rongbiao
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supporting information; experimental part
p. 4533 - 4536
(2012/04/23)
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- Magnesiation of electron-rich aryl bromides and their use in nickel-catalyzed cross-coupling reactions
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Electron-rich aryl bromides are rapidly converted to the corresponding lithium triarylmagnesiates with (n-Bu)3MgLi, which undergo efficient nickel-catalyzed Kumada-Corriu cross-coupling reactions with a variety of aryl and alkenyl bromides, chlorides, tosylates, and triflates.
- Lau, Stephen Y. W.,Hughes, Greg,O'Shea, Paul D.,Davies, Ian W.
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p. 2239 - 2242
(2008/02/03)
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- A sulfoxide version of the Julia-Lythgoe olefination: A new method for the synthesis of olefins from carbonyl compounds and sulfoxides with carbon-carbon coupling
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Reaction of β-mesyloxy (or acetoxy) sulfoxides, derived from alkyl (or arylmethyl) phenyl sulfoxides and carbonyl compounds in two steps, with alkylmetals (n-BuLi, t-BuLi, or EtMgBr) at low temperature gave olefins in good to excellent yields. When the β-hydroxy sulfoxides derived from arylaldehydes were treated with mesyl chloride in the presence of triethylamine, the sulfoxides directly gave E-olefins in good yields. These reactions offer a sulfoxide version of the Julia-Lythgoe olefination. The reductive vicinal elimination was found to take place through the direct sulfoxide-metal exchange. The stereochemistry of the elimination was investigated and found to be stereospecific; however, the stereospecificity was found to be dependent on the substrates. (C) 2000 Elsevier Science Ltd.
- Satoh, Tsuyoshi,Hanaki, Noriko,Yamada, Noriko,Asano, Tohru
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p. 6223 - 6234
(2007/10/03)
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- Cyclization of α,ω-diborylalkanes via double Suzuki-Miyaura coupling
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Both carbo- and heterocyclic six-membered ring systems (3) containing an exocyclic carbon-carbon double bond have been prepared (25-76%) from α,ω-dienes (1) through the cross coupling of their dihydroboration products (2) with either aromatic or aliphatic vinylidene dibromides (4) in a one-pot Pd-catalyzed sequence.
- Soderquist, John A.,Leon, Gisela,Colberg, Juan C.,Martinez, Isamir
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p. 3119 - 3122
(2007/10/02)
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- Photolysis of 1,1,1-Triarylalkane. A New Photochemical Carbene Generation Process
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Upon UV irradiation in methanol some 1,1,1-triarylalkanes underwent an α,α-elimination of two aryl groups to give biaryls and the corresponding carbene intermediates, which inserted into the OH bond of the methanol to afford methyl ethers and/or underwent a 1,2-H shift to afford olefins.Furthermore, the efficieny of this elimination was highly dependent upon the bulkiness of the alkyl groups.
- Shi, Min,Okamoto, Yoshiki,Takamuku, Setsuo
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p. 3821 - 3824
(2007/10/02)
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