- Cobalt-catalyzed coupling reaction of alkyl halides with allylic grignard reagents
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Facile construction of quaternary carbon centers: The cobalt-catalyzed coupling reaction of not only primary and secondary but also tertiary alkyl halides with allylic Grignard reagents proceeds smoothly (see scheme; dppp = 1,3-bis(diphenylphosphanyl)prop
- Tsuji, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
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- Iron nanoparticles in the coupling of alkyl halides with aryl Grignard reagents
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Iron nanoparticles, either formed in situ stabilized by 1,6-bis(diphenylphosphino)hexane or polyethylene glycol (PEG), or preformed stabilized by PEG, are excellent catalysts for the cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens and they also prove effective in a tandem cyclization/cross- coupling reaction. The Royal Society of Chemistry 2006.
- Bedford, Robin B.,Betham, Michael,Bruce, Duncan W.,Davis, Sean A.,Frost, Robert M.,Hird, Michael
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- Synthesis of alkyl sulfones from alkenes and tosylmethylphosphonium iodide through photo-promoted cc bond formation
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A new synthetic method for alkyl sulfones through CC bond formation between alkenes and tosylmethylphosphonium iodide is reported. A tosylmethyl radical is generated from the phosphonium iodide under irradiation of visible light with the aid of fac-Ir(ppy)3. It undergoes regioselective 1,2-addition across the carboncarbon double bond to afford an elongated alkyl radical, which abstracts a hydrogen atom from C6F5SH, producing an alkyl sulfone with one-carbon extension.
- Miura, Tomoya,Miyakawa, Sho,Moriyama, Daisuke,Murakami, Masahiro
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- Synergistic Hydrocobaltation and Borylcobaltation Enable Regioselective Migratory Triborylation of Unactivated Alkenes
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The structural diversity of sp3-triorganometallic reagents enhances their potentiality in the modular construction of molecular complexity in chemical synthesis. Despite significant achievements on the preparation of sp3 1,1,1- and 1,1,2-triorganometallic B,B,B-reagents, catalytic approaches that enable the installation of multiple boryl groups at skipped carbons of unactivated alkenes still remain elusive. Herein, we report a cobalt-catalyzed selective triborylation reaction of unactivated alkenes to access synthetically versatile 1,1,3-triborylalkanes. This triborylation protocol provides a general platform for regioselective trifunctionalization of unactivated alkenes, and its utility is highlighted by the synthesis of various value-added chemicals from readily accessible unactivated alkenes. Mechanistic studies, including deuterium-labelling experiments and evaluation of potential reactive intermediates, provide insight into the experimentally observed chemo- and regioselectivity.
- Ge, Shaozhong,Zhao, Yinsong
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supporting information
(2022/02/19)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- Palladium and Nickel Catalyzed Suzuki Cross-Coupling with Alkyl Fluorides
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Suzuki cross-coupling of benzylic and unactivated aliphatic fluorides with aryl- and alkenylboronic acids has been achieved via mechanistically distinct Pd and Ni catalyzed pathways that outperform competing protodeboronation, β-hydride elimination, and h
- Balaraman, Kaluvu,Wolf, Christian
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supporting information
p. 8994 - 8999
(2021/11/20)
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- Transition Metal-Free sp3?sp3 Carbon-Carbon Coupling between Benzylboronic Esters and Alkyl Bromides
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A transition metal-free coupling reaction of benzylboronic esters and alkyl halides has been developed. Both alkyl bromides and alkyl iodides were found to be competent substrates with the nucleophilic boronate intermediate generated from the combination of benzylboronic ester and an alkyllithium. Good chemoselectivity was observed for the reaction with the alkyl bromide in substrates with a second electrophile present. Both secondary and tertiary benzylboronic esters were effective nucleophiles in the reaction with primary alkyl halides. Mechanistic observations are consistent with a radical mechanism.
- Barker, Timothy J.,Russell, Richard W.
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supporting information
p. 2782 - 2784
(2021/06/25)
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- Access to Trisubstituted Fluoroalkenes by Ruthenium-Catalyzed Cross-Metathesis
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Although the olefin metathesis reaction is a well-known and powerful strategy to get alkenes, this reaction remained highly challenging with fluororalkenes, especially the Cross-Metathesis (CM) process. Our thought was to find an easy accessible, convenient, reactive and post-functionalizable source of fluoroalkene, that we found as the methyl 2-fluoroacrylate. We reported herein the efficient ruthenium-catalyzed CM reaction of various terminal and internal alkenes with methyl 2-fluoroacrylate giving access, for the first time, to trisubstituted fluoroalkenes stereoselectively. Unprecedent TON for CM involving fluoroalkene, up to 175, have been obtained and the reaction proved to be tolerant and effective with a large range of olefin partners giving fair to high yields in metathesis products. (Figure presented.).
- Nouaille, Augustin,Pannecoucke, Xavier,Poisson, Thomas,Couve-Bonnaire, Samuel
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p. 2140 - 2147
(2021/03/06)
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- Visible Light/Tertiary Amine Promoted Synergistic Hydroxydifluoroacetamidation of Unactivated Alkenes under Air
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An efficient and novel method for regioselective hydroxydifluoroacetamidation of alkenes with bromodifluoroacetamides has been achieved via a tandem radical pathway mediated by photoredox catalysis under metal-free conditions. This transformation proceeded smoothly in the presence of Rhodamine 6G, affording a series of α,α-difluoro-γ-hydroxyacetamides in moderate to excellent yields. The significant advantages of this protocol are the low-cost photocatalyst, readily available starting materials, synthetic convenience, and wide functional group compatibility.
- Huang, Panyi,Jin, Can,Shi, Xiayue,Sun, Bin,Yan, Zhiyang,Yu, Chuanming,Zhu, Rui,Zhuang, Xiaohui
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supporting information
p. 617 - 622
(2021/01/13)
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- Unexpected Nickel Complex Speciation Unlocks Alternative Pathways for the Reactions of Alkyl Halides with dppf-Nickel(0)
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The mechanism of the reactions between dppf-Ni0 complexes and alkyl halides has been investigated using kinetic and mechanistic experiments and DFT calculations. The active species is [Ni(κ2-dppf)(κ1-dppf)], which undergoes a halide abstraction reaction with alkyl halides and rapidly captures the alkyl radical that is formed. The rates of the reactions of [Ni(COD)(dppf)] with alkyl halides and the yields of prototypical nickel-catalyzed Kumada cross-coupling reactions of alkyl halides are shown to be significantly improved by the addition of free dppf ligand.
- Greaves, Megan E.,Lloyd-Jones, Guy C.,Maseras, Feliu,Nelson, David J.,Ronson, Thomas O.,Sproules, Stephen
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p. 10717 - 10725
(2020/11/09)
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- CuPd Nanoparticles as a Robust Catalyst for Electrochemical Allylic Alkylation
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An efficient CuPd nanoparticle (NP) catalyst (3 nm CuPd NPs deposited on carbon support) is designed for catalyzing electrochemical allylic alkylation in water/isopropanol (1:1 v/v) and 0.2 m KHCO3 solution at room temperature. The Pd catalysis was Pd/Cu composition-dependent, and CuPd NPs with a Pd/Cu ratio close to one are the most efficient catalyst for the selective cross-coupling of alkyl halides and allylic halides to form C?C hydrocarbons with product yields reaching up to 99 %. This NP-catalyzed electrochemical allylic alkylation expands the synthetic scope of cross-coupling reactions and can be further extended to other organic reaction systems for developing green chemistry electrosynthesis methods.
- Guo, Xuefeng,Lin, Honghong,Muzzio, Michelle,Pang, Huan,Shen, Mengqi,Sun, Shouheng,Wei, Kecheng,Williard, Paul,Yin, Zhouyang,Yu, Chao
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supporting information
p. 15933 - 15936
(2020/07/04)
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- Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis
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Migratory functionalization of alkenes has emerged as a powerful strategy to achieve functionalization at a distal position to the original reactive site on a hydrocarbon chain. However, an analogous protocol for alkyne substrates is yet to be developed. Herein, a base and cobalt relay catalytic process for the selective synthesis of (Z)-2-alkenes and conjugated E alkenes by migratory hydrogenation of terminal alkynes is disclosed. Mechanistic studies support a relay catalytic process involving a sequential base-catalyzed isomerization of terminal alkynes and cobalt-catalyzed hydrogenation of either 2-alkynes or conjugated diene intermediates. Notably, this practical non-noble metal catalytic system enables efficient control of the chemo-, regio-, and stereoselectivity of this transformation.
- Liu, Bingxue,Liu, Qiang,Liu, Xufang
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supporting information
p. 6750 - 6755
(2020/03/13)
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- General C(sp2)-C(sp3) Cross-Electrophile Coupling Reactions Enabled by Overcharge Protection of Homogeneous Electrocatalysts
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Cross-electrophile coupling (XEC) of alkyl and aryl halides promoted by electrochemistry represents an attractive alternative to conventional methods that require stoichiometric quantities of high-energy reductants. Most importantly, electroreduction can readily exceed the reducing potentials of chemical reductants to activate catalysts with improved reactivities and selectivities over conventional systems. This work details the mechanistically-driven development of an electrochemical methodology for XEC that utilizes redox-active shuttles developed by the energy-storage community to protect reactive coupling catalysts from overreduction. The resulting electrocatalytic system is practical, scalable, and broadly applicable to the reductive coupling of a wide range of aryl, heteroaryl, or vinyl bromides with primary or secondary alkyl bromides. The impact of overcharge protection as a strategy for electrosynthetic methodologies is underscored by the dramatic differences in yields from coupling reactions with added redox shuttles (generally >80%) and those without (generally 20%). In addition to excellent yields for a wide range of substrates, reactions protected from overreduction can be performed at high currents and on multigram scales.
- Hamby, Taylor B.,Sevov, Christo S.,Truesdell, Blaise L.
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supporting information
p. 5884 - 5893
(2020/04/10)
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- Cobalt-Catalyzed Migrational Isomerization of Styrenes
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An efficient cobalt-catalyzed migrational isomerization of styrenes was developed using the thiazoline iminopyridine (TIP) ligand. This reaction is operationally simple and atom-economical using readily available starting materials to access trisubstituted alkenes. Even when using a 0.1 mol % catalyst loading, the reaction could be conducted in neat and completed in 1 h with excellent conversion and high E stereoselectivity.
- Zhao, Jiajin,Cheng, Biao,Chen, Chenhui,Lu, Zhan
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supporting information
p. 837 - 841
(2020/01/31)
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- Iron-catalyzed AlkylAlkyl negishi coupling of organoaluminum reagents
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The first iron-catalyzed cross-coupling reaction of alkyl halides with alkylaluminum reagents (alkylalkyl Negishi coupling) is developed using an iron/bisphosphine catalyst system. The reaction shows high functional group tolerance: various primary alkyl halides possessing a non-protected indole, carboxyl, or hydroxy group are coupled with primary alkylaluminum reagents in good yields. Potassium fluoride plays a key role to promote the reaction by generating an aluminate species, which facilitates the transmetalation between the organoaluminum and the iron catalyst.
- Agata, Ryosuke,Kawamura, Shintaro,Isozaki, Katsuhiro,Nakamura, Masaharu
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supporting information
p. 238 - 241
(2019/03/13)
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- Controllable, Sequential, and Stereoselective C-H Allylic Alkylation of Alkenes
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The direct conversion of C-H bonds into new C-C bonds represents a powerful approach to generate complex molecules from simple starting materials. However, a general and controllable method for the sequential conversion of a methyl group into a fully substituted carbon center remains a challenge. We report a new method for the selective and sequential replacement of three C-H bonds at the allylic position of propylene and other simple terminal alkenes with different carbon groups derived from Grignard reagents. A copper catalyst and electron-rich biaryl phosphine ligand facilitate the formation of allylic alkylation products in high branch selectivity. We also present conditions for the generation of enantioenriched allylic alkylation products in the presence of catalytic copper and a chiral phosphine ligand. With this approach, diverse and complex products with substituted carbon centers can be generated from simple and abundant feedstock chemicals.
- Qin, Ling,Sharique, Mohammed,Tambar, Uttam K.
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p. 17305 - 17313
(2019/11/03)
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- Palladium-catalyzed tandem isomerization/hydrothiolation of allylarenes
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Herein we report a tandem olefin migration/hydrothiolation of allyl benzenes facilitated by an in situ generated palladium hydride. A catalyst system composed of palladium acetate and bidentate ligand dtbpx (1,2-bis(di-tert-butylphosphinomethyl)benzene in the presence of catalytic amounts of triflic acid led to the tandem transformation, which furnished benzylic thioethers. The reaction exhibits high regioselectivity and can be conducted under mild conditions. The robustness of the catalyst is displayed through reactions with coordinating thiols.
- Kathe, Prasad M.,Fleischer, Ivana
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supporting information
p. 2213 - 2217
(2019/03/26)
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- Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
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We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
- Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
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supporting information
p. 5723 - 5728
(2019/04/03)
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- Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
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Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Li, Chen-Chen,Ung, Sosthene,Gao, Jian,Li, Chao-Jun
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supporting information
p. 16520 - 16524
(2018/11/23)
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- Iron-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Unactivated Arylboronic Esters
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An iron-catalyzed cross-coupling reaction between alkyl halides and arylboronic esters was developed that does not involve activation of the boronic ester with alkyllithium reagents nor requires magnesium additives. A combination of experimental and theoretical investigations revealed that lithium amide bases coupled with iron complexes containing deprotonated cyanobis(oxazoline) ligands were best to obtain high yields (up to 89%) in catalytic cross-coupling reactions. Mechanistic investigations implicate carbon-centered radical intermediates and highlight the critical importance of avoiding conditions that lead to iron aggregates. The new iron-catalyzed Suzuki-Miyaura reaction was applied toward the shortest reported synthesis of the pharmaceutical Cinacalcet.
- Crockett, Michael P.,Tyrol, Chet C.,Wong, Alexander S.,Li, Bo,Byers, Jeffery A.
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supporting information
p. 5233 - 5237
(2018/09/12)
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- Synthesis of Aryl C-Glycosides via Iron-Catalyzed Cross Coupling of Halosugars: Stereoselective Anomeric Arylation of Glycosyl Radicals
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We have developed a novel diastereoselective iron-catalyzed cross-coupling reaction of various glycosyl halides with aryl metal reagents for the efficient synthesis of aryl C-glycosides, which are of significant pharmaceutical interest due to their biological activities and resistance toward metabolic degradation. A variety of aryl, heteroaryl, and vinyl metal reagents can be cross-coupled with glycosyl halides in high yields in the presence of a well-defined iron complex, composed of iron(II) chloride and a bulky bisphosphine ligand, TMS-SciOPP. The chemoselective nature of the reaction allows the use of synthetically versatile acetyl-protected glycosyl donors and the incorporation of various functional groups on the aryl moieties, producing a diverse array of aryl C-glycosides, including Canagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), and a prevailing diabetes drug. The cross-coupling reaction proceeds via generation and stereoselective trapping of glycosyl radical intermediates, representing a rare example of highly stereoselective carbon-carbon bond formation based on iron catalysis. Radical probe experiments using 3,4,6-tri-O-acetyl-2-O-allyl-α-d-glucopyranosyl bromide (8) and 6-bromo-1-hexene (10) confirm the generation and intermediacy of the corresponding glycosyl radicals. Density functional theory (DFT) calculations reveal that the observed anomeric diastereoselectivity is attributable to the relative stability of the conformers of glycosyl radical intermediates. The present cross-coupling reaction demonstrates the potential of iron-catalyzed stereo- and chemoselective carbon-carbon bond formation in the synthesis of bioactive compounds of certain structural complexity.
- Adak, Laksmikanta,Kawamura, Shintaro,Toma, Gabriel,Takenaka, Toshio,Isozaki, Katsuhiro,Takaya, Hikaru,Orita, Akihiro,Li, Ho C.,Shing, Tony K. M.,Nakamura, Masaharu
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p. 10693 - 10701
(2017/08/15)
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- Palladium-Catalyzed Electrochemical Allylic Alkylation between Alkyl and Allylic Halides in Aqueous Solution
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A new route for the direct cross-coupling of alkyl and allylic halides using electrochemical technique has been developed in aqueous media under air. Catalyzed by Pd(OAc)2, the Zn-mediated allylic alkylations proceed smoothly between a full range of alkyl halides (primary, secondary, and tertiary) and substituted allylic halides. Protection-deprotection of acidic hydrogen in the substrates is avoided.
- Lai, Yin-Long,Huang, Jing-Mei
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supporting information
p. 2022 - 2025
(2017/04/28)
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- Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
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Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
- Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
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p. 1996 - 2003
(2017/02/26)
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- Mechanistic Studies of Catalytic Carbon-Carbon Cross-Coupling by Well-Defined Iron NHC Complexes
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The mechanism of iron-catalyzed carbon-carbon cross-coupling reactions between Grignard reagents and alkyl halides has been investigated using well-defined N-heterocyclic carbene (NHC) compounds. The iron(II) precatalyst, [Fe2Cl2(μ-Cl)2(IPr)2], was employed in several C-C cross coupling reactions exhibiting the ability to efficiently couple primary and secondary alkyl halides with several aryl and alkyl Grignard reagents. For selected substrates, a 2 mol % catalyst loading (4 mol % Fe) afforded conversions of >99% and were achieved with 8% homocoupling of the electrophile. The mechanism of the coupling reaction was studied by means of radical clock, radical trap, and single-turnover experiments, which support a radical-based cycle involving an Fe(II/III) redox couple. The implications of this mechanism on the efficacy of iron-NHC-catalyzed cross-coupling reactions are discussed.
- Przyojski, Jacob A.,Veggeberg, Kevin P.,Arman, Hadi D.,Tonzetich, Zachary J.
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p. 5938 - 5946
(2015/10/12)
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- Copper-Catalyzed Cross-Coupling Reaction of Allyl Boron Ester with 1°/2°/3°-Halogenated Alkanes
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The cross-coupling reaction of allyl boron ester with 1°/2°/3°-halogenated alkanes in the presence of copper has been developed for the first time, which provides a mild and efficient method for the construction of saturated C(sp3)-C(sp3) bonds. This protocol shows excellent compatibility with the nonactivated primary, secondary, and even tertiary halogenated alkanes under mild conditions.
- Wang, Guang-Zu,Jiang, Jian,Bu, Xiao-Song,Dai, Jian-Jun,Xu, Jun,Fu, Yao,Xu, Hua-Jian
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supporting information
p. 3682 - 3685
(2015/08/18)
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- Iron pincer complexes as catalysts and intermediates in alkyl-aryl kumada coupling reactions
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Iron-catalyzed alkyl-aryl Kumada coupling has developed into an efficient synthetic method, yet its mechanism remains vague. Here, we apply a bis(oxazolinylphenyl)amido pincer ligand (Bopa) to stabilize the catalytically active Fe center, resulting in isolation and characterization of well-defined iron complexes whose catalytic roles have been probed and confirmed. Reactivity studies of the iron complexes identify an Fe(II) "ate" complex, [Fe(Bopa-Ph)(Ph)2]-, as the active species for the oxidative addition of alkyl halide. Experiments using radical-probe substrates and DFT computations reveal a bimetallic and radical mechanism for the oxidative addition. The kinetics of the coupling of an alkyl iodide with PhMgCl suggests that formation of the "ate" complex, rather than oxidative addition, is the turnover-determining step. This work provides insights into iron-catalyzed cross-coupling reactions of alkyl halides.
- Bauer, Gerald,Wodrich, Matthew D.,Scopelliti, Rosario,Hu, Xile
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supporting information
p. 289 - 298
(2015/01/30)
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- Expedient iron-catalyzed coupling of alkyl, benzyl and allyl halides with arylboronic esters
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While attractive, the iron-catalyzed coupling of arylboron reagents with alkyl halides typically requires expensive or synthetically challenging diphosphine ligands. Herein, we show that primary and secondary alkyl bromides and chlorides, as well as benzyl and allyl halides, can be coupled with arylboronic esters, activated with alkyllithium reagents, by using very simple iron-based catalysts. The catalysts used were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)3] with no added co- ligands. In the former case, preliminary mechanistic studies highlight the likely involvement of iron(I)-phosphine intermediates. More irons in the fire: Primary and secondary alkyl, benzyl and allyl halides were coupled with arylboronic esters by using very simple iron-based catalysts. These were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)3] with no added co-ligands (see scheme; acac=acetylacetonate). In the former case, preliminary mechanistic studies highlight the likely involvement of low-coordinate iron(I)-phosphine intermediates.
- Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Carvell, Thomas W.,Cogswell, Paul M.,Gallagher, Timothy,Harvey, Jeremy N.,Murphy, Damien M.,Neeve, Emily C.,Nunn, Joshua,Pye, Dominic R.
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supporting information
p. 7935 - 7938
(2014/07/07)
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- Mechanism and selectivity in nickel-catalyzed cross-electrophile coupling of aryl halides with alkyl halides
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The direct cross-coupling of two different electrophiles, such as an aryl halide with an alkyl halide, offers many advantages over conventional cross-coupling methods that require a carbon nucleophile. Despite its promise as a versatile synthetic strategy, a limited understanding of the mechanism and origin of cross selectivity has hindered progress in reaction development and design. Herein, we shed light on the mechanism for the nickel-catalyzed cross-electrophile coupling of aryl halides with alkyl halides and demonstrate that the selectivity arises from an unusual catalytic cycle that combines both polar and radical steps to form the new C-C bond.
- Biswas, Soumik,Weix, Daniel J.
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supporting information
p. 16192 - 16197
(2013/11/19)
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- Synthesis of iron(III) complex bearing tridentate β-Aminoketonato Ligand: Application to iron-catalyzed cross-coupling reaction of arylmagnesium bromides with alkyl halides
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A tridentate β-aminoketonato iron complex was prepared by the reaction of lithium β-aminoketonato with FeCl3. This iron complex was found to be an efficient catalyst for the crosscoupling reaction between arylmagnesium bromides and alkyl halides.
- Yamaguchi, Yoshitaka,Ando, Hiroaki,Nagaya, Makoto,Hinago, Hideto,Ito, Takashi,Asami, Masatoshi
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supporting information; experimental part
p. 983 - 985
(2011/12/05)
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- Regioselective semihydrogenation of dienes
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A one-pot, three-step strategy for the regioselective semihydrogenation of dienes is described. This procedure uses 9-BBN-H as a temporary protective group for alkenes. Yields range from 55% to 95%, and the reaction is tolerant of a variety of common functional groups. Additionally, the final elimination step of the sequence can be replaced with a peroxide-mediated alkylborane oxidation, generating regioselectively semihydrogenated product alcohols.
- Graham, Thomas J. A.,Poole, Thomas H.,Reese, Charles N.,Goess, Brian C.
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experimental part
p. 4132 - 4138
(2011/07/07)
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- Copper-catalyzed cross-coupling reaction of organoboron compounds with primary alkyl halides and pseudohalides
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Non-activated alkyl electrophiles, including alkyl iodides, bromides, tosylates, mesylates, and even chlorides, underwent copper-catalyzed cross-coupling with aryl boron compounds and alkyl 9-BBN reagents (see scheme; 9-BBN=9-borabicyclo[3.3.1]nonane). The reactions proceed with practically useful reactivities and thus complement palladium- and nickel-catalyzed Suzuki-Miyaura coupling reactions of alkyl halides.
- Yang, Chu-Ting,Zhang, Zhen-Qi,Liu, Yu-Chen,Liu, Lei
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p. 3904 - 3907
(2011/05/15)
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- Synthesis and characterization of substituted polynorbornene derivatives
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This paper describes palladium (II) catalyst based synthesis and detailed characterization of vinyl-type polynorbornenes (PNBs) with bulky phenyl, adamantane, or norbornane substituents linked by ester, ether, or alkyl bridges. The structure-property relationships of the substituted PNBs were investigated concerning the thermal stability, glass transition temperature, wide-angle X-ray scattering (WAXS) patterns, mechanical properties, and dielectric characteristics. PNBs with phenyl substituted pendant groups improved the solubility and film forming properties due to aromatic-aromatic interactions. The substituted PNBs exhibited good thermal and thermo-mechanical properties with thermal decomposition temperature (Td,5%) above 300 °C and glass transition temperature in the range of 134-325 °C.WAXS studies revealed the presence of local nano-scale order in the noncrystalline state, especially in ester bridged adamantane and norbornane substituted polymers, probably due to the steric packing requirements of bulky side groups coupled with dipolar interactions. Nanoindentation results showed high modulus (6.5-7.9 GPa) and hardness (0.11-0.38 GPa) for PNBs with diester adamantane and norbornane substituted polymers. Excellent dielectric properties with a dielectric constant (ε) of 2.5 and a dielectric loss tangent (tan δ) of 0.0005 were measured for poly [2-(4-phenylbutyl)-5-norbornene] at 1 GHz, rendering it very attractive for interconnect dielectric films in high-frequency electronic devices.
- Mulpuri, Syamkumar V.,Shin, Jinbok,Shin, Boo-Gyo,Yoon, Do Y.,Greiner, Andreas
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p. 4377 - 4386,10
(2012/12/12)
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- Ligand effects in chromium diphosphine catalysed olefin co-trimerisation and diene trimerisation
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A series of symmetric and unsymmetric N,N-bis(diarylphosphino)amine ('PNP') ligands (Ar2PN(R)PNAr′2: R = Me, Ar2 = o-anisyl, Ar′2 = Ph, 1, R = Me, Ar2 = o-tolyl, Ar′2 = Ph, 2, R = Me, Ar2 = Ph(o-ethyl), Ar′2 = Ph, 3, R = Me, Ar2 = Ar′2 = o-anisyl, 4, R = iPr, Ar2 = Ar′2 = Ph, 5) and symmetric N,N′-bis(diarylphosphino)dimethylhydrazine ('PNNP') ligands (Ar2PN(Me)N(Me)PAr2: Ar2 = o-tolyl, 6, Ar 2 = o-anisyl, 7) have been synthesised. Catalytic screening for ethene/styrene co-trimerisation and isoprene trimerisation was performed via the in situ complexation to [CrCl3(THF)3] followed by activation with methylaluminoxane (MAO). PNNP catalytic systems showed a significant increase in activity and selectivity over previously reported PNP systems in isoprene trimerisation. Comparing the symmetric and unsymmetric variants in ethene and styrene co-trimerisation resulted in a switch in selectivity, an unsymmetric catalytic (o-anisyl)2PN(Me)PPh 2 (1) ligand system affording unique incorporation of two styrenic monomers into the co-trimer product distribution differing from the familiar two ethene and one styrene ω-substituted alkenes. Complexes of the type [(diphosphine)Cr(CO)4] 8-11 were also synthesised, the single-crystal X-ray diffraction of which are reported. We propose the mechanisms of these catalytic transformations and an insight into the effect of the ligand series on the chromacyclic catalytic intermediates. The Royal Society of Chemistry.
- Bowen, Lucy E.,Charernsuk, Manutsavin,Hey, Thomas W.,McMullin, Claire L.,Orpen, A. Guy,Wass, Duncan F.
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experimental part
p. 560 - 567
(2010/04/03)
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- Nanocage catalysts - Rhodium nanoclusters encapsulated with dendrimers as accessible and stable catalysts for olefin and nitroarene hydrogenations
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The phenylazomethine dendrimer generation 4 (TPP-DPA G4) and polyamidoamine dendrimer (PAMAM G4-OH) encapsulating rhodium nanocluster were found to be highly effective for olefin and nitroarene hydrogenations, affording high TOF (up to 17520 h-1); the important feature of the nanocage catalyst is that substrates can pass through the branches of the protecting groups of nanoclusters without releasing nanoclusters from the dendrimer. The Royal Society of Chemistry.
- Nakamula, Ikuse,Yamanoi, Yoshinori,Yonezawa, Tetsu,Imaoka, Takane,Yamamoto, Kimihisa,Nishihara, Hiroshi
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supporting information; experimental part
p. 5716 - 5718
(2009/04/13)
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- First stereoselective total synthesis of (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran- 2-one
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A stereoselective total synthesis of (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran- 2-one is reported. The strategy utilizes an iterative Jacobsen hydrolytic kinetic resolution, ring opening with a chiral propargylic synthon and
- Radha Krishna, Palakodety,Srinivas, Ravula
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p. 2013 - 2015
(2007/10/03)
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- Simple iron-amine catalysts for the cross-coupling of aryl Grignards with alkyl halides bearing β-hydrogens
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Mixtures of iron(III) chloride and appropriate amine ligands are active catalysts for the coupling of aryl Grignard reagents with primary and secondary alkyl halide substrates bearing β-hydrogens, under mild and simple reaction conditions. The Royal Society of Chemistry 2005.
- Bedford, Robin B.,Bruce, Duncan W.,Frost, Robert M.,Hird, Michael
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p. 4161 - 4163
(2007/10/03)
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- Cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic and benzylic grignard reagents and their application to tandem radical cyclization/cross-coupling reactions
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Details of cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic Grignard reagents are disclosed. A combination of cobalt(II) chloride and 1,2-bis(diphenylphosphino)ethane (DPPE) or 1,3-bis(diphenylphosphino)propane (DPPP) is suitable as a precatalyst and allows secondary and tertiary alkyl halides-as well as primary ones-to be employed as coupling partners for allyl Grignard reagents. The reaction offers a facile synthesis of quaternary carbon centers. which has practically never been possible with palladium, nickel, and copper catalysts. Benzyl, methallyl, and crotyl Grignard reagents can all couple with alkyl halides. The benzylation definitely requires DPPE or DPPP as a ligand. The reaction mechanism should include the generation of an alkyl radical from the parent alkyl halide. The mechanism can be interpreted in terms of a tandem radical cyclization/cross-coupling reaction. In addition, serendipitous tandem radical cyclization/cyclopropanation/carbonyl allylation of 5-alkoxy-6-halo-4-oxa-1-hexene derivatives is also described. The intermediacy of a carbon-centered radical results in the loss of the original stereochemistry of the parent alkyl halides, creating the potential for asymmetric cross-coupling of racemic alkyl halides.
- Ohmiya, Hirohisa,Tsuji, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
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p. 5640 - 5648
(2007/10/03)
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- Iron-Catalyzed Cross-Coupling of Primary and Secondary Alkyl Halides with Aryl Grignard Reagents
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An iron-catalyzed cross-coupling reaction of a primary or secondary alkyl halide with an aryl Grignard reagent proceeds under mild conditions to give the corresponding coupling product in quantitative yield. Copyright
- Nakamura, Masaharu,Matsuo, Keiko,Ito, Shingo,Nakamura, Eiichi
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p. 3686 - 3687
(2007/10/03)
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- Rapid defunctionalization of carbonyl group to methylene with polymethylhydrosiloxane-B(C6F5)3
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The polymethylhydrosiloxane-B(C6F5)3 combination is found to be a versatile carbonyl defunctionalization system under mild and rapid conditions. For the first time, B(C6F5)3 has been used as a nonconventional Lewis acid catalyst to activate PMHS. Aromatic and aliphatic carbonyl compounds were effectively reduced to give the corresponding alkanes in high yields.
- Chandrasekhar,Raji Reddy, Ch.,Nagendra Babu
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p. 9080 - 9082
(2007/10/03)
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- Generation of allylic manganates from trimethylmanganate and allylic stannanes and their reactions with epoxides
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A new method for forming allyldimethylmanganate has been developed. The preparation eliminated the need for prior generation of an allylmetal species such as allyllithium or allylmagnesium compounds. The reagents reacted with epoxides to give allylated products exclusively in good yields.
- Tang, Jun,Yorimitsu, Hideki,Kakiya, Hirotada,Inoue, Rie,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 9019 - 9022
(2007/10/03)
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- Synthesis of Organolithium Compounds from Phenyl Selenides
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Alkyl aryl selenides react with lithium arenides to produce, regioselectively, alkyllithiums and lithium arylselenolates.Experimental conditions, especially the temperature, have a profound effect on the course of this reaction and on the nature of the products.
- Krief, Alain,Nazih, Abdesslame,Hobe, Myriam
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p. 8111 - 8114
(2007/10/02)
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- Photocleavage of Benzyl-Sulfide Bonds
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The nucleoside transport inhibitor 6--9-(β-D-ribofuranosyl)purine, NBMPR, has been used successfully in photoaffinity labeling.We have studied the mechanism for photocleavage of the benzyl-sulfur bond by using substituted benzyl phenyl sulfides as analogues of NBMPR.This has enabled us to enhance the photoreactivity of the benzyl-sulfur bond.We have also performed "radical clock" studies with a hexenyl side chain to trap reactive intermediates.The mechanistic interpretation from the substituent and side chain studies is that the benzyl-sulfur moiety is photocleaved via a homolytic pathway.
- Fleming, Steven A.,Jensen, Anton W.
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p. 7135 - 7137
(2007/10/02)
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- The importance of conformation in the reactivity of radical cations. Changing configuration at saturated carbon centres
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Irradiation of an acetonitrile solution of cis-1-methyl-2-phenylcyclopentane (1b cis); 1,4-dicyanobenzene (2), an electron-accepting photosensitizer; and 2,4,6-collidine (3), a nonnucleophilic base, leads to configurational isomerization of the cyclopenta
- Perrott, Allyson L.,Arnold, Donald R.
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p. 272 - 279
(2007/10/02)
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- RADICAL-ANIONS OF AROMATIC COMPOUNDS. XVII. REACTION OF BENZONITRILE RADICAL-ANION WITH ALKYL HALIDES IN LIQUID AMMONIA
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The main products from the reaction of the potassium salt of the benzonitrile radical-anion with normal alkyl halides (butyl chloride, butyl bromide, butyl iodide, and octyl bromide) in liquid ammonia are the corresponding alkylbenzenes.A small amount of 1-cyano-1-butyl-2,5-cyclohexadiene is also formed in the reactions with butyl iodide and with an excess of butyl bromide.In the reaction of the benzonitrile-4d radical-anion and octyl bromide octyl benzene-4d is formed in an amount corresponding to entry of the alkyl fragment at the ipso position in relation to the cyano group to the extent of not less than 95percent.With cyclopropylmethyl bromide as model it was established that the benzonitrile radical-anion acts as a nucleophile in reaction with alkyl halides.
- Bilkis, I. I.,Vaganova, T. A.,Bobyleva, V. I.,Shteingarts, V. D.
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- Aromatic annulation with naphtho[1,8-de]-1,3-dithiin carbocations
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The title carbocations have been produced by the reaction of silver trifluoromethanesulfonate with mixed orthothioesters. Intramolecular aromatic electrophilic substitution (annulation) of the cationic intermediates proceeds readily and provides an efficient, chemoselective route for appending six-membered rings to nonactivated aromatic systems.
- Gamage, Swarna A.,Smith, Robin A. J.
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p. 2111 - 2128
(2007/10/02)
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- Occurrence of Electron Transfer in the Reduction of Organic Halides by LiAlH4 and AlH3
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A variety of methods have been utilized to detect the occurrence of a single electron transfer pathway in the reduction of alkyl halides by LiAlH4 and AlH3, i.e., (1) product studies of reduction of cyclizable alkyl halides containing the 5-hexenyl group, (2) trapping of intermediate radicals by dicyclohexylphosphine and other trapping agents, (3) direct EPR observation of the trityl radical in the reduction of trityl bromide, and (4) stereochemical studies of the reduction of secondary halides by lithium aluminum deuteride.The extent of electron transfer was found to be a function of the solvent, the substrate, the leaving group, and the hydride reagent.For alkyl iodides, and to a lesser extent bromides, electron transfer was found to be the major reaction pathway; however, no evidence for electron transfer was found for the corresponding chlorides or tosylates.Reduction of (+)-2-octyl iodide by LiAlD4 was found to be much less stereospecific than the corresponding reduction of bromide, chloride, or tosylate, indicating intermediate radical formation in the reduction of the secondary iodide.
- Ashby, E. C.,DePriest, R. N.,Goel, A. B.,Wenderoth, Bernd,Pham, Tung N.
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p. 3545 - 3556
(2007/10/02)
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- Synthesis and Complex Formation of Phenyl- and (4-Phenylbutyl)-substituted Crown Ethers
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A number of phenyl and (4-phenylbutyl) derivates of 18-C-6 and 24-C-8 have been prepared: tetraphenyl-diene-18-crown-6 (TPDE-18-C-6), tetraphenyl-18-crown-6 (TP-18-C-6), tetraphenyldiene-24-crown-8 (TPDE-24-C-8), tetraphenyl-24-crown-8 (TP-24-C-8), and bis(4-phenylbutyl)-18-crown-6 (BPB-18-C-6).The ring formation reactions have been carried out by phase-transfer catalysis.All compounds are solids at room temperature except for the liquid BPB-18-C-6 wich represents a mixture of isomers.The syn- and anti-isomers of TP-18-C-6 and TP-24-C-8 have been isolated and identified by x-ray diffraction.The complex formation constants, determined by d. c. polarography in methanol/benzene (80:20 v/v), depend not only on the ring size but also on the number and kind of substituents as well as their steric arrangement.The derivatives of 18-C-6 form the most stable complexes with K+, Sr2+, Ba2+, and Pb2+.The derivatives of 24-C-8 prefer K+, Rb+, and Ba2+.
- Blasius, Ewald,Rausch, Ralf Andreas,Andreetti, Giovanni Dario,Rebizant, Jean
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p. 1113 - 1127
(2007/10/02)
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