- The copper-catalyzed ring-opening reactions of cyclopropanes by N-fluorobenzenesulfonimide toward N-allylsulfonamides
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In this paper, we reported a copper-catalyzed ring-opening reaction of arylcyclopropanes by N-fluorobenzenesulfonimide, leading to N-allylsulfonamides in moderate to good yields. This procedure tolerated bromo, fluoro, trifluoromethyl, phenyl and alkyl groups in the phenyl, proceeding with a sequential ring-opening of arylcyclopropanes, and copper-mediated β-H elimination of alkyl radical.
- Zhou, Aijun,Shao, Ying,Chen, Fan,Qian, Peng-Cheng,Cheng, Jiang
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supporting information
(2022/01/03)
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- Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations
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Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.
- Svec, Riley L.,Hergenrother, Paul J.
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supporting information
p. 1857 - 1862
(2019/12/27)
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- Silylium-Ion-Promoted Ring-Opening Hydrosilylation and Disilylation of Unactivated Cyclopropanes
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A silylium-ion-promoted ring-opening hydrosilylation of unactivated cyclopropanes is reported. The reaction is facilitated by the γ-silicon effect, and the regioselectivity is influenced by various stabilizing effects on the carbenium-ion intermediates, including the β-silicon effect. The experimental observations are in accord with the computed reaction mechanism. The work also showcases the ability of silylium ions to isomerize cyclopropyl to allyl groups, and the resulting α-olefins engage in a silylium-ion-mediated disilylation with hexamethyldisilane.
- Bonetti, Vittorio,Klare, Hendrik F. T.,Oestreich, Martin,Roy, Avijit,Wang, Guoqiang,Wu, Qian
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supporting information
(2020/02/04)
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- Intermolecular Electrophilic Bromoesterification and Bromoetherification of Unactivated Cyclopropanes
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1,3-difunctionalization of cyclopropane is an useful organic transformation. The corresponding 1,3-difunctionalized products are synthetic synthons and building blocks in many organic syntheses. Many existing ring-opening difunctionalization methodologies rely primarily on the use of donor?acceptor cyclopropanes, while the difunctionalization of unactivated cyclopropanes is less exploited. In this research, 1,3-bromoesterification and 1,3-bromoetherification of unactivated cyclopropanes were successfully achieved using N-bromosuccinimide as the brominating agent with high yields and regioselectivity. (Figure presented.).
- Leung, Vincent Ming-Yau,Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 2039 - 2044
(2020/04/20)
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- Lewis Base-Promoted Ring-Opening 1,3-Dioxygenation of Unactivated Cyclopropanes Using a Hypervalent Iodine Reagent
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A facile and effective system has been developed for the regio- and chemoselective ring-opening/electrophilic functionalization of cyclopropanes through C?C bond activation by [bis(trifluoroacetoxy)iodo]benzene with the aid of the Lewis basic promoter p-toluenesulfonamide. The p-toluenesulfonamide-promoted system works well for a wide range of cyclopropanes, resulting in the formation of 1,3-diol products in good yields and regioselectivity.
- Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 3782 - 3786
(2018/03/13)
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- Aminofluorination of Cyclopropanes: A Multifold Approach through a Common, Catalytically Generated Intermediate
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We have discovered a highly regioselective aminofluorination of cyclopropanes. Remarkably, four unique sets of conditions-two photochemical, two purely chemical-generated the same aminofluorinated adducts in good to excellent yields. The multiple, diverse ways in which the reaction could be initiated provided valuable clues that led to the proposal of a "unifying" chain propagation mechanism beyond initiation, tied by a common intermediate. In all, the proposed mechanism herein is substantiated by product distribution studies, kinetic analyses, LFERs, Rehm-Weller estimations of ΔGET, competition experiments, KIEs, fluorescence data, and DFT calculations. From a more physical standpoint, transient-absorption experiments have allowed direct spectroscopic observation of radical ion intermediates (previously only postulated or probed indirectly in photochemical fluorination systems) and, consequently, have provided kinetic support for chain propagation. Lastly, calculations suggest that solvent may play an important role in the cyclopropane ring-opening step.
- Pitts, Cody Ross,Ling, Bill,Snyder, Joshua A.,Bragg, Arthur E.,Lectka, Thomas
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supporting information
p. 6598 - 6609
(2016/06/09)
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- Cyclopropanation of styrenes and stilbenes using lithiomethyl trimethylammonium triflate as methylene donor
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Lithiomethyl trimethylammonium triflate, prepared from tetramethylammonium triflate, cyclopropanates several styrenes and stilbenes with electron-donating and selected electron-withdrawing substituents efficiently. Kinetic data support a stepwise nucleophilic addition-ring closure mechanism for this methylenation. This journal is the Partner Organisations 2014.
- Sarria Toro, Juan M.,Den Hartog, Tim,Chen, Peter
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supporting information
p. 10608 - 10610
(2014/10/15)
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- Diels-Alder reactions for the construction of cyclopropylarenes
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The straightforward synthesis of new bicyclopropyl-substituted alkynes and 1,3-dienes and their application in cobalt-catalyzed Diels-Alder reactions are described. The cycloaddition processes generated the desired bicyclopropyl-substituted arene derivatives in moderate to good yields, depending on the steric congestion of the reaction partners. The regioselectivity of the cycloaddition was controlled by the ligand coordinated to the cobalt center. The cyclopropyl moiety remained unchanged over the course of the Diels-Alder reaction, indicating that no radical type intermediates were formed. Only in a single case did the DDQ oxidation of the primarily formed dihydroaromatic product lead to ring opening of a cyclopropyl subunit. In all of the other cases, cyclopropyl-modified arenes with various functionalities were obtained. Copyright
- Arndt, Marion,Hilt, Gerhard,Khlebnikov, Alexander F.,Kozhushkov, Sergei I.,De Meijere, Armin
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experimental part
p. 3112 - 3121
(2012/07/14)
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- Lanthanum metal-assisted cyclopropanation of alkenes with gem-dihaloalkanes
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It was confirmed that lanthanum metal was an efficient reagent for the reductive dehalogenation of gem-dihaloalkanes. When gem-dihaloalkanes were allowed to react with lanthanum metal in the presence of alkenes, cyclopropanation of the alkenes occurred under mild conditions giving the corresponding cyclopropanes in moderate to good yields.
- Nishiyama, Yutaka,Tanimizu, Hana,Tomita, Tsuyoshi
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p. 6405 - 6407
(2008/02/12)
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- Suzuki coupling of cyclopropylboronic acid with aryl halides catalyzed by a palladium-tetraphosphine complex
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The tetraphosphine all-cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)- cyclopentane (Tedicyp) in combination with [Pd(C3H 5)Cl]2 affords a very efficient catalyst for the coupling of cyclopropylboronic acid with aryl bromides and aryl chlorides. Higher reactions rates were observed with aryl bromides than with aryl chlorides; however, even in the presence of 1-0.4% of catalyst, a few aryl chlorides gave the coupling products in good yields. A wide variety of substituents such as alkyl, methoxy, trifluoromethyl, acetyl, benzoyl, formyl, carboxylate, nitro, and nitrile on the aryl halides are tolerated. The coupling reaction of sterically very congested aryl bromides such as bromomesitylene or 2,4,6-triisopropylbromobenzene also proceeds in good yields. Copyright Taylor & Francis LLC.
- Lemhadri, Mhamed,Doucet, Henri,Santelli, Maurice
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p. 121 - 128
(2007/10/03)
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- Indium-mediated, highly efficient cyclopropanation of olefins using CH 2I2 as methylene transfer reagent
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The indium-mediated, one-pot cyclopropanation of a variety of olefins with methylene iodide proceeds smoothly with excellent yields of products.
- Virender,Jain, Suman L.,Sain, Bir
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- Atom-efficient metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles
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The novel metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles is described. Triorganoindium compounds (R3In) containing alkyl, vinyl, aryl, and alkynyl groups are efficiently prepared from the correspond
- Perez,Sestelo,Sarandeses
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p. 4155 - 4160
(2007/10/03)
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- Palladium-catalyzed cross-coupling reactions of triorganoindium compounds with vinyl and aryl triflates or iodides
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(matrix presented) A novel palladium-catalyzed cross-coupling reaction of organoindium compounds with vinyl and aryl triflates or iodides is described. The reaction proceeds for alkyl-, vinyl-, alkynyl-, and arylindium compounds in excellent yields and high chemoselectivity without any excess of the organometallic. Remarkably, indium organometallics transfer efficiently the three organic groups attached to the metal.
- Perez, Ignacio,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 1267 - 1269
(2008/02/09)
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- Convenient preparation of a cyclopropanation reagent: α-Siloxymethyliron complex
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A convenient preparation of α-siloxymethyliron complex (7) was developed from commercially available s-trioxane and/or paraformaldehyde. For synthetic utility, iron methylidene complex (8) was generated in situ from the α-siloxymethyliron complex (7) and cyclopropanes (10) by treatment with alkenes.
- Du, Hong,Yang, Fukang,Mahmun Hossain
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p. 1371 - 1377
(2007/10/03)
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- The Stereochemistry of Rearrangements of Aryl and Hetaryl Groups to Primary Carbenic Centers
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The products and stereochemistries of carbenic decompositions of varied 2-aryl-1-diazoalkanes and 1-diazo-2-(2-hetaryl)propanes have been determined.
- Slack, W. E.,Taylor, W.,Moseley, C. G.,Chang, K. T.,Kraska, A.,et al.
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p. 2647 - 2650
(2007/10/02)
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- THE RATES OF DEPROTONATION OF SOME p-CYCLOPROPYLTOLUENE DERIVATIVES IN SEARCH FOR THE EFFECT OF THE CONFORMATION OF CYCLOPROPYL GROUPS ON THE STABILIZATION OF THE CARBANIONIC CENTRES
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p-Cyclopropyltoluene and 2-cyclopropylmesitylene have been prepared and the rates of base-catalyzed H-D exchange of the benzylic hydrogen atoms, para positioned with respect to the cyclopropyl group, have been compared with those of suitable model compoun
- Perkins, M. John,Peynircioglu, N. Bekir
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p. 225 - 228
(2007/10/02)
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- Regioselective Metalation of Phenylcyclopropane and Smooth Addition of 1-Phenylcyclopropyl Potassium onto Ethylene
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Whereas pentyl sodium in pentane mainly promotes a hydrogen/metal exchange reaction at the m- and p-position of phenylcyclopropane, both the butyllithium/potassium t-butoxide reagent and trimethylsilylmethyl potassium in tetrahydrofuran convert phenylcyclopropane exclusively into 1-phenylcyclopropyl potassium.The latter organometallic derivative adds smoothly onto the double bond of ethylene at temperatures around -40 deg.
- Schlosser, Manfred,Schneider, Philippe
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p. 2404 - 2410
(2007/10/02)
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