- Vinylic Organoboranes. 14. Stereospecific Synthesis of (E)-1-Halo-1-alkanes from 1-Alkynes
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The reactions of (E)-1-alkenylboronic acids and their esters and (E)-1-alkenyldibromoborane-dimethyl sulfide complexes with iodine under various conditions were investigated.All of these compounds react with iodine in the presence of base, producing (E)-1
- Brown, Herbert C.,Hamaoka, Tsutomu,Ravindran, Nair,Subrahmanyam, Chitti,Somayaji, Vishwanatha,Bhat, Narayan G.
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- Vinylic Organoboranes. 15. Mercuration of 2-Alkenyl-1,3,2-benzodioxaboroles and Boronic Acids. A Convenient Stereospecific Procedure for the Conversion of Alkynes into (E)-1-Halo-1-alkenes via Mercuric Salts
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Vinylboranes derived from terminal and internal alkynes via hydroboration with 1,3,2-benzodioxaborole undergo an instantaneous reaction with mercuric acetate at 0 deg C to give the corresponding vinylmercuric acetates in exceptionally good yields.The reac
- Brown, Herbert C.,Larock, Richard C.,Gupta, S. K.,Rajagopalan, Shyamala,Bhat, Narayan G.
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- Electrochemical Nozaki-Hiyama-Kishi Coupling: Scope, Applications, and Mechanism
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One of the most oft-employed methods for C-C bond formation involving the coupling of vinyl-halides with aldehydes catalyzed by Ni and Cr (Nozaki-Hiyama-Kishi, NHK) has been rendered more practical using an electroreductive manifold. Although early studies pointed to the feasibility of such a process, those precedents were never applied by others due to cumbersome setups and limited scope. Here we show that a carefully optimized electroreductive procedure can enable a more sustainable approach to NHK, even in an asymmetric fashion on highly complex medicinally relevant systems. The e-NHK can even enable non-canonical substrate classes, such as redox-active esters, to participate with low loadings of Cr when conventional chemical techniques fail. A combination of detailed kinetics, cyclic voltammetry, and in situ UV-vis spectroelectrochemistry of these processes illuminates the subtle features of this mechanistically intricate process.
- Baran, Phil S.,Blackmond, Donna G.,Gao, Yang,Hadt, Ryan G.,Hao, Wei,Hill, David E.,McNicholas, Brendon J.,Reisman, Sarah E.,Vantourout, Julien C.
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supporting information
p. 9478 - 9488
(2021/07/19)
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- One-Shot Radical Cross Coupling Between Benzyl Alcohols and Alkenyl Halides Using Ni/Ti/Mn System
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A “one-shot” cross coupling between benzyl alcohols and alkenyl halides has been established. A combination of low-valent Ti-mediated C?OH homolysis and the prominent chemistry of Ni-based radical catalysis afforded the desired cross-coupled product with good efficiency. The reaction proceeded regardless of the electronic property of benzyl alcohols, and Ar?B bond remained intact throughout the reaction. Alkenyl bromides with various substitution patterns were applicable to this reaction. Attempts for utilizing sterically demanding tri-substituted alkenes indicated that the steric hinderance mainly inhibited the radical-trapping by Ni species. This reaction can be a simple and efficient strategy for synthesizing densely substituted allylbenzene derivatives. (Figure presented.).
- Suga, Takuya,Takahashi, Yuuki,Ukaji, Yutaka
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supporting information
p. 5622 - 5626
(2020/10/22)
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- Practical regio- and stereoselective azidation and amination of terminal alkenes
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There is significant interest in developing more rapid and efficient production of nitrogen-containing allylic compounds, as widely used in various syntheses. This work reports a variety of allylic azides and allylic amines synthesized by an efficient, new one-pot protocol that employs readily available terminal alkenes as starting materials. This method is highly regio- and stereoselective, affording the linear (E)-isomer, under metal-free conditions. This process tolerates several functional groups including halogen-containing molecules; it is general for azides and amine nucleophiles; and, adducts were obtained in good yields.
- Ojo, Olatunji S.,Miranda, Octavio,Baumgardner, Kyle C.,Bugarin, Alejandro
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p. 9354 - 9358
(2019/01/03)
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- Formation of quaternary stereogenic centers by copper-catalyzed asymmetric conjugate addition reactions of alkenylaluminums to trisubstituted enones
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Alkenylaluminums undergo asymmetric copper-catalyzed conjugate addition (ACA) to β-substituted enones allowing the formation of stereogenic all-carbon quaternary centers. Phosphinamine-copper complexes proved to be particularly active and selective compared with phosphoramidite ligands. After extensive optimization, high enantioselectivities (up to 96 % ee) were obtained for the addition of alkenylalanes to β-substituted enones. Two strategies for the generation of the requisite alkenylaluminums were explored allowing for the introduction of aryl- and alkyl-substituted alkenyl nucleophiles. Moreover, alkyl-substituted phosphinamine (SimplePhos) ligands were identified for the first time as highly efficient ligands for the Cu-catalyzed ACA. Chiral synthesis made easy: The copper-catalyzed conjugate addition of alkenylaluminum reagents to 3-substituted cyclic enones allows for the formation of all-carbon chiral quaternary centers (see scheme; CuTC=copper(I) thiophene-2-carboxylate). Chiral phosphinamine (SimplePhos) ligands were found to be highly efficient for this transformation.
- Mueller, Daniel,Alexakis, Alexandre
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p. 15226 - 15239
(2013/11/06)
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- One-pot synthesis of telluroketene acetals and haloketene acetals using sp2 geminated hetero organobismetallic intermediates
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A novel one-pot synthesis of 1,1-dihalo-1-alkenes and 1,1-bis(butyltelluro) -1-alkenes was developed from hydrozirconation of alkynylzinc bromide with Cp2Zr(H)Cl and subsequent capture of the Zn/Zr 1,1-heterodimetallo-1- alkene intermediates wi
- Guerrero Jr., Palimécio G.,De Oliveira, Paulo R.,Baroni, Adriano C.M.,Marques, Francisco A.,Labes, Ricardo,Dabdoub, Miguel J.
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experimental part
p. 1582 - 1586
(2012/04/10)
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- Reactions of fluoroalk-1-en-1-yltrifluoroborate and perfluoroalk-1-yn-1- yltrifluoroborate salts and selected hydrocarbon analogues with hydrogen fluoride and with halogenating agents in aHF and in basic solvents
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The relative rate of the electrophilic hydrodeboration of K[R′BF 3] with HF (27-100%) diminishes in the series R′ = C 4H9CC > C4F9CFCFCC > CF 2C(CF3) > C3F7CC ~ (CF 3)2CFCC > CF3CC. When R′ = CF 3CC the new salt K[CF3CH2-CF2BF 3] was obtained by addition of HF besides CF3CCH and K[BF4]. Small amounts of water caused the formation of K[CF 3CH2-C(O)BF3] as a by-product. The electrophilic halofluorination of perfluoroalkenyltrifluoroborate salts with NCS or NBS in aHF (anhydrous HF) led to K[RFCFHal-CF2BF 3] (from K[RFCFCFBF3]) and K[R FCHal2-CF2BF3] (from K[R FCHalCFBF3] and K[RFCCBF3]) (Hal = Cl, Br). Treatment of K[RFCFCFBF3] and K[R FCCBF3] with 5% F2/N2 in MeCN gave the corresponding salts K[RFCF2-CF2BF 3] in 16-25% isolated yield. Reactions of K[trans-C4F 9CFCFBF3] with Cl2 in MeOH resulted in K[C 4F9CFCl-C(O)BF3] (major product). The latter was also obtained in reactions of K[trans-C4F9CFCFBF 3] with Cl2 in MeCN or sulfolane after sequential methanolysis of the primarily formed products. In contrast, the salts K[RCFCFBF3] (R = CnF2n+1, trans-C 4H9) and K[CF3CCBF3] underwent bromodeboration to RCFCFBr and CF3CCBr, respectively, when they were reacted with bromine in the polar solvents MeOH, MeCN, or sulfolane.
- Bardin, Vadim V.,Adonin, Nicolay Yu.,Frohn, Hermann-Josef
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experimental part
p. 114 - 128
(2012/04/10)
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- Transfer of alk-1-enyl group from boron to tin: A highly stereoselective synthesis of (E)-alk-1-enyltributylstannanes
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Treatment of (E)-alk-1-enyldicyclohexylboranes with tributyltin methoxide in the presence of galvinoxyl (1 mol%) at room temperature results in transfer of the alk-1-enyl group from boron to tin to give (E)-alk-1- enyltributylstannanes in a highly stereoselective fashion. Subsequent halodestannylation of (E)-alk-1-enyltributylstannanes is allowed to proceed in a one-pot manner to produce the corresponding (E)-1-iodoalk-1-enes and (E)-1-bromoalk-1-enes in good to high yields, respectively. Georg Thieme Verlag Stuttgart.
- Hoshi, Masayuki,Hayatsu, Takaki,Okimoto, Mitsuhiro,Kodama, Satoshi
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scheme or table
p. 2945 - 2948
(2010/02/28)
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- Palladium-catalyzed cross-coupling between vinyl halides and tert-butyl carbazate: First general synthesis of the unusual N-Boc-N-alkenylhydrazines
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(Chemical Equation Presented) N-Boc-N-alkenylhydrazines, an almost unknown type of compounds, have been prepared with high to moderate yields via palladium-catalyzed cross-coupling between alkenyl halides and fert-butyl carbazate. The present methodology represents the first general way to access this highly functionalized and unusual type of hydrazines.
- Barluenga, Jose,Moriel, Patricia,Aznar, Fernando,Valdes, Carlos
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p. 275 - 278
(2007/10/03)
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- One-pot synthesis of substituted styrenes from vicinal dibromoalkanes and arylboronic acids
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Dehydrobromination of vicinal dibromoalkanes in systems comprising 1,2-dimethoxy-ethane, N-butyl-N′-methylimidazolium tetrafluoroborate (or tetrabutylammonium bromide), and a base with subsequent palladium-catalyzed cross-coupling of the thus formed bromoalkenes with arylboronic acids furnished substituted styrenes. Springer Science+Business Media, Inc. 2007.
- Tikhonov,Vasil'ev,Chirskaya,Struchkova,Merkulova,Zlotin
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p. 122 - 129
(2008/02/08)
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- Reactions of ethyl bromodifluoroacetate in the presence of copper powder
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We have examined the reaction of ethyl bromodifluoroacetate (1) in the presence of copper powder as a procedure for the synthesis of compounds containing a CF2 group. The complex formed in the above reaction reacted with vinyl or aryl iodides t
- Sato,Omote,Ando,Kumadaki
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p. 509 - 515
(2007/10/03)
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- Synthesis of alkenyl- and aryldifluoroacetate using a copper complex from ethyl bromodifluoroacetate
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Ethyl bromodifluoroacetate reacted with alkenyl or aryl iodides in the presence of copper powder in dimethyl sulfoxide (DMSO) to give the corresponding alkenyl- or aryldifluoroacetates in moderate to good yields.
- Sato, Kazuyuki,Kawata, Ryuichi,Ama, Fumitaka,Omote, Masaaki,Ando, Akira,Kumadaki, Itsumaro
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p. 1013 - 1016
(2007/10/03)
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- Simple Stereospecific Syntheses of (E)-1-Chloro(or Bromo)alk-1-enes from Alk-1-ynes via Hydroboration
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Stereochemically pure (E)-1-chloro(or bromo)alk-1-enes were obtained in sufficiently good yields from alk-1-ynes via hydroboration with dialkylborane followed by reactions with facile reagents; corresponding copper(II) halides, in the presence of a small
- Masuda, Yuzuru,Hoshi, Masayuki,Arase, Akira
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p. 2723 - 2726
(2007/10/02)
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- Vinylic Organoboranes. 13. A Convenient Stereospecific Synthesis of (Z)-1-Halo-1-alkenes from 1-Alkynes via (E)-1-Alkenylborane Derivatives with Halogens
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The reaction of (E)-1-alkenylborane derivatives with bromine under various conditions was investigated, and a simple stereospecific synthesis of (Z)-1-bromo-1-alkenes has been developed.Addition of bromine to (E)-1-alkenyldisiamylborane, derived from the
- Brown, Herbert C.,Subrahmanyam, Chitti,Hamaoka, Tsutomu,Ravindran, Nair,Bowman, Donald H.,et al.
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p. 6068 - 6075
(2007/10/02)
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- A convenient preparation of mono- or gem-di-halogenoalkanes from α-sulfonyl carbanions and halogenolithiocarbenoids.
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Various α-sulfonyl carbanions have been shown to react at low temperature with di- or tri-halogenolithiocarbenoids, to give 1-mono- or 1,1-di-halogenoalkanes.Bromocarbenoids gave better results than their chloro-analogues.Reaction of dibromolithiomethane with α-lithiated sulfones gives a high yield of vinylic bromides, the stereochemistry of which is cleanly E.Evidence is presented that the carbenoid itself is responsible for the reaction, and is not first converted into the corresponding carbene.
- Charreau, Philippe,Julia, Marc,Verpeaux, Jean-Noel
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p. 201 - 210
(2007/10/02)
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- AN EFFICIENT METHOD FOR PREPARATION OF TRIMETHYLSILYL ETHYLENE OXIDE AND SOME OTHER TRIMETHYLSILYL OXIRANES
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Trimethylsilyl ethylene oxide and other α,β-epoxysilanes were obtained from corresponding (trimethylsilyl)alkenes by an one-pot procedure involving successive treatment with N-bromosuccinimide and aqueous sodium hydroxide.
- Jankowski, P.,Masnyk, M.,Wicha, J.
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p. 873 - 880
(2007/10/02)
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- SYNTHESIS OF ISOCOUMARINS VIA THALLATION-OLEFINATION OF BENZOIC ACIDS
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Benzoic acid and substituted benzoic acids are readily thallated by thallium(III) trifluoroacetate and subsequently reacted with palladium chloride and simple olefins, allylic halides, vinyl halides, or vinyl esters to give isocoumarins.The organic halide reactions are catalytic in palladium. 1,2- and 1,3-dienes also react catalytically to afford 4-alkylidene- and 3-vinyl-3,4-dihydroisocoumarins, respectively.Vinylcyclopropanes also afford 3-vinyl-3,4-dihydroisocoumarins.This highly convenient thallation-olefination approach appears quite general for the synthesis of isocoumarins.
- Larock, R. C.,Varaprath, S.,Lau, H. H.,Fellows, C. A.
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p. 5274 - 5284
(2007/10/02)
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- Application of Phase Transfer Catalysis, 14.- Preparation of Alkynes from Halides with Solid Potassium tert-Butoxide and Crown Ether
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Preparatively very simple and mild HX eliminations with solid potassium tert-butoxide in petroleum ether in the presence of catalytic amounts of crown-6 are described. 1,2-Dihalides (from alkenes) and 1,1-dihalides (from aldehydes) yield 1-alkynes; internal geminal dihalides (from symmetric ketones) give internal alkynes in excellent yields. 2,2-Dihalides (from methyl ketones) yield homogeneous 1-alkynes only if the 3-position is blocked. (E)-Haloalkenes lead also to alkynes in a syn-elimination process.
- Dehmlow, Eckehard V.,Lissel, Manfred
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