- A new coupling reaction of alkyl iodides with α,β-unsaturated esters using Ni2B(cat.)-BER in methanol
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Alkyl iodides can be coupled with α,β-unsaturated esters using Ni2B(0.05-0.2 eq)-BER(3 eq) in methanol at room temperature. Products (68-95%) are conveniently isolated, simply filtering the resin and evaporating the excess enoates and methanol.
- Sim, Tae Bo,Choi, Jaesung,Yoon, Nung Min
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- An unprecedented and highly chemoselective esterification method
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A series of carboxylic acids was transformed to their corresponding methyl esters under CBr4/CH3OH (0.05 eq., 5 ml) reaction conditions. The rate of esterification is decreased with increasing bulkiness of the alcohol. Chemoselectivity can be achieved between phenylacetic and benzoic acids, sp3-C and sp2-C acids as well as between sp3-C and sp-C tethered carboxylic acids.
- Lee, Shih-Yuan Adam,Yang, Hui-Chun,Su, Feng-Yih
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- Cobalt-catalyzed reductive coupling of saturated alkyl halides with activated alkenes
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An efficient cobalt-catalyzed reductive coupling reaction of alkyl halides with electron-withdrawing alkenes (CH2=CR1EWG, EWG = electron-withdrawing group) in the presence of water and zinc powder in acetonitrile to give the corresponding Michael-type addition product (RCH 2CR1EWG) was described. The methodology is versatile such that unactivated primary, secondary, and tertiary alkyl bromides and iodides and various conjugated alkenes including acrylates, acrylonitrile, methyl vinyl ketone, and vinyl sulfone all successfully participate in this coupling reaction. For the alkyl halides used in the reaction, the iodides generally gave heller yields compared to those of the corresponding bromides. It is a unique method employing CoI2dppe, zinc, and alkyl halides, affording conjugate addition products in high yields. Mechanistically, the reaction appears to follow an oxidative addition driven route rather than the previously reported radical route.
- Shukla, Paritosh,Hsu, Yun-Chu,Cheng, Chien-Hong
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- Reductive bromine atom-transfer reaction
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Atom-transfer radical (ATR) reactions of alkenes with R-X usually give products having new C-C and C-X bonds at the adjacent carbons. However, when the reaction was carried out under irradiation using a low-pressure Hg lamp, addition/reduction products were obtained in good yield. Hydrogen bromide, formed by H-abstraction of a bromine radical from alkenes, is likely to play a key role in the reductive ATR reaction.
- Sumino, Shuhei,Fusano, Akira,Ryu, Ilhyong
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- REACTIONS OF ORGANIC HALIDES WITH OLEFINS UNDER Ni0-CATALYSIS. FORMAL ADDITION OF HYDROCARBONS TO CC-DOUBLE BONDS
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The reaction of various types of organic halides with electron deficient olefins under the influence of NiCl2 x 6 H2O in the presence of zinc and pyridine leads to formal addition products of hydrocarbons to CC-double bonds in good yield.
- Sustmann, Reiner,Hopp, Peter,Holl, Peter
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- BIS(TRI-n-BUTYLSTANNYL)BENZOPINACOLATE: PREPARATION AND USE AS A MEDIATOR OF INTERMOLECULAR FREE RADICAL REACTIONS
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Bis(tri-n-butylstannyl)benzopinacolinate (2) serves as a thermal source of tri-n-butylstannyl radicals and mediates intermolecular coupling of selected alkyl halides to O-benzylformaldoxime and electron deficient olefins.A free radical non-chain mechanism is proposed for these reactions.
- Hart, David J.,Krishnamurthy, Ramanarayanan,Pook, Lori M.,Seely, Franklin L.
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- Copper-Catalyzed Alkoxycarbonylation of Alkyl Iodides for the Synthesis of Aliphatic Esters: Hydrogen Makes the Difference
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A copper-catalyzed alkoxycarbonylation transformation of unactivated alkyl iodides has been developed. Various alkyl iodides can be converted into the corresponding tert-butyl esters in good yields. NaOtBu acts as both a nucleophile and a base. Moreover, other types of aliphatic esters can also be obtained in moderated yields if extra alcohols are added. Both primary and secondary alkyl alcohols can react successfully.
- Geng, Hui-Qing,Wu, Xiao-Feng
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p. 8062 - 8066
(2021/10/25)
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- Electrochemical Tandem Olefination and Hydrogenation Reaction with Ammonia
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An electrochemical Horner-Wadsworth-Emmons/hydrogenation tandem reaction was achieved using ammonia as electron and proton donors. The reaction could give two-carbon-elongated ester and nitrile from aldehyde or ketones directly. This reaction could proceed with a catalytic amount of base or even without a base. The ammonia provides both the electron and proton for this tandem reaction and enables the catalyst-free hydrogenation of an α,β-unsaturated HWE intermediate. More than 40 examples were reported, and functional groups, including heterocycles and hydroxyl, were tolerated.
- Zhang, Xiaofeng,Jiang, Runze,Cheng, Xu
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supporting information
p. 16016 - 16025
(2021/08/24)
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- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
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The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
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Paragraph 0094-0096; 0098; 0100-0104
(2021/05/29)
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- Copper catalyzed C(sp3)-H bond alkylation via photoinduced ligand-to-metal charge transfer
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Utilizing catalytic CuCl2 we report the functionalization of numerous feedstock chemicals via the coupling of unactivated C(sp3)-H bonds with electron-deficient olefins. The active cuprate catalyst undergoes Ligand-to-Metal Charge Transfer (LMCT) to enable the generation of a chlorine radical which acts as a powerful hydrogen atom transfer reagent capable of abstracting strong electron-rich C(sp3)-H bonds. Of note is that the chlorocuprate catalyst is an exceedingly mild oxidant (0.5 V vs SCE) and that a proposed protodemetalation mechanism offers a broad scope of electron-deficient olefins, offering high diastereoselectivity in the case of endocyclic alkenes. The coupling of chlorine radical generation with Cu reduction through LMCT enables the generation of a highly active HAT reagent in an operationally simple and atom economical protocol.
- Treacy, Sean M.,Rovis, Tomislav
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supporting information
p. 2729 - 2735
(2021/03/01)
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- Dual Benzophenone/Copper-Photocatalyzed Giese-Type Alkylation of C(sp3)?H Bonds
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Photocatalyzed Giese-type alkylations of C(sp3)?H bonds are very attractive reactions in the context of atom-economy in C?C bond formation. The main limitation of such reactions is that when using highly polymerizable olefin acceptors, such as unsubstituted acrylates, acrylonitrile, or methyl vinyl ketone, radical polymerization often becomes the dominant or exclusive reaction pathway. Herein, we report that the polymerization of such olefins is strongly limited or suppressed when combining the photocatalytic activity of benzophenone (BP) with a catalytic amount of Cu(OAc)2. Under mild and operationally simple conditions, the Giese adducts resulting from the C(sp3)?H functionalization of amines, alcohols, ethers, and cycloalkanes could be synthesized. Preliminary mechanistic studies have revealed that the reaction does not proceed through a radical chain, but through a dual BP/Cu photocatalytic process, in which both CuII and low-valent CuI/0 species, generated in situ by reduction by the BP ketyl radical, may react with α-keto or α-cyano intermediate radicals, thus preventing polymerization.
- Abadie, Baptiste,Jardel, Damien,Pozzi, Gianluca,Toullec, Patrick,Vincent, Jean-Marc
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supporting information
p. 16120 - 16127
(2019/11/26)
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- Copper(i)-catalysed transfer hydrogenations with ammonia borane
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Highly Z-selective alkyne transfer semihydrogenations and conjugate transfer hydrogenations of enoates can be effected by employing a readily available and air-stable copper(i)/N-heterocyclic carbene (NHC) complex, [IPrCuOH]. As an easy to handle and potentially recyclable H2 source, ammonia borane (H3NBH3) is used.
- Korytiaková, Eva,Thiel, Niklas O.,Pape, Felix,Teichert, Johannes F.
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supporting information
p. 732 - 735
(2017/01/13)
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- Palladium-Catalyzed Asymmetric α-Arylation of Alkylnitriles
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Asymmetric arylation of alkylnitriles forms quaternary stereocenters in good enantiocontrol for the first time. A lithium heterodimer consisting of an alkylnitrile anion and a disilylamide ion is the actual species responsible for the stereodetermining transmetalation in the catalytic cycle.
- Jiao, Zhiwei,Chee, Kwok Wei,Zhou, Jianrong Steve
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p. 16240 - 16243
(2016/12/27)
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- Hydroalkylation of Alkenes Using Alkyl Iodides and Hantzsch Ester under Palladium/Light System
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The hydroalkylation of alkenes using alkyl iodides with Hantzsch ester as a hydrogen source occurred smoothly under a Pd/light system, in a novel, tin-free Giese reaction. A chemoselective reaction at C(sp3)-I in the presence of a C(sp2)-X (X = Br or I) bond was attained, which allowed for the stepwise functionalization of two types of C-X bonds in a one-pot procedure.
- Sumino, Shuhei,Ryu, Ilhyong
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supporting information
p. 52 - 55
(2016/01/12)
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- Transition metal nanoparticles stabilized by ammonium salts of hyperbranched polystyrene: effect of metals on catalysis of the biphasic hydrogenation of alkenes and arenes
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Abstract Hyperbranched polystyrene bearing ammonium salts (HPS-NR3+Cl-) behaves as an excellent stabilizer of ruthenium, rhodium, iridium, palladium, and platinum nanoparticles from 1 to 3 nm in size uniformly dispersed in the polymer matrix. The catalytic performance of the resulting metal-polymer composites, M@HPS-NR3+Cl-, is dependent on the metal. This dependence was investigated by assessing the hydrogenation of alkenes and arenes. The utility of M@HPS-NR3+Cl- as reusable catalysts in aqueous/organic biphasic systems was demonstrated by examining the catalysis of the hydrogenation of aromatic compounds containing various functional groups by Ru@HPS-NR3+Cl-.
- Gao, Lei,Kojima, Keisuke,Nagashima, Hideo
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p. 6414 - 6423
(2015/08/18)
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- Borohydride-mediated radical addition reactions of organic iodides to electron-deficient alkenes
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Cyanoborohydrides are efficient reagents in the reductive addition reactions of alkyl iodides and electron-deficient olefins. In contrast to using tin reagents, the reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine or carbon-chlorine bond. The reaction system was successfully applied to three-component reactions, including radical carbonylation. The rate constant for the hydrogen abstraction of a primary alkyl radical from tetrabutylammonium cyanoborohydride was estimated to be 4 M-1 s-1 at 25 °C by a kinetic competition method. This value is 3 orders of magnitude smaller than that of tributyltin hydride.
- Kawamoto, Takuji,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide,Matsubara, Hiroshi,Ryu, Ilhyong
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p. 3999 - 4007
(2014/05/20)
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- Tin-free giese reaction and the related radical carbonylation using Alkyl iodides and cyanoborohydrides
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Tin-free Giese reaction and the related radical carbonylation process proceeded efficiently in the presence of sodium cyanoborohydride and tetrabutylammonium cyanoborohydride. The reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine and carbon-chlorine bonds. The iodine atom transfer followed by hydride reduction of the resulting carbon-iodine bond is proposed as a possible mechanism.
- Ryu, Ilhyong,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide
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supporting information; experimental part
p. 1005 - 1008
(2009/04/07)
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- Nickel-catalyzed 1,4-addition of trialkylboranes to α,β- unsaturated esters: Dramatic enhancement by addition of methanol
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Equation presented Nickel catalyst systems for 1,4-addition of trialkylboranes to α,β-unsaturated esters have been developed. Addition of methanol was found to be essential for the alkylation reaction with 9-alkyl-9-BBNs.
- Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1541 - 1544
(2008/02/02)
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- Catalytic generation of activated carboxylates from enals: A product-determining role for the base
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(Chemical Equation Presented) N-Heterocycle carbenes generated in situ from imidazolium or triazolium salts and bases react with enals, leading to the catalytic generation of homoenolates. The fate of these intermediates is determined by the catalytic base: strong bases such as tBuOK lead to carbon-carbon bond formation, while weaker bases allow protonation of the homoenolate and subsequent generation of activated carboxylates. This discovery, along with the design of a new triazolium precatalyst, enables the catalytic, atom-economical redox esterification of enals.
- Sohn, Stephanie S.,Bode, Jeffrey W.
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p. 3873 - 3876
(2007/10/03)
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- A Simple and Efficient Esterification Method
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A convenient and practical esterification was realized and this reaction proceeded without a dehydrating reagent or water removal equipment. The synthesis of esters by reaction of carboxylic acids with various alcohols such as methyl, ethyl, isopropyl, isobutyl, allyl, benzyl, propargyl and decanyl alcohols were achieved with a catalytic amount of CBr4 under refluxing reaction condition.
- Ming-Yi, Chen,Lee, Adam Shih-Yuan
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p. 103 - 108
(2007/10/03)
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- Selective 1,4-reduction of α,β-unsaturated carbonyl compounds by combined use of bis(l,3-diketonato)cobait(II) complex and diisobutylaluminum hydride
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By the combined use of Co(acac)2 with DIBAL, various α,β-unsaturated carbonyl compounds such as enones, α,β-unsaturated carboxylates and carboxamides were selectively reduced in a 1,4-manner to obtain the corresponding 1,4-reduced products in good-to-high yields. Thieme.
- Ikeno, Taketo,Kimura, Tomomi,Ohtsuka, Yuhki,Yamada, Tohru
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- A New Coupling Reaction of Alkyl Iodides with Electron Deficient Alkenes Nickel Boride (cat.) - Borohydride Exchange Resin in Methanol
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The radical addition reaction of alkyl iodides with α,β-unsaturated esters, nitriles, and ketones proceeds in moderate to excellent yields (50-95%) using Ni(OAc)2 (0.05-0.2 equiv) - BER (3-5 equiv) in methanol in 1-9 h at room temperature or at 65°C. Nickel boride on borohydride exchange resin (BER) is a good alternative reagent to tributyltin hydride for the coupling of alkyl iodides with the electron deficient alkenes in methanol. Compared with tributyltin hydride method, this method has an advantage of simple workup, since nickel boride - BER can be removed readily by filtration.
- Sim, Tae Bo,Choi, Jaesung,Joung, Meyoung Ju,Yoon, Nung Min
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p. 2357 - 2361
(2007/10/03)
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- Homolytic Reactions of Ligated Boranes. Part 9. Overall Addition of Alkanes to Electron-deficient Alkenes by a Radical Chain Mechanism
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Methyl bromoacetate and ethyl 2-bromopropanoate are reduced by Bun3P->BH3 or Bun3P->BH2Ph to methyl acetate and ethyl propanoate, respectively, in chlorobenzene at 80-110 deg C in the presence of dibenzoyl peroxide or t-butyl perbenzoate.Amine complexes of borane or phenylborane are much less effective reducing agents.The reductions may also be initiated photochemically and are inhibited by a phenolic radical scavenger.A homolytic chain mechanism is proposed in which the phosphine-boryl radical abstracts halogen from the bromo ester and is subsequently regenerated by reaction of an α-(alkoxycarbonyl)alkyl radical with the phosphine-borane.The latter propagation step, together with halogen abstraction from RI and addition of the derived alkyl radical to the C=C bond, is also involved in the chain reaction between Bun3P->BH2Ph, an alkyl iodide, and ethyl acrylate according to equation (A); Bun3P->BH3 reacts similarly but gives lower yields of ester.Reaction (A) proceeds smoothly at 110 deg C Bun3P->BH2Ph + RI + CH2=CHCO2Et -> RCH2CH2CO2Et + Bun3P->BHIPh (A) when initiated by t-butyl perbenzoate and moderate yields of isolated esters were obtained from n-butyl iodide, cyclohexyl iodide, and 3β-iodocholest-5-ene.This last iodide gives an epimeric mixture of 3α- and 3β-esters in total isolated yield of ca. 50 percent.Similar addition reactions take place between Bun3P->BH2Ph, BunI, and diethyl vinylphosphonate or phenyl vinyl sulphone.It is concluded that Bun3P->BH3 and particularly Bun3P->BH2Ph offer promise as alternatives to tin, mercury, and germanium hydrides in radical chain reactions of synthetic value.
- Baban, Jehan A.,Roberts, Brian P.
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p. 1195 - 1200
(2007/10/02)
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- New Synthetic Methods. Conjugate Addition of Alkyl Groups to Electron Deficient Olefins with Nitroalkanes as Alkyl Anion Equivalents
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The sequence of the Michael addition of nitroalkanes and denitration from the adduct provides a new and general method for conjugate addition of primary and secondary alkyl groups to electron deficient olefins such as α,β-unsaturated aldehydes, ketones, esters, nitriles, sulfoxides, and sulfones.
- Ono, Noboru,Kamimura, Akio,Miyake, Hideyoshi,Hamamoto, Isami,Kaji, Aritsune
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p. 3692 - 3698
(2007/10/02)
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