- Regioselective Hydroalkylation of Vinylarenes by Cooperative Cu and Ni Catalysis
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Disclosed here is a dual copper and nickel catalytic system with a silyl hydride source for promoting the linear selective hydroalkylation of vinylarenes. This carbon–carbon bond-forming protocol is applied to couple a variety of functionalized vinylarenes with alkyl halides applying a nickel(II) NNN pincer complex in the presence of an NHC-ligated copper catalyst. This combination allows for a 1 mol % loading of the nickel catalyst leading to turnover numbers of up to 72. Over 40 examples are presented, including applications for pharmaceutical diversification. Labeling experiments demonstrated the regioselectivity of the reaction and revealed that the copper catalyst plays a crucial role in enhancing the rate for formation of the reactive linear alkyl nickel complex. Overall, the presented work provides a complimentary approach for hydroalkylation reactions, whilst providing a preliminary mechanistic understanding of the cooperativity between the copper and nickel complexes.
- Ravn, Anne K.,Johansen, Martin B.,Skrydstrup, Troels
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supporting information
(2021/12/14)
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- Electroreductive Carbofunctionalization of Alkenes with Alkyl Bromides via a Radical-Polar Crossover Mechanism
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Electrochemistry grants direct access to reactive intermediates (radicals and ions) in a controlled fashion toward selective organic transformations. This feature has been demonstrated in a variety of alkene functionalization reactions, most of which proceed via an anodic oxidation pathway. In this report, we further expand the scope of electrochemistry to the reductive functionalization of alkenes. In particular, the strategic choice of reagents and reaction conditions enabled a radical-polar crossover pathway wherein two distinct electrophiles can be added across an alkene in a highly chemo- and regioselective fashion. Specifically, we used this strategy in the intermolecular carboformylation, anti-Markovnikov hydroalkylation, and carbocarboxylation of alkenes - reactions with rare precedents in the literature - by means of the electroreductive generation of alkyl radical and carbanion intermediates. These reactions employ readily available starting materials (alkyl halides, alkenes, etc.) and simple, transition-metal-free conditions and display broad substrate scope and good tolerance of functional groups. A uniform protocol can be used to achieve all three transformations by simply altering the reaction medium. This development provides a new avenue for constructing Csp3-Csp3 bonds.
- Zhang, Wen,Lin, Song
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supporting information
p. 20661 - 20670
(2020/12/23)
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- 1,2-Dibromotetrachloroethane: An efficient reagent for many transformations by modified Appel reaction
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An efficient and facile method has been developed for the synthesis of alkyl bromides from various alcohols under mild conditions using a triphenylphosphine (PPh 3) /1,2-dibromotetrachloroethane (DBTCE) complex in excellent yields and very short time (5 min). This method can also be applied for the transformation of chiral alcohols to their corresponding bromides in very high enantiomeric excess. The PPh 3 /DBTCE complex is also successfully applied to ring-opening reactions of cyclic ethers in mild conditions. Esterification, amidation, and formation of acid anhydrides under very mild experimental conditions are also successfully accomplished by following a modification of the Appel reaction protocol in this work.
- Essiz, Sel?uk,Da?tan, Arif
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p. 150 - 156
(2019/05/16)
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- Sulfonyl halide synthesis by thiol oxyhalogenation using NBS/NCS – iPrOH
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A rapid and facile method provides a general route to sulfonyl bromides/chlorides by the oxidation of thiols using NXS – ROH (X?=?Br,Cl, R?=?iPr) as an oxyhalogenation reagent. Control experiments suggest that the alcohol component is the source of oxygen. The proposed method enable the access to structurally diverse sulfonyl bromides and chlorides including challenging examples, inaccessible by other synthetic methods.
- Silva-Cuevas, Carolina,Perez-Arrieta, Carlos,Polindara-García, Luis A.,Lujan-Montelongo, J. Armando
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p. 2244 - 2247
(2017/05/16)
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- Halogenation of primary alcohols using a tetraethylammonium halide/[Et 2NSF2]BF4 combination
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The halogenation of primary alcohols is presented. The use of a combination of tetraethylammonium halide and [Et2NSF2]BF4 (XtalFluor-E) allows for chlorination and bromination reactions to proceed efficiently (up to 92% yield) with a wide range of alcohols. Iodination reactions are also possible albeit in lower yields.
- Pouliot, Marie-France,Mahe, Olivier,Hamel, Jean-Denys,Desroches, Justine,Paquin, Jean-Francois
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supporting information
p. 5428 - 5431,4
(2020/10/15)
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- Conversion of alcohols to bromides using a fluorous phosphine
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Reaction of alcohols with the fluorous phosphine-carbon tetrabromide complex in toluene or in a two-phase toluene-FC-72 system afforded the corresponding bromides in good yields. The fluorous-phosphine oxide is readily separated by liquid-liquid extraction, providing an alternative to the homogeneous triphenylphosphine-carbon tetrachloride conversion, as well as to the polymer-supported phosphine method. The fluorous phosphine oxide could be reduced and the product reused.
- Desmaris, Laurence,Percina, Nathalie,Cottier, Louis,Sinou, Denis
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p. 7589 - 7591
(2007/10/03)
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- Enantioselective preparation and enzymatic cleavage of spiroisoxazoline amides
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Several enantiopure spiroisoxazoline amides were prepared from tert- butylester 22, which is obtained via an enantiotopic groups differentiating high pressure Diels-Alder cycloaddition. Treatment of these amides with an isoxazoline-splitting enzyme, which
- Goldenstein, Kim,Fendert, Thomas,Proksch, Peter,Winterfeldt, Ekkehard
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p. 4173 - 4185
(2007/10/03)
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- Introduction of bromine and chlorine substituents in medium ring ethers and lactones
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A convenient preparation of α-halo enamines using oxalyl halides is described together with applications of these reagents in the halogenation of β-hydroxy cyclic ethers and lactones.
- Bendall, Justin G.,Payne, Andrew N.,Screen, Thomas E. O.,Holmes, Andrew B.
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p. 1067 - 1068
(2007/10/03)
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- One-step conversion of protected alcohols into alkyl halides using dimethylphosgeniminium salt
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Efficient conversion of tetrahydro-2-pyranyl (THP)protected alcohols into the corresponding halides using dichlorophosgeniminium chloride in the presence of tetraalkylammonium halide.
- Schlama,Gouverneur,Mioskowski
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p. 3517 - 3520
(2007/10/03)
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- Syntheses of Chiral Menthyl and Neomenthyl Sulfides, Sulfoxides and Sulfones
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Attempts to synthesize stereospecifically menthanethiol (2) and menthyl thiocyanate (3) from suitable electrophilic neomenthyl substrates (4a-c) and a variety of sulfur nucleophiles failed or predominatly led to β-elimination products.Almost quantitative
- Blanco, Jose Manuel,Caamano, Olga,Fernandez, Franco,Nieto, Isabel
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p. 538 - 541
(2007/10/03)
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- A facile conversion of tetrahydropyranyl ethers to the corresponding bromides and iodides
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Tetrahydropyranyl ethers are converted to the corresponding bromides and iodides upon reaction with NaI (or Libr) and BF3.Et2O (or ClSiMe3).
- Vankar, Yashwant D.,Shah, Kavita
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p. 1081 - 1084
(2007/10/02)
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- Stereochemistry of Nucleophilic Substitution of Menthyl Derivatives with Anion of Diphenylphosphine Oxide by an Action of Sodium Dihydridobis(2-methoxyethanolato)aluminate
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The reaction of an anion of diphenylphosphine oxide prepared by the action of sodium dihydridobis(2-methoxyethanolato)aluminate on the oxide with various menthyl or neomenthyl halides and sulfonates were studied to clarify the sterochemistry of the substi
- Yamashita, Mitsuji,Soeda, Yukio,Suzuki, Nobuyoshi,Yamada, Manabu,Tsunekawa, Kenji,et al.
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p. 1871 - 1872
(2007/10/02)
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