- Facile SN' Reaction of Alkyl-lithiums with 2-Vinyl-1,3-dioxane
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Treatment of 2-vinyl-1,3-dioxane with n-, s-, or t-butyl-lithium in diethyl ether or n-pentane solution results in facile nucleophilic addition of RLi to the carbon-carbon double bond with concomitant cleavage of the ring C-O bond (SN' process) to give high yields of enol ethers having the structure HO3OCH=CHCH2R.
- Bailey, William F.,Zartun, Donna L.
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- Copper-catalyzed alkyl-alkyl cross-coupling reactions using hydrocarbon additives: Efficiency of catalyst and roles of additives
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Cross-coupling of alkyl halides with alkyl Grignard reagents proceeds with extremely high TONs of up to 1230000 using a Cu/unsaturated hydrocarbon catalytic system. Alkyl fluorides, chlorides, bromides, and tosylates are all suitable electrophiles, and a TOF as high as 31200 h-1 was attained using an alkyl iodide. Side reactions of this catalytic system, i.e., reduction, dehydrohalogenation (elimination), and the homocoupling of alkyl halides, occur in the absence of additives. It appears that the reaction involves the β-hydrogen elimination of alkylcopper intermediates, giving rise to olefins and Cu-H species, and that this process triggers both side reactions and the degradation of the Cu catalyst. The formed Cu-H promotes the reduction of alkyl halides to give alkanes and Cu-X or the generation of Cu(0), probably by disproportionation, which can oxidatively add to alkyl halides to yield olefins and, in some cases, homocoupling products. Unsaturated hydrocarbon additives such as 1,3-butadiene and phenylpropyne play important roles in achieving highly efficient cross-coupling by suppressing β-hydrogen elimination, which inhibits both the degradation of the Cu catalyst and undesirable side reactions.
- Iwasaki, Takanori,Imanishi, Reiko,Shimizu, Ryohei,Kuniyasu, Hitoshi,Terao, Jun,Kambe, Nobuaki
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p. 8522 - 8532
(2015/01/08)
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- Copper nanoparticle-catalyzed cross-coupling of alkyl halides with Grignard reagents
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A cross-coupling reaction between alkyl bromides and chlorides and various Grignard reagents was carried out in the presence of commercially available copper or copper oxide nanoparticles as a catalyst and an alkyne additive. The catalytic system shows high activity, a broad scope, and good functional group tolerance.
- Kim, Ju Hyun,Chung, Young Keun
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supporting information
p. 11101 - 11103
(2013/11/19)
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- Fe-catalysed Kumada-type alkyl-alkyl cross-coupling. Evidence for the intermediacy of Fe(i) complexes
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A novel Fe-NHC catalytic system allows the alkyl-alkyl cross-coupling reaction of alkyl halides and alkylmagnesium reagents has been developed. To our knowledge, this is the first Fe-catalysed Kumada-type coupling for the formation of C(sp3)-C(sp3) bonds in the presence of functional groups. The process takes place under mild conditions, avoiding the formation of β-elimination products. Mechanistic studies suggest the intermediacy of Fe(i) complexes, formed by reduction with the Grignard reagent, as the active species.
- Guisan-Ceinos, Manuel,Tato, Francisco,Bunuel, Elena,Calle, Paloma,Cardenas, Diego J.
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p. 1098 - 1104
(2013/06/04)
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- Highly efficient and chemoselective acetalization of carbonyl compounds catalyzed by new and reusab e zirconyl triflate, zr0(0tf)2
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Various types of aromatic aldehydes were efficiently converted to their corresponding 1,3-dioxanes and 1,3-dioxolane with 1,3-propanediol and ethylene glycol, respectively, in the presence of catalytic amount of ZrO(OTf) 2 in acetonitrile at room temperature. The catalyst can be reused several times without loss of its catalytic activity. Very short reaction times, selective acetalization of aromatic aldehydes in the presence of aliphatic aldehydes and ketones, very mild reaction conditions, reusability of the catalyst, and easy workup are noteworthy advantages of this method.
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Yazdani, Parvin,Ghorjipoor, Saeedeh
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experimental part
p. 131 - 135
(2009/09/30)
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- Nickel-catalyzed cross-coupling of unactivated alkyl halides and tosylate carrying a functional group with alkyl and phenyl Grignard reagents
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By the use of catalytic amounts of a nickel salt and a 1,3-butadiene, primary and secondary alkyl Grignard reagents undergo cross-coupling with alkyl bromides, iodide, and tosylate carrying a functional group such as amide, ester, and ketone at 0 °C in THF. The present procedure provides a simple, convenient, and practical method for construction of carbon chains in the presence of various functional groups. PhMgBr also gave the corresponding coupling product in a moderate yield.
- Singh, Surya Prakash,Terao, Jun,Kambe, Nobuaki
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scheme or table
p. 5644 - 5646
(2011/02/25)
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- N-bromosuccinimide (NBS) catalyzed highly chemoselective acetalization of carbonyl compounds using silylated diols and pentaerythritol under neutral aprotic conditions
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Various types of carbonyl compounds are efficiently converted to their 1,3-dioxanes and pentaerythritol diacetals by the use of either 1,3-bistrimethylsiloxy propane (A) or 1,3-bistrimethylsilanyloxy-2,2- bistrimethylsilanyloxymethyl propane (D) and a catalytic amount of N-bromosuccinimide (3-10 mol%) under essentially neutral aprotic condition, respectively. A variety of functionalities such as both aliphatic and phenolic -OTBDMS, -OMe, -OBz, furan ring, double bonds and more significantly phenolic -OTHP survived under the present reaction condition. The efficient conversion of two α-tertiary ketones to their cyclic acetals was also achieved using the present protocol.
- Karimi, Babak,Hazarkhani, Hassan,Maleki, Jafar
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p. 279 - 285
(2007/10/03)
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- Acetals and Ethers. 11. Solubility of Alkyl-Substituted 1,3-Dioxolanes and 1,3-Dioxanes in Water
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2-Alkyl-1,3-dioxolanes, 2-alkyl-4-methyl-1,3-dioxolanes, and 2-alkyl-1,3-dioxanes (alkyl: n-C3H7, ...,n-C6H13) were synthesized and their solubilities in E10-4 M aqueous sodium bicarbonate solution at 293.2 K determined.The standard free energies for transfer from aqueous solution to pure liquid phase, ΔGto, were calculated from the solubility data and the contributions of given fragments of molecules to the free energy estimated.The fve-membered 1,3-dioxolane and six-membered 1,3-dioxane rings given fragments of molecules to the free energy contribution ΔGto, related to the cyclic fragments of the molecules, are +2.84 +/- 0.20 and +2.26 +/- 0.36 kJ mol-1, respectively.Their hydrophilicity is, however, much weaker than hat of the hydroxy group in normal alcohols.The 1,3-dioxolane ring bearing a methyl group at the C-4 atom has a markedly weaker hydrophilic character.
- Sokolowski, Adam,Burczyk, Bogdan,Oles, Jan
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p. 807 - 809
(2007/10/02)
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- SYNTHESIS OF DIMETHYL ACETALS, DIETHYL ACETALS, AND CYCLIC ACETALS CATALYZED BY AMINOPROPYLATED SILICA GEL HYDROCHLORIDE (APSG*HCl)
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The aminopropylated Silica-Gel hydrochloride (APSG*HCl) proved to be an efficient catalyst for the rapid conversion of carbonyl compounds in the corresponding acetals with high yields and in mild and selective conditions.In addition to the obvious advantages offered by heterogeneous catalysis, the present method results very useful when the presence of a weakly-acidic function chemically bonded on the catalyst surface (alkyl ammonium salt) is necessary (compounds which contains functions unstable in acidic media).
- Gasparrini, F.,Giovannoli, M.,Misiti, D.,Palmieri, G.
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p. 1491 - 1500
(2007/10/02)
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