- Preparation of Primary and Secondary Dialkylmagnesiums by a Radical I/Mg-Exchange Reaction Using sBu2Mg in Toluene
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The treatment of primary or secondary alkyl iodides with sBu2Mg in toluene (25–40 °C, 2–4 h) provided dialkylmagnesiums that underwent various reactions with aldehydes, ketones, acid chlorides or allylic bromides. 3-Substituted secondary cyclohexyl iodides led to all-cis-3-cyclohexylmagnesium reagents under these exchange conditions in a highly stereoconvergent manner. Enantiomerically enriched 3-silyloxy-substituted secondary alkyl iodides gave after an exchange reaction with sBu2Mg stereodefined dialkylmagnesiums that after quenching with various electrophiles furnished various 1,3-stereodefined products including homo-aldol products (99 % dr and 98 % ee). Mechanistic studies confirmed a radical pathway for these new iodine/magnesium-exchange reactions.
- Knochel, Paul,Lutter, Ferdinand H.,Sunagatullina, Alisa S.
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supporting information
(2022/02/16)
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- A New Protocol for Catalytic Reduction of Alkyl Chlorides Using an Iridium/Bis(benzimidazol-2′-yl)pyridine Catalyst and Triethylsilane
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The reduction of alkyl chlorides using triethylsilane is investigated. Primary, secondary, tertiary, and benzylic C-Cl bonds are effectively converted into C-H bonds using an [IrCl(cod)] 2/2,6-bis(benzimidazol-2′-yl)pyridine catalyst system. This catalyst system is quite simple since the tridentate N-ligand can be easily prepared in one step from commercially available reagents.
- Fukuyama, Takahide,Hamada, Yuki,Ryu, Ilhyong
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p. 3404 - 3408
(2021/07/14)
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- UVA- and Visible-Light-Mediated Generation of Carbon Radicals from Organochlorides Using Nonmetal Photocatalyst
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Carbon radicals are reactive species useful in various organic transformations. The C-X bond cleavage of organohalides by photoirradiation is a common method to generate carbon radicals in a controlled fashion. The use of organochloride substrates is still a formidable challenge due to the low reduction potential and the high dissociation energy of the C-Cl bond. In this report, we address these issues by using a nonmetal organic molecule with a relatively simple structure as a photocatalyst. In this catalyst (bis(dimethylamino)carbazole), the amino groups increase both the HOMO and LUMO energy levels, especially in the former. As a result, compared to the parent molecule, the new catalyst shows experimentally red-shifted absorption in the visible region and forms an excited state with better reducing capability. This photocatalyst was used in the reduction of unactivated aryl chlorides and alkyl chlorides in the presence of hydrogen atom donor at room temperature. The catalytic system can also be applied to the coupling of aryl chlorides with electron-rich arene and heteroarenes to affect the C-C bond-forming reactions. Our mechanistic study results support the assumption that carbon radicals are formed from the organochlorides via a single-electron-transfer step.
- Matsubara, Ryosuke,Yabuta, Tatsushi,Md Idros, Ubaidah,Hayashi, Masahiko,Ema, Fumitoshi,Kobori, Yasuhiro,Sakata, Ken
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p. 9381 - 9390
(2018/07/25)
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- One-step Pd/C and Eu(OTf)3 catalyzed hydrodeoxygenation of branched C11 and C12 biomass-based furans to the corresponding alkanes
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Solvent-free NaOH catalyzed aldol condensation of biomass-derived 5-hydroxymethyl furfural (HMF) and furfural with methyl isobutyl ketone (MIBK) was studied, producing branched C11and C12furan compounds in high yields of up to 96%. Through use of a Pd/C and Eu(OTf)3catalytic system, the condensation products of the bio-based starting materials were further hydrodeoxygenated (HDO) in one-step to biofuel compatible branched alkanes 2-methylundecane (3) and 2-methyldecane (4) in excellent yields of 90% and 98%, respectively. In the one-step HDO developed herein, the variation of solvent had a significant effect on the reaction route and degree of conversion of furans to alkanes in the HDO process. Very high overall yields of alkanes 3 (86%) and 4 (94%) were obtained starting from the biomass-based HMF and furfural.
- Keskiv?li, Juha,Wrigstedt, Pauli,Lagerblom, Kalle,Repo, Timo
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- Photoinduced Charge-Transfer State of 4-Carbazolyl-3-(trifluoromethyl)benzoic Acid: Photophysical Property and Application to Reduction of Carbon?Halogen Bonds as a Sensitizer
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The photoinduced persistent intramolecular charge-transfer state of 4-carbazolyl-3-(trifluoromethyl)benzoic acid was confirmed. It showed a higher catalytic activity in terms of yield and selectivity in the photochemical reduction of alkyl halides compared to the parent carbazole. Even unactivated primary alkyl bromides could be reduced by this photocatalyst. The high catalytic activity is rationalized by considering the slower backward single-electron transfer owing to the spatial separation of the donor and acceptor subunits.
- Matsubara, Ryosuke,Shimada, Toshiyuki,Kobori, Yasuhiro,Yabuta, Tatsushi,Osakai, Toshiyuki,Hayashi, Masahiko
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supporting information
p. 2006 - 2010
(2016/07/28)
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- Fischer–Tropsch synthesis with cobalt catalyst and zeolite multibed arrangement
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The role of zeolite in transformations of hydrocarbons produced from CO and H2 over a Fischer–Tropsch cobalt catalyst under the conditions of multibed arrangement of the cobalt catalyst and the zeolite has been determined. Hydrocarbon conversion over the HBeta zeolite occurs via the bimolecular mechanism, as evidenced by a low methane yield and a high yield of unsaturated gaseous and liquid hydrocarbons. The conversion over the CaA zeolite obeys the unimolecular mechanism, as evidenced by the formation of increased amounts of methane and saturated gaseous C2–C4 hydrocarbons.
- Asalieva, E. Yu.,Kul’chakovskaya,Sineva,Mordkovich,Bulychev
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p. 275 - 280
(2016/06/09)
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- Simple, chemoselective, catalytic olefin isomerization
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Catalytic amounts of Co(SaltBu,tBu)Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.
- Crossley, Steven W. M.,Barabé, Francis,Shenvi, Ryan A.
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supporting information
p. 16788 - 16791
(2015/01/09)
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- Solvent-free synthesis of C10 and C11 branched alkanes from furfural and methyl isobutyl ketone
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Our best results jet: C10 and C11 branched alkanes, with low freezing points, are synthesized through the aldol condensation of furfural and methyl isobutyl ketone from lignocellulose, which is then followed by hydrodeoxygenation. These jet-fuel-range alkanes are obtained in high overall yields (≈90 %) under solvent-free conditions. Copyright
- Yang, Jinfan,Li, Ning,Li, Guangyi,Wang, Wentao,Wang, Aiqin,Wang, Xiaodong,Cong, Yu,Zhang, Tao
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p. 1149 - 1152
(2013/07/26)
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- A catalytic application of Co/Zr heterobimetallic complexes: Kumada coupling of unactivated alkyl halides with alkyl grignard reagents
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Tris(phosphanylamide) early/late heterobimetallic Zr/Co complexes, ClZr(R′NPR2)3CoI [R′ = iPr, R = Ph (1), R′ = 2,4,6-trimethylphenyl, R = iPr (2), R′ = R = iPr (3)], have been utilized as catalysts for the cross-coupling of alkyl halides with n-octylmagnesium bromide. While yields are consistently higher for alkyl bromide substrates, it is found that these unusual heterobimetallic complexes are also active towards more challenging alkyl chloride substrates. This is particularly interesting in light of the fact that monometallic cobalt complexes are inert towards these substrates, suggesting that Zr also plays a role in catalysis. Radical trapping studies suggest that a one-electron transfer radical oxidative addition pathway is operative.
- Zhou, Wen,Napoline, Jonathan Wesley,Thomas, Christine M.
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scheme or table
p. 2029 - 2033
(2011/06/25)
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- A structure-activity study of Ni-catalyzed alkyl-alkyl kumada coupling. Improved catalysts for coupling of secondary alkyl halides
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A structureactivity study was carried out for Ni catalyzed alkylalkyl Kumada-type cross coupling reactions. A series of new nickel(II) complexes including those with tridentate pincer bis(amino)amide ligands (RN2N) and those with bidentate mixed amino-amide ligands (RNN) were synthesized and structurally characterized. The coordination geometries of these complexes range from square planar, tetrahedral, to square pyramidal. The complexes had been examined as precatalysts for cross coupling of nonactivated alkyl halides, particularly secondary alkyl iodides, with alkyl Grignard reagents. Comparison was made to the results obtained with the previously reported Ni pincer complex [( MeN2N)NiCl]. A transmetalation site in the precatalysts is necessary for the catalysis. The coordination geometries and spin-states of the precatalysts have a small or no influence. The work led to the discovery of several well-defined Ni catalysts that are significantly more active and efficient than the pincer complex [(MeN2N)NiCl] for the coupling of secondary alkyl halides. The best two catalysts are [(HNN)Ni(PPh3)Cl] and [(HNN)Ni(2,4-lutidine)Cl]. The improved activity and efficiency was attributed to the fact that phosphine and lutidine ligands in these complexes can dissociate from the Ni center during catalysis. The activation of alkyl halides was shown to proceed via a radical mechanism.
- Ren, Peng,Vechorkin, Oleg,Von Allmen, Kim,Scopelliti, Rosario,Hu, Xile
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supporting information; experimental part
p. 7084 - 7095
(2011/06/26)
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- Cobalt-catalyzed cross-coupling reaction between functionalized primary and secondary alkyl halides and aliphatic Grignard reagents
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The coupling of primary and secondary unactivated alkyl bromides with alkyl-Grignard reagents was performed in good yields under mild conditions by using a new catalytic system: consisting of cobalt chloride and tetramethylethylenediamine (CoCl2·2 LiI, 4TMEDA). The reaction is very chemoselective since ketone, ester and nitrile functions are tolerated.
- Cahiez, Gerard,Chaboche, Christophe,Duplais, Christophe,Giulliani, Arianna,Moyeux, Alban
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supporting information; experimental part
p. 1484 - 1488
(2009/07/01)
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- Zirconocene-catalyzed alkylative dimerization of 2-methylene-1,3-dithiane via a single electron transfer process to provide symmetrical vic-bis(dithiane)s
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A mixture of tertiary alkyl halide and 2-methylene-1,3-dithiane was treated with butylmagnesium bromide in the presence of a catalytic amount of zirconocene dichloride. The reaction resulted in alkylative dimerization to yield the corresponding vic-bis(dithiane). The reaction would proceed as follows. A single electron transfer from low-valent zirconocene to alkyl halide would generate the corresponding alkyl radical. The radical adds to 2-methylene-1,3-dithiane to afford the corresponding radical stabilized by the two sulfur atoms. A couple of the stable radicals finally undergo dimerization.
- Yoshida, Suguru,Yorimitsu, Hideki,Oshima, Koichiro
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p. 3110 - 3114
(2008/02/08)
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- Alkylation of alkenes: Ethylaluminum sesquichloride-mediated hydro-alkyl additions with alkyl chloroformates and di-tert-butylpyrocarbonate
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A general method for the hydro-alkyl addition to the nonactivated C=C double bond of alkenes using alkyl chloroformates (primary, secondary), 12, and di-tert-butylpyrocarbonate, 52, mediated by ethylaluminum sesquichloride (Et3Al2Cl3) has been developed. Reaction of 12 and 52, respectively, with Et3Al2Cl3 gives an alkyl cation which is added to the alkene; hydride transfer to the adduct carbenium ion or, if applicable, 1,2-H shift followed by hydride transfer from Et3Al2Cl3 to the rearranged adduct carbenium ion gives the saturated addition product. The reaction has been applied to 1-alkenes, 2-methyl-1-alkenes, internal double bonds, and to three cyclic alkenes. Special interest has been focused on alkylations of unsaturated fatty compounds, such as oleic acid (2), which are important renewable feedstocks. 2-Methylalkanes, 3-methylalkanes, 2,4-dimethylalkanes, 2,3-dimethylalkanes, 2,2,4-trimethylalkanes, cyclohexylalkanes, and carboxylic acids and esters with the respective branched alkyl chain have been synthesized with good to moderate yields.
- Biermann, Ursula,Metzger, Juergen O.
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p. 10319 - 10330
(2007/10/03)
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- Nickel-catalyzed cross-coupling reaction of Grignard reagents with alkyl halides and tosylates: Remarkable effect of 1,3-butadienes
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A new method for the cross-coupling reaction of Grignard reagents with alkyl chlorides, bromides, and tosylates has been developed by the use of a nickel catalyst in the presence of a diene as an additive. This reaction proceeds efficiently at 0-25 °C in THF using primary and secondary alkyl and aryl Grignard reagents. Nickel complexes bearing no phosphine ligands, such as NiCl2, Ni(acac)2, and Ni(COD)2, afford the coupling products in good yields, whereas NiCl2(PPh3)2 and NiCl2(dppp) were less effective. 1,3-Butadiene shows the highest activity as an additive for the present coupling reaction. A plausible reaction pathway was proposed. Copyright
- Terao, Jun,Watanabe, Hideyuki,Ikumi, Aki,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 4222 - 4223
(2007/10/03)
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- Cu-catalyzed alkylation of Grignard reagents: A new efficient procedure
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The presence of NMP (4-9 equiv.) clearly improves the yield and the chemoselectivity of the Cu-catalyzed alkylation of organomagnesium reagents. Thus, secondary and tertiary alkylmagnesium chlorides were used successfully for the first time in such a reaction and ester, amide, nitrile or keto groups are tolerated. The procedure is cheap, environmentally friendly and very easy to carry out (1-3% Li2CuCl4 or CuCl, THF, 20°C). It is an interesting alternative to the classical alkylation of organocuprates reagents. (C) 2000 Published by Elsevier Science Ltd.
- Cahiez, Gérard,Chaboche, Christophe,Jézéquel, Michelle
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p. 2733 - 2737
(2007/10/03)
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- Friedel-Crafts alkylation of alkenes: Ethylaluminum sesquichloride induced alkylations with alkyl chloroformates
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The formal addition of propane to nonactivated double bonds can be achieved with isopropyl chloroformate (2) in the presence of Et3Al2Cl3. Thus, a 1:1 mixture of 10-isopropyloctadecanoic acid (3) and the 9- regioisomer is formed from oleic acid (1). The reaction may also be carried out with 1-alkenes by the addition of triethylsilane as a hydride donor.
- Biermann, Ursula,Metzger, Juergen O.
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p. 3675 - 3677
(2007/10/03)
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- Novel tridentate diamino organomanganese(II) complexes as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon-carbon bond forming reactions
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The new, paramagnetic arylmanganese(II) complex Li[MnCl2(NCN)] (2, NCN [C6H3(CH2NMe2)2-2,6] -) has been obtained in high yield from the reaction of MnCl2 and [Li(NCN)]2 in a 2:1 molar ratio. In THF solution, 2 is likely an ionic species [Li(THF)n] [MnCl2(NCN)] (molecular weight determination and conductivity measurements), while magnetic measurements indicate that a high spin d5 manganese(II) center is present. Subsequent reaction of 2 with RLi afforded [MnR(NCN)] (R=Me (3a), n-Bu (3b)). Complex 2, using CuCl as a co-catalyst, is an effective catalyst system for cross-coupling of Grignard reagents with alkyl bromides and the 1,4-addition of organomagnesium halides to α,β-unsaturated ketones. No further additives or co-solvents are necessary. For both reactions a dramatic decrease in reaction times is observed when compared to standard manganese/copper systems. Alkyl bromides with unsaturated or heteroatom functionalities can be cross-coupled. Also, excellent reactivity towards normally unreactive β,β-disubstituted ketones has been observed in the 1,4-addition reaction.
- Donkervoort, Johannes G.,Vicario, Jose L.,Jastrzebski, Johann T.B.H.,Gossage, Robert A.,Cahiez, Gerard,Van Koten, Gerard
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- Novel organomanganese(II) complexes active as homogeneous catalysts in manganese(II)/copper(I) catalyzed carbon-carbon bond formation reactions
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Novel organomanganese complexes 3 and 4 were prepared via transmetallation of the corresponding organolithium reagent. These new complexes are active catalysts in manganese/copper mediated cross-coupling reactions.
- Donkervoort, Johannes G.,Vicario, Jose L.,Jastrzebski, Johann T.B.H.,Cahiez, Gerard,Van Koten, Gerard
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p. 547 - 548
(2007/10/03)
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- Catalytic oxidation-reduction hydration of olefin with molecular oxygen in the presence of bis(1,3-diketonato)cobalt(II) complexes
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In the presence of a bis(1,3-diketonato)cobalt(II) complex, various olefins are converted to the corresponding hydrated products according to the Markownikov rule on treatment with molecular oxygen in secondary alcohol (''oxidation-reduction hydration''). Removal of water formed during the hydration reaction, especially by azeotropic method, is remarkably effective to improve yields of the hydrated products based on the cobalt(II) catalyst as bis(trifluoroacetylacetonato)cobalt(II) (Co(tfa)2) or bis(2-ethoxycarbonyl-3-oxobutanalato)-cobalt(II) (Co(ecbo)2).
- Kato,Yamada,Takai,Inoki,Isayama
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p. 179 - 186
(2007/10/02)
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- Identification of the Aggregation Pheromone of Flour Beetles Tribolium castaneum and T. confusum (Coleoptera: Tenebrionidae)
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The aggregation pheromone produced by the male red flour beetle Tribolium castaneum, and confused flour beetles, T. confusum was identified as 4,8-dimethyldecan-1-al by GLC, GC-MS, PMR spectra, and synthesis of the compound.The synthetic pheromone was less attractive compared with the natural pheromone, because the synthetic sample was composed of four optical isomers.
- Suzuki, Takahisa
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p. 1357 - 1364
(2007/10/02)
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