- Utilization of tetrabutylammonium triphenyldifluorosilicate as a fluoride source for silicon-carbon bond cleavage
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Tetrabutylammonium triphenyldifluorosilicate (TBAT) can be employed as a fluoride source to cleave silicon-carbon bonds thus generating in situ carbanions that coupled with a variety of electrophiles, including aldehydes and ketones, in moderate to high yields. Among the examples reported is the first instance of fluoride-induced intermolecular coupling between allyltrimethylsilane and imine derivatives. Also, of particular note is the TBAT-initiated coupling of primary alkyl halides with allyltrimethylsilane. TBAT is an easily handled crystalline solid that has several advantages over tetrabutylammonium fluoride (TBAF) as a fluoride source; it is anhydrous, nonhygroscopic, soluble in most commonly used organic solvents, and less basic than TBAF.
- Pilcher, Anthony S.,DeShong, Philip
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- Iron-catalyzed AlkylAlkyl negishi coupling of organoaluminum reagents
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The first iron-catalyzed cross-coupling reaction of alkyl halides with alkylaluminum reagents (alkylalkyl Negishi coupling) is developed using an iron/bisphosphine catalyst system. The reaction shows high functional group tolerance: various primary alkyl halides possessing a non-protected indole, carboxyl, or hydroxy group are coupled with primary alkylaluminum reagents in good yields. Potassium fluoride plays a key role to promote the reaction by generating an aluminate species, which facilitates the transmetalation between the organoaluminum and the iron catalyst.
- Agata, Ryosuke,Kawamura, Shintaro,Isozaki, Katsuhiro,Nakamura, Masaharu
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supporting information
p. 238 - 241
(2019/03/13)
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- Nickel-catalyzed cross-coupling of umpolung carbonyls and alkyl halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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- Nickel-Catalyzed Cross-Coupling of Umpolung Carbonyls and Alkyl Halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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p. 6312 - 6322
(2019/05/24)
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- Stabilization of long-chain intermediates in solution. octyl radicals and cations
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The rearrangements of 1-octyl, 1-decyl and 1-tridecyl intermediates obtained from thermal lead(IV) acetate (LTA) decarboxylation of nonanoic, undecanoic and tetradecanoic acid were investigated experimentally through analysis and distribution of the products. The relationships between 1,5-, 1,6- and possibly existing 1,7-homolytic hydrogen transfer in 1-octyl-radical, as well as successive 1,2-hydride shift in corresponding cation have been computed via Monte-Carlo method. Taking into account that ratios of 1,5-/1,6-homolytic rearrangements in 1-octyl- and 1-tridecyl radical are approximately the same, the simulation shows very low involvement of 1,7-hydrogen rearrangement (1,5-/1,6-/1,7-hydrogen rearrangement = 85:31:1) in 1-octyl radical.
- Teodorovi?, Aleksandar V.,Badjuk, Dalibor M.,Stevanovi?, Nenad,Pavlovi?, Radoslav Z.
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- Nickel-catalyzed decyanation of inert carbon-cyano bonds
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Nickel catalyzed decyanation of aryl and aliphatic cyanides with hydrosilane as the hydride source has been developed. This method is easy to handle, scalable and can be carried out without a glove box. The method has been applied in the cyanide directed functionalization reaction and α-substitution of benzyl cyanide.
- Patra, Tuhin,Agasti, Soumitra,Akanksha,Maiti, Debabrata
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supporting information
p. 69 - 71
(2013/02/21)
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- On the Mechanism of the Reduction of Primary Halides with Grignard Reagents in the Presence of (dppf)PdCl2 or (dppf)Pd(0)
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Reaction of primary alkyl halides with Grignard reagents in the presence (dppf)PdCl2 or (dppf)Pd(0) leads to reduction of the halide.The mechanism of the reduction is dependent on the solvent and the Grignard reagent.In tetrahydrofuran, reduction is independent of palladium.The alkyl halide is largely reduced by β-hydride transfer from the Grignard reagent.Competing with hydride transfer is a halogen-metal exchange reaction, which converts the alkyl halide into the corresponding Grignard reagent.Protonation of reaction mixture then gives the observed products.Grignard reagents that do not possess β-hydrogens undergo the halogen-metal exchange exclusively, but still lead to reduction of the alkyl halide.At subambient temperatures and in diethyl ether, reduction of primary alkyl halides with Grignard reagents in the absence of palladium catalysts is very slow.That reduction which does occur is almost exclusively the product of β-hydride transfer.The addition of (dppf)PdCl2 markedly accelerates the rate of reduction of alkyl halides in diethyl ether.The catalytic effect is proposed to occur through a catalytic cycle involving oxidative addition of the alkyl halide, hydride-transfer, and reductive-elimination steps.The order of the first two steps remains unclear.
- Yuan, Kaixu,Scott, William J.
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p. 6188 - 6194
(2007/10/02)
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