- A novel method of arylation of α-chloroketones
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α-Arylated ketones were obtained in moderate to good yields by one-step electroreductive coupling of α-chloroketones and arylhalides in DMF and in the presence of a Al- or Zn-sacrificial anode and a catalytic amount of a nickel complex.
- Durandetti,Sibille,Nedelec,Perichon
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- Regioselective 1,2-Diol Rearrangement by Controlling the Loading of BF3·Et2O and Its Application to the Synthesis of Related Nor-Sesquiterene- and Sesquiterene-Type Marine Natural Products
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The regiocontrolled rearrangement of 1,2-diols has been achieved by controlling the loading of BF3·Et2O. Its applicability is showcased by the divergent synthesis of austrodoral, austrodoric acid, and 8-epi-11-nordriman-9-one, as well as a formal synthesis of siphonodictyal B and liphagal. A new light is shed on piancol-type rearrangements that will be useful in diversity-oriented synthesis of related natural products.
- Wang, Jun-Li,Li, Hui-Jing,Wang, Hong-Shuang,Wu, Yan-Chao
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p. 3811 - 3814
(2017/07/26)
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- Control of the Chemoselectivity of Metal N-Aryl Nitrene Reactivity: C-H Bond Amination versus Electrocyclization
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A mechanism study to identify the elements that control the chemoselectivity of metal-catalyzed N-atom transfer reactions of styryl azides is presented. Our studies show that the proclivity of the metal N-aryl nitrene to participate in sp3-C-H bond amination or electrocyclization reactions can be controlled by either the substrate or the catalyst. Electrocyclization is favored for mono-β-substituted and sterically noncongested styryl azides, whereas sp3-C-H bond amination through an H-atom abstraction-radical recombination mechanism is preferred when a tertiary allylic reaction center is present. Even when a weakened allylic C-H bond is present, our data suggest that the indole is still formed through an electrocyclization instead of a common allyl radical intermediate. The site selectivity of metal N-aryl nitrenes was found to be controlled by the choice of catalyst: Ir(I)-alkene complexes trigger electrocyclization processes while Fe(III) porphyrin complexes catalyze sp3-C-H bond amination in substrates where Rh2(II) carboxylate catalysts provide both products.
- Kong, Chen,Jana, Navendu,Jones, Crystalann,Driver, Tom G.
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supporting information
p. 13271 - 13280
(2016/10/22)
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- Hiyama reactions of activated and unactivated secondary alkyl halides catalyzed by a nickel/norephedrine complex
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(Chemical Equation Presented) An active partner: Nickel in combination with an amino alcohol ligand (norephedrine) was found to provide the most versatile and efficient catalyst for Hiyama cross-coupling reactions of alkyl electrophiles that has been described to date. Unprecedented Hiyama reactions of activated secondary alkyl bromides were achieved, as were the first Hiyama couplings of (activated) alkyl chlorides (see scheme, X = Br, Cl; HMDS = 1,1,1,3,3,3-hexamethyldisilazane, DMA = N,N-dimethylacetamide).
- Strotman, Neil A.,Sommer, Stefan,Fu, Gregory C.
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p. 3556 - 3558
(2008/02/14)
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- Nickel-catalyzed direct electrochemical cross-coupling between aryl halides and activated alkyl halides
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The electrochemical reduction of a mixture of aryl halides and activated alkyl halides in DMF in the presence of catalytic amount of NiBr2bipy leads to cross-coupling products in good to high yields. The method applies to the synthesis of α-aryl ketones, α-aryl esters, and allylated compounds from readily available organic halides. Optimization of the process has been obtained by slowly adding the most reactive organic halide (usually the activated alkyl halide) during the electrolysis which is best conducted at 70 °C when aryl bromides are involved.
- Durandetti, Muriel,Nedelec, Jean-Yves,Perichon, Jacques
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p. 1748 - 1755
(2007/10/03)
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- New Method for Generation of β-Oxido Carbenoid via Ligand Exchange Reaction of Sulfoxides: A Versatile Procedure for One-Carbon Homologation of Carbonyl Compounds
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A new procedure for one-carbon homologation of carbonyl compounds is described.The method is based on the rearrangement of β-oxido carbenoid which is generated via the ligand exchange reaction of the sulfinyl group of α-chloro β-hydroxy sulfoxide with tert-butyllithium.Addition of the carbanion of aryl 1-chloroalkyl sulfoxides to carbonyl compounds gave the adducts in good yields.The β-oxido carbenoid rearrangement of the adducts gave one-carbon homologated carbonyl compounds having an α-alkyl substituent.A similar reaction of the adducts derived from carbonyl compounds with chloromethyl p-tolyl sulfoxide yielded a procedure for a methylene insertion.The stereochemistry of the β-oxido carbenoid rearrangenment is also discussed.
- Satoh, Tsuyoshi,Itoh, Norifumi,Gengyo, Kaoru,Takada, Sae,Asakawa, Naoyuki,et al.
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p. 11839 - 11852
(2007/10/02)
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- The Allopolarization Principle and its Applications, IV. Substituent Effects in the Methylation of Enolate Anions
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The ratio of O- and C-methylated products in the reaction of the sodium salts of acetophenones 1, propiophenones 3, phenylacetones 5, β-dicarbonyl compounds 12, α-cyanocarbonyl compounds 13, acetaldehyde, propionaldehyde, and diethylketone with dimethyl sulfate, methyl iodide, and trimethyl phosphate in HMPTA has been determined with regard to the effect of substituents.In some cases the influence of solvents, concentration and temperature has also been studied.
- Gompper, Rudolf,Vogt, Hans-Hubert
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p. 2866 - 2883
(2007/10/02)
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