- N,N-Dibromobenzenesulfonamide: A useful regenrable reagent for bromination of various carbanionic substrates
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N,N-Dibromobenzenesulfonamide(dibromoamine-B), which is prepared easily in high yield, has been employed as effective brominating agent for carbanionic substrates under mild conditions. β-Diketones and β-ketoesters were brominated by this reagent without using any bases. The reagent can be recovered, rebrominated, and reused several times.
- Tajbakhsh, Mahmood,Khazaei, Ardeshir,Mahalli, Majid Shabani,Vaghi, Ramin Ghorbani
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p. 1159 - 1163
(2007/10/03)
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- One-pot synthesis using supported reagents system: Conversion of β-dicarbonyl compounds to α-thiocyano-β-dicarbonyl compounds using CuBr2/Al2O3-KSCN/SiO2
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Transformation of β-dicarbonyl compound 1 to α-thiocyano-α-dicarbonyl compounds 3 in one-pot was achieved by using supported reagents system CuBr2/Al2O3 - KSCN/SiO2, in which 1 reacts first with CuBr2/Al2O3 and the product, α-bromo-β-dicarbonyl compound 2 reacts with KSCN/SiO2 to give the final product 3 in good yield.
- Suzuki, Yoshitada,Kodomari, Mitsuo
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p. 1091 - 1092
(2007/10/03)
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- Rate Constants for Halogen Atom Transfer from Representative α-Halocarbonyl Compounds to Primary Alkyl Radicals
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Rate constants for halogen atom transfer from diethyl methyliodomalonate (7a), iodoacetonitrile (7b), ethyl 2-methyl-2-iodopropanoate (7c), ethyl iodoacetate (7d), diethyl methylbromomalonate (7e), and ethyl bromoacetate (7f) to simple primary alkyl radicals have been studied by a variety of competition reactions.The Arrhenius functions for halogen atom transfer to the undecyl radical from halides 7d and 7f are log (kI, M-1 s-1) = 10.4 - 4.4/θ and log (kBr, M-1 s-1) = 10.4 - 8.2/θ, respectively.The rate constants for halogen atom transfer to a primaryradical from the series of compounds 7a-7f at 50 deg C are 1.8 x 109, 1.7 x 109, ca. 6 x 108, 2.6 x 107, 1.0 x 106, and 7.0 x 104 M-1 s-1, respectively.The kinetic values are useful for the planning of synthetic methods that incorporate an atom transfer-cyclization process.
- Curran, Dennis P.,Bosch, Eric,Kaplan, Jere,Newcomb, Martin
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p. 1826 - 1831
(2007/10/02)
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