- Asymmetric Halogenation and Hydrohalogenation of trans-2-Butenoic Acid in a Crystalline α-Cyclodextrin Complex
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trans-2-Butenoic acid was asymmetrically hydrohalogenated and halogenated in a crystalline α-cyclodextrin complex.Exposure to gaseous hydrogen bromide at 20 deg C and to hydrogen chloride at 0 deg C gave (S)-(+)-3-bromobutanoic acid in 58percent and (S)-(-)-3-chlorobutanoic acid in 64percent enantiomeric excesses, respectively.At 45-50 deg C, the guest in the cavity of the cyclodextrin reacted with gaseous bromine or chlorine to produce erythro-dihalides with extremely low optical activities; no products were obtained on treatment with bromine for 50 h at the lower temperatureof 20 deg C.The crystal structure of the complex was determined to be: C36H60O30*C4H6O2*5H2O; FW = 1149.0; orthorhombic; space group, P212121; Z = 4; a = 14.406 (5), b = 38.174 (12), and c = 9.430 (3) Angstroem; V = 5185.9 Angstroem3; Dx = 1.472, Dm = 1.475 g/cm2.A mechanism for the observed chiral induction in the present gas-solid reaction is discussed in terms of the crystal structure of the complex.
- Tanaka, Yoshio,Sakuraba, Hidetake,Nakanishi, Hachiro
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- Nucleophilic halo-michael addition under lewis-base activation
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A simple and general conjugate nucleophilic halogenation is presented. The THTO/halosilane combination has shown the ability to act as a nucleophilic halide source in the conjugate addition to a variety of Michael acceptors. In addition, a straightforward diastereoselective halogen installation using α,β-unsaturated acyloxazolidinones as platforms has been developed.
- Laina-Martín, Víctor,Pérez, Ignacio,Fernández-Salas, Jose A.,Alemán, José
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supporting information
p. 12936 - 12939
(2019/11/05)
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- COMPOSITIONS USEFUL IN THERAPY OF AUTOPHAGY-RELATED PATHOLOGIES, AND METHODS OF MAKING AND USING THE SAME
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Lanthionine ketimine phosphonate (LK-P), lanthionine ketimine ester phosphonate (LKE-P), other lanthionine ketimine, lanthionine ketimine phosphonate, and lanthionine ketimine ester derivatives, and methods of making and using the same, are described.
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Paragraph 00266; 00267
(2018/09/19)
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- Allylsilane-interrupted homo-Nazarov cyclization and synthesis of bicyclo[3.2.1]octan-8-ones
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The combination of homo-Nazarov cyclization of 2-(tert- butyldiphenylsilylmethyl)cyclopropyl vinyl ketone leading to oxyallyl cation and its subsequent [3+2] capture by allylsilane has been demonstrated as an useful strategy for the construction of functionalized bicyclo[3.2.1]octan-8-ones. The [3+2] capture proceeds exclusively in the exo mode to make the overall reaction diastereoselective. The less substituted end of the oxyallyl cation was found to react nearly two times faster than the more substituted end.
- Yadav, Veejendra K.,Naganaboina, Vijaya K.,Hulikal, Vijaykumar
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supporting information
p. 2015 - 2018
(2014/04/03)
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- Intramolecular homolytic substitution of sulfinates and sulfinamides
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A general and efficient method for the synthesis of cyclic sulfi-nates and sulfinamides based on intra-molecular homolytic substitution (SHi) at the sulfur atom by aryl or alkyl radi-cals is described. Both alkyl and benzo-fused compounds can be accessed di-rectly from easily prepared acyclic pre-cursors. Enantiomerically enriched sulfur-based heterocycles were formed through an SHi process with inversion of configuration at the sulfur atom. Cyclization of prochiral radicals proceeded with varying stereochemical outcomes, depending on the size of the incoming radical. 2-Pyridyl and 2-qui-nolyl radicals led to biaryl compounds, which result from attack onto the ortho position of the arylsulfinate rather than a thiophilic substitution.
- Coulomb, Julien,Certal, Victor,Larraufie, Marie-Helene,Ollivier, Cyril,Corbet, Jean-Pierre,Mignani, Gerard,Fensterbank, Louis,Lacote, Emmanuel,Malacria, Max
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supporting information; experimental part
p. 10225 - 10232
(2010/04/05)
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