[reaction: see text]. An operationally simple and recoverable fluorous CBS methodology was developed. The in situ-generated fluorous oxazaborolidine efficiently catalyzed the reduction of ketones with high enantioselectivity and reactivity. The subsequent recycling of the fluorous prolinol precatalyst was achieved by fluorous solid-phase extraction.
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Molecules
March 2021
Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
The reaction of [PdCl(CHCN)] and bis-4,4'-(RCHOCH)-2,2'-bpy (), where R = -CF (), -CF (), -CF () and -CF (), respectively, in the presence of dichloromethane (CHCl) resulted in the synthesis of Pd complex, [PdCl[4,4'-bis-(RCHOCH)-2,2'-bpy] (). The Pd-catalyzed Stille arylations of vinyl tributyltin with aryl halides were selected to demonstrate the feasibility of recycling usage with as the catalyst using NMP (N-methyl-2-pyrrolidone) as the solvent at 120-150 °C. Additionally, recycling and electronic effect studies of were also carried out for Suzuki-Miyaura reaction of phenylboronic acid derivatives, 4-X-CH-B(OH), (X = H or Ph) with aryl halide, 4-Y-CH-Z, (Y = CN, H or OCH; Z = I or Br) in dimethylformamide (DMF) at 135-150 °C.
View Article and Find Full Text PDFMolecules
February 2021
Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 106, Taiwan.
Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucleophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles can be combined with each other. This offers the possibility to access many diversely functionalized products. In this work, two kinds of basic pyridine-based organo-catalysts were used to efficiently catalyze phospha-Michael addition reactions, the 4-,-dimethylaminopyridinium saccharinate (DMAP·Hsac) salt and a fluorous long-chained pyridine (4--CHOCH-py, where = CF).
View Article and Find Full Text PDFBiotechnol Prog
May 2009
Interdisciplinary Nanoscience Center (iNANO), Dept. of Physics and Astronomy, The Faculty of Science, University of Aarhus, Denmark.
The formation of noncovalent complexes between lipase from Burkholderia cepacia and the fluorinated ionic surfactant Kryto Development Product 4606 KDP was shown to promote the solubilization of the enzyme in the fluorinated solvent perfluoro(methylcyclohexane) (PFMC) and its operation as a catalyst in the fluorous PFMC/hexane biphasic system (FBS). In the reaction of esterification of 1-phenylethanol and vinyl acetate, the solubilized lipase showed high stereospecificity (ca. 99%) with a catalytic efficiency up to 56 nmol/(U h) with a high operational and storage stability.
View Article and Find Full Text PDFChem Asian J
October 2008
Institut für Organische Chemie and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
Solutions of the fluorous alkyl halides R(f8)(CH(2))(m)X (R(fn)=(CF(2))(n-1)CF(3); m=2, 3; X=Cl, Br, I) in perfluoromethylcyclohexane or perfluoromethyldecalin are inert towards solid or aqueous NaCl, NaBr, KI, KCN, and NaOAc. However, halide substitution occurs in the presence of fluorous phosphonium salts (R(f8)(CH(2))(2))(R(f6)(CH(2))(2))(3)P(+)X(-) (X=I (1), Br (3)) and (R(f8)(CH(2))(2))(4)P(+)I(-) (10 mol %), which are soluble in the fluorous solvents under the reaction conditions (76-100 degrees C). Stoichiometric reactions of a) 1 with R(f8)(CH(2))(2)Br and b) 3 with R(f8)(CH(2))(2)I were conducted under homogenous conditions in perfluoromethyldecalin at 100 degrees C and yielded the same R(f8)(CH(2))(2)I/R(f8)(CH(2))(2)Br equilibrium ratio ( approximately 60:40).
View Article and Find Full Text PDFOrg Lett
July 2005
Institute of Biomolecular Chemistry, Chemical Research Center of Hungarian Academy of Science, Budapest.
[reaction: see text]. An operationally simple and recoverable fluorous CBS methodology was developed. The in situ-generated fluorous oxazaborolidine efficiently catalyzed the reduction of ketones with high enantioselectivity and reactivity.
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