The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Robert J. Angelici - One of the best experts on this subject based on the ideXlab platform.
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bulk gold non nanogold catalysis of aerobic oxidations of Amines isocyanides carbon monoxide and carbene precursors
Catalysis Science & Technology, 2013Co-Authors: Robert J. AngeliciAbstract:Oxidative reactions that are catalysed by bulk gold consisting of ∼50000 nm gold powder particles or gold (∼50 nm) supported on Al2O3 are reviewed. Using O2 as the oxidizing agent, bulk gold catalyzes the following types of reactions in organic solvents at 45–90 °C: (1) the conversion of Amines to imines [(RCH2)2NH → RCH2NCHR], (2) the oxidation of benzyl alcohol to benzaldehyde, (3) the reaction of isocyanides with primary Amines to give carbodiimides [CN–R + H2N–R′ → R′–NCN–R] and with secondary Amines to give ureas , (4) the reactions of CO with primary Amines to give ureas [CO + H2N–R → OC(NHR)2], and (5) the reactions of diazoalkanes with Amines to give enAmines . In some of these reactions, Amine Oxides (e.g., Me3N–O) may be used in place of O2. Mechanisms of these and related reactions are exAmined. These studies show that bulk, non-nanogold is capable of catalysing a variety of different reactions.
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Bulk Gold-Catalyzed Oxidations of Amines and Benzyl Alcohol Using Amine N-Oxides as Oxidants
Catalysis Letters, 2012Co-Authors: Erik R. Klobukowski, Robert J. Angelici, L. Keith WooAbstract:Bulk gold powder (~50 μm) catalyzes the oxidative dehydrogenation of Amines to give imines using Amine N-Oxides (R_3N-O) as the oxidant. The reaction of dibenzylAmine (PhCH_2–NH–CH_2Ph) with N-methylmorpholine N-oxide (NMMO) in the presence of gold powder at 60 °C produced N-benzylidenebenzylAmine (PhCH=N–CH_2Ph) in 96% yield within 24 h. Benzyl alcohol was oxidized by NMMO to benzaldehyde in >60% yield in the presence of gold powder. Although O_2 was previously shown to oxidize Amines in the presence of bulk gold, it is surprising that gold is also capable of catalyzing the oxidation of Amines using Amine Oxides, which are chemically so different from O_2. Graphical Abstract
L. Keith Woo - One of the best experts on this subject based on the ideXlab platform.
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Bulk Gold-Catalyzed Oxidations of Amines and Benzyl Alcohol Using Amine N-Oxides as Oxidants
Catalysis Letters, 2012Co-Authors: Erik R. Klobukowski, Robert J. Angelici, L. Keith WooAbstract:Bulk gold powder (~50 μm) catalyzes the oxidative dehydrogenation of Amines to give imines using Amine N-Oxides (R_3N-O) as the oxidant. The reaction of dibenzylAmine (PhCH_2–NH–CH_2Ph) with N-methylmorpholine N-oxide (NMMO) in the presence of gold powder at 60 °C produced N-benzylidenebenzylAmine (PhCH=N–CH_2Ph) in 96% yield within 24 h. Benzyl alcohol was oxidized by NMMO to benzaldehyde in >60% yield in the presence of gold powder. Although O_2 was previously shown to oxidize Amines in the presence of bulk gold, it is surprising that gold is also capable of catalyzing the oxidation of Amines using Amine Oxides, which are chemically so different from O_2. Graphical Abstract
Kei Takeda - One of the best experts on this subject based on the ideXlab platform.
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Enantioselective preparation of N-chirogenic tertiary Amine Oxides
Tetrahedron Letters, 2007Co-Authors: Ichiro Suzuki, Ran Kerakawauchi, Takako Hirokawa, Kei TakedaAbstract:Abstract We found that PLE can be used as an efficient catalyst for desymmetrization of prochiral tertiary Amine N-Oxides and demonstrated that they were hydrolyzed by PLE efficiently to afford N -chirogenic tertiary Amine Oxides up to 99% ee in moderate to good yields.
José Elguero - One of the best experts on this subject based on the ideXlab platform.
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Theoretical Study of Strong Hydrogen Bonds between Neutral Molecules: The Case of Amine Oxides and Phosphine Oxides as Hydrogen Bond Acceptors
The Journal of Physical Chemistry A, 1999Co-Authors: Ibon Alkorta, José ElgueroAbstract:A theoretical study of the ability of Amine Oxides and phosphine Oxides as hydrogen bond (HB) acceptors has been carried out using ammonium oxide, trimethylAmine oxide, and phosphine oxide as model systems. The analysis of the energetic results indicate that only small spatial preferences are observed in the HB interaction. The value of the interaction energies are in several cases within the range of strong HB (>12 kcal/mol), and in complexes between Amine Oxides and strong acids in the gas phase, a spontaneous proton transfer is obtained. A logarithmic correlation between the electron density at the HB critical points and the HB distance that is able to fit not only calculated data but also experimental ones has been obtained. Finally, a linear relationship has been found between the number of HBs and the 31P NMR shielding in the H3PO···(HF)n series, in good agreement with experimental reports.
Nicolleta Gaggero - One of the best experts on this subject based on the ideXlab platform.
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Chiral t-butylphenylphosphinothioic acid in NMR analysis of tertiary Amine Oxides with a stereogenic nitrogen atom
Tetrahedron: Asymmetry, 1997Co-Authors: Józef Drabowicz, Bogdan Dudziński, Marian Mikołajczyk, Stefano Colonna, Nicolleta GaggeroAbstract:Abstract The enantiomers of tertiary Amine Oxides 3 show NMR spectral nonequivalence in the presence of (−)-(S)- or (+)-(R)-t-butylphenylphosphinothioic acid 4. It is observed even for the e-methyl protons and is large enough to determine the ee values of 3 having long alkyl chains. The enantiomeric thioacids 4 induce also an extremely large magnetic nonequivalence of the geminal N-methylene protons in 3.