Organocatalysis by Hydrogen Bonding Networks
In biological systems, hydrogen bonding is used extensively for molecular recognition, substrate binding, orientation and activation. In organocatalysis, multiple hydrogen bonding by man-made catalysts can effect remarkable accelerations and selectivities as well. The lecture presents four examples of non-enzymatic (but in some cases enzyme-like!) catalysis effected by hydrogen bonding networks: epoxidation of olefins and Baeyer–Villiger oxidation of ketones with H2O2 in fluorinated alcohol solvents; peptide-catalyzed asymmetric epoxidation of enones by H2O2; dynamic kinetic resolution of azlactones, affording enantiomerically pure α-amino acids; and kinetic resolution of oxazinones, affording enantiomerically pure β-amino acids. All four types of transformations are of preparative value, and their mechanisms are discussed.
KeywordsCarbonyl Oxygen Atom Oxyanion Hole Amino Acid Amide Crude Reaction Mixture Multiple Hydrogen Bonding
This work was supported financially by the EU (Research Training Networks ‘The Discovery of New Molecular Catalysts through Combinatorial Chemistry: Activity and Selectivity from Diversity’, COMBICAT, RTN-CT-2000–00014 and ‘(R)Evolutionary Catalysis’, REVCAT, MRTN-CT-2006–038566), the Deutsche Forschungsgemeinschaft (Priority Program ‘Organocatalysis’, SPP 1179), the Fonds der Chemischen Industrie, and by the BASF AG, Ludwigshafen. Generous gifts of amino acids by the Degussa AG, Hanau, are gratefully acknowledged.
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