Chloroperoxidase-catalyzed enantioselective oxidations in hydrophobic organic media.
Chloroperoxidase from Caldariomyces fumago, a peroxidase that performs P450-like chemistry, was immobilized via covalent attachment into polyurethane foam as well as conjugated with a surfactant or polymer via colyophilization. The resulting preparations catalyzed enantio- and regioselective oxidations in hydrophobic organic media with tert-butyl hydroperoxide as the oxidant. Dried PUR-foam immobilized CPO mediated the selective oxidation of indole to 2-oxindole (regioselectivity: 99%) in water-saturated isooctane or 1-octanol. Thioanisole was converted into the corresponding (R)-sulfoxide (ee > 99%) in isooctane medium. The complexes of CPO with sodium octadecylsulphate or ethyl cellulose mediated the oxidation of thioanisole in water-immiscible organic media with variable enantioselectivity due to radical side-reactions. In the presence of alpha-tocopherol, acting as radical scavenger, the (R)-sulfoxide was formed with ee > 90%. The effect of the water activity on the catalytic activity of the complexes was investigated. The CPO complexes likewise mediated the regioselective oxidation of indole into 2-oxindole in water-saturated isooctane or 1-octanol and its kinetics were investigated. The reaction suffered from substrate inhibition when carried out in isooctane.
van de Velde
F
F
Laboratory of Organic Chemistry and Catalysis, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands. Secretariat-OCK@tnw.tudelft.nl
Bakker
M
M
van Rantwijk
F
F
Sheldon
R A
RA
D002384:Catalysis; D002711:Chloride Peroxidase / Q000378:metabolism*; D003470:Culture Media; D004789:Enzyme Activation; D007211:Indoles; D007536:Isomerism; D007700:Kinetics; D010084:Oxidation-Reduction; D011108:Polymers; D011140:Polyurethanes; D012997:Solvents / Q000737:chemistry; D013440:Sulfides / Q000378:metabolism; D013455:Sulfur; D013501:Surface-Active Agents; D014867:Water / Q000737:chemistry; D020122:tert-Butylhydroperoxide / Q000378:metabolism
D003470:Culture Media; D007211:Indoles; D011108:Polymers; D011140:Polyurethanes; D012997:Solvents; D013440:Sulfides; D013501:Surface-Active Agents; D014867:Water; D013455:Sulfur; C030374:indole; D020122:tert-Butylhydroperoxide; C093850:methylphenylsulfide; D002711:Chloride Peroxidase