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Third-party-funded project

Title:
Use of lipoxygenase and peroxidase for selective catalyses in the organic synthesis

Project management at the University of Würzburg:

Participating scientists:

Abstract:
In the lipoxygenase (LOX) oriented part, the potential of the soybean isoenzyme L-1 for the regio- and enantioselective dioxygenation of phenolic 1,4-(Z,Z)-alkadienes and -alkatrienes was studied. Using various synthesized substrates and the natural cardanoldiene selective LOX catalysis was realized. The length of the alkadiene(triene) residue was found to be important for the effectivity; highest kcat values were obtained for substrates with a linoleic acid-analogous side chain. Even arylalkenones, which a priori are not in agreement with the established catalytic LOX mechanism, were transformed by L-1. Using curcumin as substrate, three novel bicyclic products were described for the first time.

In the peroxidase (POD) oriented part, the potential of horseradish peroxidase (HRP) for the enantioselective reduction of racemic alkyl aryl hydroperoxides was studied. The results of kinetic resolutions showed that HRP reduced sterically unhindered hydroperoxides with high enantioselectivity, resulting in the formation of optically active hydroperoxides and alcohols with enantiomeric excesses from 80-100%. The chiral recognition was limited in case of sterical hindering in the alkyl chain and with alpha-functionalized hydroperoxides. Tertiary hydroperoxides were not accepted as substrates. In addition, HRP was found to be an effective, but unselective catalyst for biaryl synthesis.

In all the studies chromatographic methods and the exciton coupled circular dichroism (ECCD) technique were used for the stereocontrol and the determination of absolute configurations.

Key words:
    Lipoxygenase
    Peroxidase
    Dioxygenation
    Horseradish peroxidase
    Cardanoldiene
    Arylalkenone
    Kinetic resolution
    Hydroperoxides
    Curcumin
    Chirale Analyse
    Exciton circular dichroism
    Biaryl synthesis

Projekt period: from 01.1996 to 12.1998

Funding institution:
DFG ,Granting date: 01.10.1995

Publications:

Links:
Research area