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Identifier

000367384

Title

Βιοκαταλυτικές αναγωγές β,δ-δικέτο εστέρων

Alternative Title

Biocatalytic reductions of β,δ-diketo esters

Author

Μπαριωτάκη, Αννα Βασ.

Thesis advisor

Σμόνου, Ιουλία

Abstract

In the present thesis the stereoselective enzymatic reductions with NADPH-dependent ketoreductases for the synthesis of important chiral intermediates were studied and more specifically for the synthesis of optically pure hydroxy-keto esters and 1,3-diols. Also, the chemoenzymatic synthesis of the natural product “Parasorbic acid” has been accomplished. All products derived from enzymatic reductions were analyzed and characterized. Their absolute configuration was determined by NMR spectroscopy. The first study included the one step enzymatic reduction for the first time in the literature of tert-butyl 3,5-dioxo-hexanoate for the synthesis of 5-hydroxy-3-keto esters and 3-hydroxy-5-keto esters. These products were synthesized with excellent optical and chemical purity. Ketoreductases proved to be excellent catalysts with high stereoselectivity and chemoselectivity. The next study included the two step enzymatic reduction of tert-butyl 3,5-dioxo-hexanoate for the synthesis of 3,5-dihydroxy-keto esters. The results here showed excellent optical and chemical purity of the products as well as high enantiomeric and diastereomeric excess. Based on the above results, the two step, one-pot enzymatic reduction of tert-butyl 3,5-dioxo-hexanoate for the direct synthesis of optically pure 3,5-dihydroxy-keto esters was accomplished successfully. In this process the two reductive steps were performed in the same reaction vessel without the isolation of the intermediate hydroxy-keto ester. Ketoreductases showed excellent stereoselectivity and chemoselectivity in the one-pot, two step enzymatic process. In the last part of this thesis, the chemoenzymatic synthesis of the natural product “Parasorbic acid” in high optical and chemical purity, is presented.

Language

Greek

Subject

3,5-διοξο-εξανικός τριτ-βουτηλεστέρας

Cascade

Dihydroxy-keto esters

Enzymatic reducton

Hydroxy-keto esters

Ketoreductases

Parasorbic acid

Tert-butyl 3,5-dioxo-Hexanoate

Διυδροξύ-κετοεστέρες