Abstract |
This graduate Diploma Thesis consists of two parts.
In the First Part the biocatalytic reduction of carbon – carbon double bond of α,β-unsaturated carbonyl compounds and the enantioselective reduction of the keto group of α,β-unsaturated carbonyl compounds with isolated ketoreductases are presented.
In Chapter 1, the enantioselective reductions of α,β-unsaturated ketones, α,β-unsaturated 1,3-diketones, γ,δ-unsaturated β-ketoesters and ε,ζ-unsaturated β,δ-diketoesters yielding the corresponding hydroxy compounds with high optical purity are presented. These biocatalytic reductions gave optically active products in very good to high conversions (86 – 100%) and excellent optical purity (>99% ee).
In Chapter 2, the biocatalytic reduction of carbon–carbon double bonds of α,β-unsaturated ketones, α,β-unsaturated 1,3-diketones, γ,δ-unsaturated β-ketoesters and ε,ζ-unsaturated β,δ-diketoesters is presented. The enzymatically derived saturated products were formed in good to excellent yield.
Based on the differences in enzymatic activity of ketoreductases with the specific substrates described above, a new approach for the one pot conversion of γ,δ-unsaturated β-ketoesters to optically active saturated β-hydroxy esters, by the sequential use of two ketoreductases, is also presented.
In the Second Part, the oxidative cleavage of β-ketoesters and 1,3-diketones with a new system consisting of Oxone/AlCl3 in aqueous medium is first presented. In this oxidative cleavage process, safe and environmentally benign reagents were used. By this straightforward method, various simple α-ketoesters and 1,2-diketones were formed in excellent yields, after a simple purification process. The advantages of the methodology compared to the known synthetic routes are also presented.
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