Totalsynthese von Preussochromon D & Beiträge zur Totalsynthese von Preussochromon E & F

In this work, the first enantioselective total synthesis of preussochromone D was developed, yielding the preussochromone in 15% overall yield over 9 steps. Key step of the synthesis was a highly diastereoselective intramolecular aldol reaction between a benzylic keton and an α-keto-β-hydroxyester moiety. Besides the natural product, four additional epimers of Preussochromone D and F were synthesized and fully characterized. During the total synthesis of Preussochomone D, multiple highly diastereoselective intramolecular aldol additions and aldol condensations of chromanones to α,β-diketo esters and α-keto- β-hydroxy esters were developed. These implementations allow the stereoselective synthesis of different, highly substituted tetrahydrocyclopenta[b]chromanones and represent a modular synthetic strategy as compared to those known in literature.