Asymmetrische Synthese von Synargentolid A und Studien zur Synthese von Invictolid sowie Ieodomycin A und B

The goal of this thesis was the asymmetric synthesis of natural products. These were Synargentoide A, Invictolide and the Ieodomycins A and B. The SAMP/RAMP methodology was used to create two or three of the streogenic centers in each of those molecules with a high selectivity. The synthesis of Synargentolide A was successfully finished during this thesis. First a bisalkylated ketone was synthesized from 2,2-dimethyl-1,3-dioxanone using the RAMP hydrazon methodology in good yields and excellent selectivity. No method was found for a diastereoselective reduction of this ketone but separation of the two diastereomer by HPLC was possible. This led to the synthesis of a triacetate in two steps. After cross metathesis with acrolein the aldehyde was synthesized. From this aldehyde the delta-lacton unit could be constructed. After stereoselective allylation and esterification the final product was obtained in 77% yield after a ring closing metathesis. The overall yield was 9 % after 11 steps. The 3-epimer was also synthesized in slightly lower yields of 7% overall. The synthesis of Invictolide and the Ieodomycins A and B was not successfully finished during this thesis