Flow chemistry has been successfully integrated into the synthesis of a series of cyclooligomeric depsipeptides of three different ring sizes including the natural products beauvericin (1 a), bassianolide (2 b) and enniatin C (1 b). A reliable flow chemistry protocol was established for the coupling and macrocyclisation to form challenging N‐methylated amides. This flexible approach has allowed the rapid synthesis of both natural and unnatural depsipeptides in high yields, enabling further exploration of their promising biological activity.

Stereotriads bearing allylic alcohols are privileged structures in natural products, and new methods accessing these in a stereoselective fashion are highly sought after. Toward this goal, we found that the use of chiral polyketide fragments allows for performing the Hoppe−Matteson−Aggarwal rearrangement in the absence of sparteine with high yields and diastereoselectivities, rendering this protocol a highly valuable alternative to the Nozaki−Hiyama−Takai− Kishi reaction. The switch of directing groups in most cases resulted in the reversed stereochemical outcome, which could be explained by conformational analysis on density functional theory level and a Felkin-like model.

The first total synthesis of pericoannosin A (1) containing 15 steps in the longest linear sequence with an overall yield of 5.5% is reported. The hybrid peptide-polyketide was isolated from the endophytic fungus Periconia sp. F-31 and bears a unique tricyclic core structure. The key steps are a glycolate aldol reaction and a Diels-Alder reaction utilizing an Evans auxiliary for controlling the stereochemistry. Furthermore, a late-stage equilibration was employed.

The synthesis of desepoxy-tedanolide C was accomplished and provided experimental evidence on the configuration of tedanolide C. The reported chemical shifts and coupling constants point to a configuration different from the published structure and analogous to the structures of the other members of this family of natural products. The key step is a Kiyooka aldol protocol for the stereoselective synthesis of the tertiary alcohol flanked by three additional oxygenated carbon atoms. Furthermore, two additional aldol reactions and a Julia-Kocienski olefination were used to assemble the carbon framework.

A Kiyooka aldol approach for the stereoselective synthesis of tertiary alcohols is presented. This approach allows for the incorporation of different substituents at all three remaining positions at the chiral center bearing the tertiary alcohol. To demonstrate the validity of this approach different chiral alcohols were depicted and the relationship of double bond geometry of the ketene acetal and the diastereoselectivity was established.

Here we present our work on a Kiyooka aldol protocol for the stereoselective synthesis of tertiary alcohols. In the obtained products, three oxygenated carbon atoms that could further be differentiated flank the chiral tertiary alcohol. This methodology can be applied to simple aromatic or aliphatic aldehydes and more complex substrates bearing a chiral center in the α and/or β-position. For complex substrates, an unexpected dependency between stereoselectivity and double bond geometry of the ketene acetal was observed. Furthermore, applications in or towards the synthesis of natural products are presented. 1 Introduction 2 Scope of the reaction 3 Synthetic applications 4 Conclusion

The assignment of two stereocenters of the natural product haprolid through the application of a profile hidden Markov model (HMM) and its confirmation through total synthesis of the natural product and of two of its diastereomers are reported. The structure elucidation of this polyketide-peptide hybrid natural product is a telling showcase of how difficult it can be to determine the absolute configuration of isolated stereocenters and the benefits of a gene cluster analysis for structure determination. The key steps of the synthesis are a selective epoxidation of a terminal olefin and the stereodivergent macrolactonization strategy. Furthermore, the biological evaluation of all products showed that all diastereomers are potent inhibitors of hepatocellular carcinoma cell lines.

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