publications of the department medicinal chemistry (MCH)
http://hdl.handle.net/10033/620654
2024-03-03T01:21:14Z
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Contiguous Quaternary Carbons: A Selection of Total Syntheses.
http://hdl.handle.net/10033/623229
Contiguous Quaternary Carbons: A Selection of Total Syntheses.
Eggert, Alina; Etling, Christoph; Lübken, Dennis; Saxarra, Marius; Kalesse, Markus
Contiguous quaternary carbons in terpene natural products remain a major challenge in total synthesis. Synthetic strategies to overcome this challenge will be a pivotal prerequisite to the medicinal application of natural products and their analogs or derivatives. In this review, we cover syntheses of natural products that exhibit a dense assembly of quaternary carbons and whose syntheses were uncompleted until recently. While discussing their syntheses, we not only cover the most recent total syntheses but also provide an update on the status quo of modern syntheses of complex natural products. Herein, we review (±)-canataxpropellane, (+)-waihoensene, (-)-illisimonin A and (±)-11-O-debenzoyltashironin as prominent examples of natural products bearing contiguous quaternary carbons.
2020-08-24T00:00:00Z
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Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment.
http://hdl.handle.net/10033/623186
Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment.
Geldsetzer, Jan; Kalesse, Markus
The stereoselective synthesis of the (Z)-enamide fragment of chondrochloren (1) is described. A Buchwald-type coupling between amide 3 and (Z)-bromide 4 was used to generate the required fragment. The employed amide 3 comprising three chiral centers was obtained through a seven-step sequence starting from ᴅ-ribonic acid-1,4-lactone. The (Z)-vinyl bromide 4 is accessible in four steps from 4-hydroxybenzaldehyde. The pivotal cross coupling between both fragments was achieved after extensive experimentation with copper(I) iodide, K2CO3 and N,N'-dimethylethane-1,2-diamine.
2020-04-14T00:00:00Z
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Recent Applications of the Diels-Alder Reaction in the Synthesis of Natural Products (2017-2020)
http://hdl.handle.net/10033/623053
Recent Applications of the Diels-Alder Reaction in the Synthesis of Natural Products (2017-2020)
Sara, Alexandru A.; Um-E-Farwa, Um E.Farwa; Saeed, Aamer; Kalesse, Markus
The Diels-Alder reaction has long been established as an extremely useful procedure in the toolbox of natural product chemists. It tolerates a wide spectrum of building blocks of different complexity and degrees of derivatization, and enables the formation of six-membered rings with well-defined stereochemistry. In recent years, many total syntheses of natural products have been reported that rely, at some point, on the use of a [4+2]-cycloaddition step. Among classic approaches, several modifications of the Diels-Alder reaction, such as hetero-Diels-Alder reactions, dehydro-Diels-Alder reactions and domino-Diels-Alder reactions, have been employed to extend the scope of this process in the synthesis of natural products. Our short review covers applications of the Diels-Alder reaction in natural product syntheses between 2017 and 2020, as well as selected methodologies which are inspired by, or that can be used to access natural products. 1 Introduction 2 Syntheses from 2017 3 Syntheses from 2018 4 Syntheses from 2019 5 Syntheses from 2020 6 Conclusion. © 2021 Georg Thieme Verlag. All rights reserved
2021-06-21T00:00:00Z
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Synthesis of Desepoxy-Tedanolide C.
http://hdl.handle.net/10033/622876
Synthesis of Desepoxy-Tedanolide C.
Lücke, Daniel; Kalesse, Markus
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.
2021-04-09T00:00:00Z