Asymmetrische Synthesen von Attenol A und B 1 (+)-Strictifolion und des 1-epi-Aglycons der Cripowelline A und B

The isomeric polyketides attenol A and B, which were isolated by Suenaga et al. in 1999 from the Chinese bivalve Pinna attenuata, exhibit interesting cytotoxicity against P388 cells. This renders them interesting synthetic targets. We were able to develop a convergent and highly stereoselective (de, ee >= 96%) synthesis of both attenols offering the possibility to synthesize different derivatives. Key steps in our approach were highly stereoselective alkylations of SAMP-hydrazones and an asymmetric Sharpless-dihydroxylation. In 2000 Aimi et al. were able to isolate (+)-strictifolione from stem bark of the tree Cryptocarya strictifolia. In cooperation with Müller from the FZ Jülich we succeeded in the development of a highly stereoselective total synthesis (de = 89%, ee >= 96%) of this natural product. A slightly modified approach resulted in a formal synthesis being superior to the aforementioned total synthesis in terms of stereoselectivity (de, ee >= 96%). In 1997 coworkers of the former Bayer AG reported on two new Amaryllidaceae-alkaloids, cripowellin A and B, which had been isolated from bulbs and roots of Crinum powellii. Their aglycon consists of a [5.3.2]-bicyclic core, an unprecedented structure among the Amaryllidaceae-alkaloids. In addition, both the cripowellins and their aglycon exhibit high insecticidal activity. Our approach yielded the 1-epi-aglycon in a highly stereoselective fashion (de, ee >= 98%). Key steps were a highly enantioselective Sharpless-dihydroxylation, a ring closing metathesis and a highly diastereoselective intramolecular Heck-reaction. Careful analysis of the X-ray structure of the bisacetylated 1-epi-aglycon revealed that it probably exhibits the same biological activity as the natural aglycon itself.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2005

Author dc:creator

• Lenzen, Achim

Contributors dc:contributor

• Enders, Dieter

• info:eu-repo/classification/ddc/540
• Cripowellin A
• Cripowellin B
• Aglykon
• Attenole
• Totalsynthese
• Strictifolion
• Asymmetrische Synthese
• Chemie
• Naturstoffe

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123695%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62101