carried out most of his research at the Karlsruhe Institute of Technology (then, Technische Hochschule Karlsruhe), even after his retirementin1969 until his death on November 7, 1975. The renewed tremendous interest in ozone-organic chemistry is credited to R. Criegee, because of his pioneeringprecise investigations into the mechanism of the ozonolysis reaction. [6] Among Criegee's prolific scientific works, one of his great scientific achievements was the elucidation of the reaction mechanism of the ozonolysis of double bonds, [7] which has contributed enormouslyi ndifferent aspects to the progress of ozonation in organic chemistry. [8,9]
zu finden. 2020 Die Autoren. AngewandteChemie verçffentlichtv on Wiley-VCH GmbH. Dieser Open Access Beitrag steht unter den Bedingungen der Creative Commons Attribution Non-Commercial License, die eine Nutzung, Verbreitung und Vervielfältigung in allen Medien gestattet, sofern der ursprünglicheBeitrag ordnungsgemäß zitiert und nicht fürkommerzielle Zwecke genutzt wird.[*] Rudolf Criegee , Professorund Direktor des Instituts für Organische Chemie, forschte überwiegend am Karlsruher Institut für Technologie (damals Technische Hochschule Karlsruhe). Auch nach seiner Emeritierung im Jahr 1969 bis zu seinem Todam7.November 1975 galt seine Aufmerksamkeit der Forschung. Die Wiederbelebung des enormen Interesses an der Ozonchemiewird R. Criegee aufgrund seiner bahnbrechenden, präzisen Untersuchungen zum Mechanismusd er Ozonolyse zugeschrieben. [6] Unter Criegees produktiver wissenschaftlicher Arbeit war eine seiner großen Leistungen die Aufklärung des Reaktionsmechanismus fürdie Ozonolyse von Doppelbindungen, [7] die in verschiedener Hinsicht enorm zu ihrem Fortschritt in der organischen Chemie beigetragen hat. [8,9]
In this study, we report a convenient and high yielding formal semisynthesis of demethylgorgosterol, a marine steroid with an intriguing sidechain containing a cyclopropane unit. This was achieved through the synthesis of an advanced ketone intermediate. The synthetic route features a total of ten steps, starting from commercially available stigmasterol, with an overall yield of 27 %. The key step was a stereoselective intermolecular cyclopropanation reaction. This reaction proceeded in 82 % yield, the resulting cyclopropane carboxylic ester shows a trans/cis ratio of 89 : 11, with a diastereomeric ratio for the trans‐diastereomers of >99 : 1. A reduction/oxidation sequence afforded the corresponding aldehyde, which was used in a Grignard reaction. A final oxidation step then yielded the desired ketone. This novel route presents a platform to further investigate the medicinal applications of gorgosterol‐type steroids and to fully understand their role in coral symbiosis.
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