Novel double functional protection of cephalostatin analogues using a gas-free chlorination method

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Nawasreh, M.; Kirschning, A.; Duddeck, H.; Dräger, G.; Fenske, D.: Novel double functional protection of cephalostatin analogues using a gas-free chlorination method. In: Heliyon 6 (2020), Nr. 1, e03025. DOI: https://doi.org/10.1016/j.heliyon.2019.e03025

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Abstract: 
Herewith, we report on a method that allows to simultaneously protect both the ∆14,15 bond and the carbonyl group of the symmetrical bis-steroidal diketone 2. We found that environmentally friendly and gas-free chlorination is ideally suited to achieve this goal. This method was discovered during our efforts to methoxylate 2 in a solution of dichloromethane and basic methanol in the presence of diacetoxy iodobenzene. Unexpectedly, the ∆14,15 bonds were chlorinated once as well as twice in a statistical manner. Interestingly, the singly dichlorinated desymmetrized product is an ideal precursor for conduction a series of position selective transformations. Importantly, the carbonyl group present in the nonchlorinated hemisphere can be selectively reduced, olefinated or oximated, while the other carbonyl group stays unaltered. A structurally related “monomeric” steroid derivative undergoes ∆14,15 chlorination and 11-position methoxylation under same conditions. These findings represent a powerful entry for preparing new nonsymmetrical cephalostatin derivatives. © 2019
License of this version: CC BY-NC-ND 4.0 Unported
Document Type: Article
Publishing status: publishedVersion
Issue Date: 2020
Appears in Collections:Naturwissenschaftliche Fakultät

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pos. country downloads
total perc.
1 image of flag of Germany Germany 30 46.15%
2 image of flag of United States United States 17 26.15%
3 image of flag of China China 8 12.31%
4 image of flag of Jordan Jordan 4 6.15%
5 image of flag of Indonesia Indonesia 2 3.08%
6 image of flag of Taiwan Taiwan 1 1.54%
7 image of flag of Singapore Singapore 1 1.54%
8 image of flag of Netherlands Netherlands 1 1.54%
9 image of flag of Spain Spain 1 1.54%

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