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          Institute: MPI für Kohlenforschung     Collection: Publikationen MPI für Kohlenforschung     Display Documents

ID: 19890.0, MPI für Kohlenforschung / Publikationen MPI für Kohlenforschung
Total synthesis of (S)-(+)-citreofuran by ring closing alkyne metathesis
Authors:Fürstner, A.; Castanet, A. S.; Radkowski, K.; Lehmann, C. W.
Date of Publication (YYYY-MM-DD):2002-02-21
Title of Journal:Journal of Organic Chemistry
Journal Abbrev.:J. Org. Chem.
Issue / Number:4
Start Page:1521
End Page:1528
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:A concise total synthesis of citreofuran 4 is described, a structurally unique octaketide derivative belonging to the curvularin family. Key steps involve the elaboration of orsellinic acid methyl ester 5 to acid 14, which converts, on attempted formation of the corresponding acid chloride, to the 3-alkoxyisocoumarin derivative 20. This heterocycle can be used as an activated ester to give ketone 21 on treatment with 3- pentynylmagnesium bromide in the presence of TMSCl as the activating agent. Ring- closing alkyne metathesis (RCAM) of diyne 21 catalyzed by (tBuO)(3)Wequivalent toCCMe(3) affords the strained cycloalkyne 22. Treatment with acid renders its triple bond susceptible to nucleophilic attack by the adjacent carbonyl group, thus leading to a transannular cycloaromatization with formation of the intact skeleton of citreofuran. An X-ray crystallographic study reveals conformational. details about this natural product. Finally, it is shown that 4 as well as its protected precursor 23 are able to cleave double-stranded DNA under oxidative conditions.
Comment of the Author/Creator:Date: 2002, FEB 21
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Kohlenforschung
Identifiers:ISI:000181061700044 [ID No:1]
ISSN:0022-3263 [ID No:2]
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