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

ID: 20055.0, MPI für Kohlenforschung / Publikationen MPI für Kohlenforschung
Total syntheses of the phytotoxic lactones herbarumin I and II and a synthesis-based solution of the pinolidoxin puzzle
Authors:Fürstner, A.; Radkowski, K.; Wirtz, C.; Goddard, R.; Lehmann, C. W.; Mynott, R.
Date of Publication (YYYY-MM-DD):2002-06-19
Title of Journal:Journal of the American Chemical Society
Journal Abbrev.:J. Am. Chem. Soc.
Issue / Number:24
Start Page:7061
End Page:7069
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:A concise approach to a family of potent herbicidal 10-membered lactones is described on the basis of ring-closing metathesis (RCM) as the key step for the formation of the medium-sized ring. This includes the first total syntheses of herbarumin I (1) and II (2) as well as the synthesis of several possible macrolides of the pinolidoxin series, A comparison of their spectral and analytical data with those of the natural product allowed us to establish the stereostructure of pinolidoxin, a potent inhibitor of induced phenylalanine ammonia lyase (PAL) activity, as shown in 46. This finding, however, makes clear that a previous study dealing with the relative and absolute stereochemistry of this phytotoxic agent cannot be correct. An important aspect from the preparative point of view is the fact that the stereochemical outcome of the RCM reaction can be controlled by the choice of the catalyst. Thus, use of the ruthenium indenylidene complex 16 always leads to the corresponding (E)-alkenes, whereas the second generation catalyst 17 bearing an N-heterocyclic carbene ligand affords the isomeric (2)-olefin with good selectivity. This course is deemed to reflect kinetic versus thermodynamic control of the cyclization reaction and therefore has potentially broader ramifications for the synthesis of medium-sized rings in general. A further noteworthy design feature is the fact that D-ribose is used as a convenient starting material for the preparation of both enantiomers of the key building block 14 by means of a "head-to-tail" interconversion strategy.
Comment of the Author/Creator:Date: 2002, JUN 19
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Kohlenforschung
Identifiers:ISI:000176198200053 [ID No:1]
ISSN:0002-7863 [ID No:2]
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