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Pericyclic reactions in the biomimetic total synthesis of natural products

Posted on:2007-05-23Degree:Ph.DType:Thesis
University:University of California, BerkeleyCandidate:Malerich, Jeremiah PeterFull Text:PDF
GTID:2441390005965774Subject:Chemistry
Abstract/Summary:PDF Full Text Request
Biomimetic strategies have often proven to be effective for the synthesis of natural products. Those incorporating pericyclic reactions are particularly efficient and elegant. In this vein, we embarked upon syntheses of naphthoquinones isolated from Bignoniaceae and the sesquiterpene xanthipungolide.; A unified biosynthetic proposal was advanced which served as the basis for our retrosynthesis of a class of naphthoquinones from Bignoniaceae. This proposal featured electrocyclizations, cycloadditions, and cycloreversions. The accompanying synthetic study resulted in the total syntheses of pinnatal, isopinnatal, sterekunthals A and B, pyranokunthones A and B, anthrakunthone, and sterequinone F. In turn, the success of these efforts lends credence to the proposed biosynthesis.; Two strategies for the asymmetric synthesis of xanthipungolide were attempted. Both employed an Evans aldol reaction to establish the absolute stereochemistry of the natural product. The first strategy centered upon an enyne/cross-metathesis cascade for the synthesis of the putative biosynthetic precursor of xanthipungolide. The second strategy sought to utilize a photocycloaddition/electrocyclic ring opening sequence.; Finally, progress toward the asymmetric synthesis of candelalide A is presented also. An advanced intermediate containing all five stereocenters of the natural product has been prepared, and this compound is suitably functionalized for completion of the synthesis.
Keywords/Search Tags:Synthesis, Natural
PDF Full Text Request
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