Qu P, Snyder SA. Concise and Stereoselective Total Syntheses of Annotinolides C, D, and E.
J Am Chem Soc 2021;
143:11951-11956. [PMID:
34338524 PMCID:
PMC8397315 DOI:
10.1021/jacs.1c05942]
[Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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The annotinolides are one of the
most recent additions to the Lycopodium family of
alkaloids, with its members possessing
challenging, caged structures that include a [3.2.1]-bicyclic core
bearing six contiguous stereocenters, including four that are fully
substituted. Herein, we document a concise and stereoselective route
that achieves the first total syntheses of three of its members: annotinolides
C, D, and E. Key operations include a gold(I)-catalyzed Conia-ene
reaction that fashions much of the main core in a single operation,
as well as a number of other challenging and chemoselective transformations
to generate the remaining elements. Moreover, efforts utilizing the
natural products themselves, seeking adjustments in their oxidation
states and the rearrangement of individual ring systems, shed light
on their potential biogenesis with some outcomes counter to those
originally proposed. Finally, formal enantioenriched syntheses of
the target molecules are also presented.
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