Total Synthesis of (+)-Aureol

We report a full account on the development of a unique cationic polyene cyclization for the total synthesis of the tetracyclic meroterpenoid (−)‐cyclosmenospongine. A highly convergent three‐component coupling strategy enabled rapid access to individual cyclization precursors that were tested for their reactivity. The successful transformation generates three rings and sets four consecutive stereocenters in a single operation proceeding in a highly efficient manner to give exclusively the trans‐decalin framework. In addition, we found that the enol ether geometry and the relative configuration of C3 and C8 are crucial for the success of the polyene cyclization.

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“… a) Representative members of tetracyclic meroterpenoid natural products and b) their proposed biosynthesis (adapted from George and Faulkner) …”

Section: Introductionmentioning

confidence: 99%

Evolution of a Polyene Cyclization Cascade for the Total Synthesis of (−)‐Cyclosmenospongine

Speck

Magauer

2016

Chemistry A European J

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“…There have been reports on the total synthesis of natural (+)-2, [8,9] unnatural (-)-2 and (-)-3, [10] and natural (+)-4. There have been reports on the total synthesis of natural (+)-2, [8,9] unnatural (-)-2 and (-)-3, [10] and natural (+)-4.…”

Section: Introductionmentioning

confidence: 99%

Total Synthesis of (+)‐Strongylin A, a Rearranged Sesquiterpenoid Hydroquinone from a Marine Sponge

2013

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A biologically attractive and structurally unique marine natural product, (+)‐strongylin A (1), was synthesized for the first time by starting from a known trans‐decalone derivative (19 % overall yield in 11 steps). The synthetic method involved the following key steps: (i) stereocontrolled hydrogenation of an exo‐olefinic decalin to install the C8 stereogenic centre present in the required decalin segment; (ii) coupling of the decalin segment with an aromatic moiety to assemble the desired carbon skeleton; and (iii) sequential BF3·Et2O‐induced dehydroxylation/rearrangement/cyclization of a decalin tertiary alcohol to directly produce target compound 1. This total synthesis has established the absolute configuration of the natural product.

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“…This substrate is already poised for a polyene cyclization cascade, which only has to be triggered via activation of the epoxide. After the decalin moiety has formed, two sigmatropic, stereospecific [1,2]-shifts of intermediate 170 provide the tertiary carbocation 171 , which could be trapped by the phenolic alcohol to give stachyflin ( 156 ) [143]. …”

Section: Reviewmentioning

confidence: 99%

The chemistry of isoindole natural products

Speck¹,

Magauer²

2013

Beilstein J. Org. Chem.

316

163

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SummaryThis review highlights the chemical and biological aspects of natural products containing an oxidized or reduced isoindole skeleton. This motif is found in its intact or modified form in indolocarbazoles, macrocyclic polyketides (cytochalasan alkaloids), the aporhoeadane alkaloids, meroterpenoids from Stachybotrys species and anthraquinone-type alkaloids. Concerning their biological activity, molecular structure and synthesis, we have limited this review to the most inspiring examples. Within different congeners, we have selected a few members and discussed the synthetic routes in more detail. The putative biosynthetic pathways of the presented isoindole alkaloids are described as well.

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Total Synthesis of (+)-Aureol

Abstract: A total synthesis of the marine sponge meroterpenoid (+)-aureol has been achieved in 12 steps (6% overall yield) from (+)-sclareolide. Key steps of the synthesis include a biosynthetically inspired sequence of 1,2-hydride and methyl shifts, and a biomimetic cycloetherification reaction.

Cited by 38 publications

References 25 publications

Evolution of a Polyene Cyclization Cascade for the Total Synthesis of (−)‐Cyclosmenospongine

Evolution of a Polyene Cyclization Cascade for the Total Synthesis of (−)‐Cyclosmenospongine

Total Synthesis of (+)‐Strongylin A, a Rearranged Sesquiterpenoid Hydroquinone from a Marine Sponge

The chemistry of isoindole natural products

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