Total Syntheses of (±)‐Dracocephalone A and (±)‐Dracocequinones A and B

Described herein are the first total syntheses of (±)‐dracocephalone A (1) and (±)‐dracocequinones A (4) and B (5). The synthesis was initially envisioned as proceeding through an intramolecular isobenzofuran Diels–Alder reaction, a strategy that eventually evolved into a Lewis acid‐promoted spirocy...

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Veröffentlicht in:Angewandte Chemie 2022-11, Vol.134 (46), p.n/a
Hauptverfasser: Hwang, Taehwan, Tuccinardi, Joseph P., Beard, Alexandra A., Jackson, Amy C., Jung, Min J., Wood, John L.
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Sprache:eng
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Zusammenfassung:Described herein are the first total syntheses of (±)‐dracocephalone A (1) and (±)‐dracocequinones A (4) and B (5). The synthesis was initially envisioned as proceeding through an intramolecular isobenzofuran Diels–Alder reaction, a strategy that eventually evolved into a Lewis acid‐promoted spirocyclization. This highly diastereoselective transformation set the stage for trans‐decalin formation and a late‐stage Suárez oxidation that produced a [3.2.1] oxabicycle suited for conversion to 1. Brønsted acid‐mediated aromatization, followed by a series of carefully choreographed oxidations, allowed for rearrangement to a [2.2.2] oxabicycle poised for conversion to 4 and 5. Described herein are the first total syntheses of (±)‐dracocephalone A (1) and (±)‐dracocequinones A (4) and B (5). An initially‐envisioned intramolecular isobenzofuran Diels–Alder strategy guided the evolution of a Lewis acid‐promoted spirocyclization approach that allowed for access to the carbocyclic core of 1. Further advancement by a series of carefully choreographed oxidations and rearrangements allowed for conversion to 1, 4, and 5.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.202210821