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...
Gespeichert in:
Veröffentlicht in: | Angewandte Chemie 2022-11, Vol.134 (46), p.n/a |
---|---|
Hauptverfasser: | , , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
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 |