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

Abstract

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 transdecalin 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. Chagas disease (CD) is transmitted by the protozoan[*] T.