Tuning Diketodioxinone Reactivity: Biomimetic Synthesis of the Resorcylate Antibiotic Fungal Metabolites <i>ent</i>-W1278A, -B, and -C, Using Iterative Aromatization Reactions

Abstract

The onset temperature of the retro-Diels-Alder reactions of diketo-1,3-dioxin-2-ones to generate alpha,gamma,epsilon-triketo-ketenes was found to be significantly reduced with 2-phenyl substitution. These ketenes, generated at 78 degrees C, were trapped with alcohols to provide resorcylate esters following aromatization by sequential reaction with cesium acetate and trifluoroacetic acid. The methodology was applied iteratively to the total synthesis of the resorcylate antibiotics W1278A, -B, and -C. It is noteworthy that in this process the linking of the monomer units occurs during construction of the aromatic ring.