Stereoselective synthesis of the spirocyclic core of 13-desmethyl spirolide C using an aza-Claisen rearrangement and an exo-selective Diels–Alder cycloaddition

This work details a novel approach to access the [7,6]-spirocyclic fragment of 13-desmethyl spirolide C. A more efficient synthesis of the key lactam dienophile is reported, and a comprehensive investigation of the Diels-Alder reaction is included.