Enantioselective and Collective Total Syntheses of Xanthanolides

An enantioselective synthesis of (+)‐8‐epi‐xanthatin hinging on a chiral phosphoric acid catalyzed tandem allylboration/lactonization reaction is reported. With (+)‐8‐epi‐xanthatin as the precursor, the collective synthesis of a series of synthetically challenging xanthanolides was also accomplished. Among them, xanthipungolide, one of the most complex xanthanolide monomers, was accessed through a bioinspired tandem double‐bond isomerization/6π electronic cyclization/intramolecular Diels–Alder reaction, and pungiolides A, B, D, E, and L–N, a group of xanthanolide dimers, were assembled through a bioinspired Diels–Alder dimerization followed by late‐stage diversification. Vielfalt ist Trumpf: Die enantioselektive Synthese von (+)‐8‐epi‐Xanthatin aus leicht erhältlichen Fragmenten wurde in sieben Stufen (längste lineare Sequenz) und 15 % Gesamtausbeute vollendet. Weitere 1–3 Stufen werden für die kollektive Totalsynthese verschiedener anspruchsvoller Xanthanolid‐Monomere und ‐Dimere basierend auf einer Serie bioinspirierter Transformationen benötigt.