Natural Products Synthesis by Retro Diels-Alder Reactions IV:¹Total Synthesis of (±)-Invictolide and (±)-6-Epiinvictolide

Abstract

Efficient total syntheses of (±)-invictolide 8 and its 6-epimer 9 are described. Starting from enone 4, tandem conjugate addition-enolate trapping with aldehydes, followed by another 1,4-addition and retro Diels-Alder ŕeaction, afforded key intermediates 12a and 12b which were converted into precursors 15a and 15b through hydrogenation and Baeyer-Villiger oxidation.