Unified Divergent Total Syntheses of Illudalane Sesquiterpenes from Granulolactone via a One-Pot Diels–Alder/Oxidative Aromatization

We describe an efficient and unified strategy for the total synthesis of seven illudalane sesquiterpenes starting from the readily accessible precursor granulolactone. The route features a Julia olefination and a gram-scale, one-pot Diels-Alder/oxidative aromatization sequence that rapidly forges the densely substituted illudalane core. Use of granulolactone as a common intermediate enables a divergent late-stage branching strategy, allowing rapid access to multiple natural products from a single scaffold. This concise approach highlights the power of divergence-oriented synthesis for the efficient preparation of structurally diverse illudalane frameworks and provides a platform for future analogue development.