Diels–Alder reaction between 1,3,3-trisubstituted-2-vinylcyclohexenes and quinones under exceptionally mild conditions: a concise entry to the cassane-type furanoditerpenoid skeleton

Extremely mild (no metal Lewis acid catalyst, ambient temperature) and experimentally simple (no high-pressure apparatus needed) conditions were established for the Diels–Alder reaction between sterically demanding 1,3,3-trisubstituted-2-vinylcyclohexenes and non-symmetrically substituted quinones. This allowed for the successful implementation of a highly convergent strategy to the cassane-type furanoditerpenoid skeleton.