Cytochalasan synthesis: total synthesis of cytochalasin H

Cytochalasin H (2) has been synthesized using an intramolecular Diels–Alder reaction to form the [11]Cytochalasan skeleton. This was highly stereoselective and gave adduct (49) with the correct configurations at all chiral centres. The later stages of the synthesis involved stereoselective cyclohexene epoxidation–epoxide rearrangement, introduction of the C-19–C-20 double bond, and stereoselective reduction of the C-21 ketone.