| Abstract: | The asymmetric total synthesis of farnesin, a rearranged ent‐kaurenoid, was achieved through a convergent approach involving photo‐Nazarov and intramolecular aldol cyclizations to build the syn‐syn‐syn hydrofluorenol ABC ring system and bicyclo3.2.1]octane CD ring system in the first application of a UV‐light‐induced excited‐state Nazarov cyclization of a non‐aromatic dicyclic divinyl ketone in a total synthesis. Unlike the conventional acid‐promoted ground‐state Nazarov reaction, the excited‐state Nazarov reaction enables stereospecific formation of the highly strained syn‐syn‐syn‐fused hydrofluorenone scaffold through a disrotatory cyclization. |
