A concise total synthesis of unprecedented tetranorsesquiterpenoids applanatumol Z5

A concise total synthesis of tetranorsesquiterpenoids applanatumol Z5 (3), possessing unique 6/5/5 ring system was disclosed with 7-step in 5-pot from commercially available starting materials. The key elements of the synthesis included an unexpected intramolecular dithiolane with alcohol oxidative coupling/deprotection sequence to create the unsaturated lactone as dienophile and a regioselective Diels-Alder reaction to assemble the 6/5/5 tricyclic scaffold including two vicinal quaternary carbon stereocenters. Late stage the diastereo- and regioselective carbonyl reduction led to achieve the total synthesis of (±) applanatumol Z5 (3).