Double Diastereoselection in Intramolecular Photocycloadditions: A Radical Rearrangement Approach to the Total Synthesis of the Spirovetivane Phytoalexin (±)-Lubiminol

The highly stereoselective total synthesis of the phytoalexin (±)-lubiminol ( 1 ) has been accomplished. The synthesis relies on three pivotal transformations: (1) a conjugate addition−cyclization reaction to prepare a highly functionalized 2-carbomethoxycyclopentenone as a photocycloaddition substrate, (2) a double diastereoselective intramolecular photocycloaddition for a stereoselective intramolecular photoaddition reaction which establishes the central quaternary spirocenter, and (3) the transformation of the photoadduct into the required spiro[5.4]decane through a radical fragmentation−rearrangement reaction.