A Stereoselective Photoinduced Cycloisomerization Inspired by Ophiobolin A

A concise, modular, and stereoselective synthetic entry point to the 5-8-5 carbocyclic core of the ophiobolins is described. This strategy exploits the chiral tertiary alcohol of ophiobolin A to guide assmebly of the 5-8-5 scaffold in a single step via photoinitiated isomerization. Mechanistic insights into the origin of stereocontrol in this reaction are described, as are efforts to elaborate the resultant 5-8-5 polycycle to the pharmacophore of ophiobolin A.