A Stereoselective Photoinduced Cycloisomerization Inspired by Ophiobolin A.

A stereoselective synthetic entry point to the 5-8-5 carbocyclic core of the ophiobolins was developed. This strategy exploits the chiral tertiary alcohol of ophiobolin A to guide assmebly of the 5-8-5 scaffold in a single step via a photoinitiated cycloisomerization. Mechanistic insights into the origin of stereocontrol in this reaction are described, as are efforts to elaborate the resultant fused 5-8-5 ring system to the pharmacophore of ophiobolin A.