A stereoselective total synthesis of the novel triquinane sesquiterpene cucumin E

A total synthesis of cucumin E, a recently isolated triquinane natural product with a new carbon framework, has been achieved. The key step is the flash vacuum pyrolysis (FVP)-induced cyclobutane fragmentation in a readily available pentacyclic caged dione to deliver the triquinane skeleton with functionalization in all the three five-membered rings suitable for further elaboration to the natural product.