Stereoselective synthesis of the rocaglamide skeleton via a silyl vinylketene formation/[4 + 1] annulation sequence.

The tricyclic core of the cyclopentabenzofurans has been prepared in an efficient and stereoselective manner utilizing an intramolecular silyl vinylketene formation/[4 + 1] annulation sequence. This novel approach affords the ABC ring system where the adjacent phenyl and aryl substituents of the C ring have the required cis relationship.