Stereoselective synthesis of tetrasubstituted olefins through a halogen-induced 1,2-silyl migration.

Migrating through Si valley: The highly stereoselective formation of α-silyl-β- haloenones by way of silicon group migration is described. Electrophilic activation of the alkyne by N-halosuccinimides induced an anti-selective migration to give highly substituted enones (see scheme). These enone products can be readily converted to the all-carbon tetrasubstituted alkenes while maintaining their geometry.