Selective Generation of Mono- and 1,1′-Dilithioferrocenes by Lithium-Tellurium Exchange. Efficient Routes to Mono- and Symmetrical and Unsymmetrical 1,1′-Di-substituted Ferrocenes

The generation of mono- and I,1'-dilithioferrocenes by transmetalation of butyl ferrocenyl tellurides 3 and 5 is reported; these intermediates and the mono-transmetalation species from 5 provide new alternative and improved routes for the preparation of pure substituted ferrocenes 4, 6, 7, and 8.