Synthesis and redox behavior of ene–diyne scaffolds that bear ferrocenes at the periphery

The ene–diyne systems 1 and 2 possessing ferrocenyl groups at the periphery were prepared by the simple one-pot Sonogashira–Hagihara coupling reaction of ethynylferrocene with 9-dibromomethylene-9H-fluorene (4) and 9,10-bis(dibromomethylene)-9,10-dihydroanthracene (5). The novel ferrocene-substituted ene–diyne compounds exhibited amphoteric redox behavior with a reversible one-stage electrochemical oxidation upon cyclic voltammetry.