Synthesis of unsymmetrical 1,1′-disubstituted ferrocenes. Formation of ferrocenophanes via intramolecular cycloaddition

Unsymmetrical 1,1′-disubstituted ferrocenes bearing appropriate substituents for intramolecular cycloadditions were synthesized conveniently starting from 1,1′-ferrocenedicarbaldehyde. Ferrocenenitrone derivatives reacted in an intramolecular regioselective manner affording ferrocenophanes.