One-step synthesis of aryl-capped vinylferrocenes from ferrocene and aryl-substituted oxiranes

Ferrocene reacts in methanesulfonic acid with aryl- and diaryloxiranes to afford (2-arylvinyl)- and (2,2-diarylvinyl)ferrocenes, respectively. The reaction with aryloxiranes is highly stereoselective and gives only the (E)-isomers. The reaction presumably proceeds via fast isomerisation of the protonated oxirane to the protonated carbonyl compound, which attacks ferrocene.