Electrophilic substitutions on some ferrocenyl analgues of chalcones an unusual reaction caused by the high stability of the α-ferrocenylmethyl carbenium ion

Friedel—Crafts acetylation of 5-ferrocenyl-1-phenyl-2,4-pentadie-1-one and 1-ferrocenyl-5-phenyl-1,4-pentadien-3-one has been acomplished. It was found that acetylation takes place on the unsubstituted cyclopentadienyl ring of ferrocene as well as on the double bond of chalcones. In the light of these results the Friedel—Crafts acetylation of 3-ferrocenyl-1-phenyl-2-propen-1-one was reinvestigated and the structures of some drivatives, described earlier, were corrected. The mechanism of the acetylation is discussed briefly.Friedel—Craft alkylation and electrophilic bromination of 3-ferrocenyl-1-phenyl-2-propen-1-one have also been attempted.