Ferrocenyl substituted chlorostilbenes and butadienes

Abstract

The readily accessible α-chlorophosphonates (OCH₂CMe₂CH₂O)P(O)CH(Cl)---C₆H₄-4-R [1: R=Me (a), OMe (b), Cl (c), H (d)] react with ferrocenecarboxaldehyde in the presence of NaH [Horner-Wadsworth-Emmons reaction] to give good yields of ferrocenyl substituted chlorostilbenes. The novel bis ferrocenyl butadiene C₅H₅FeC₅H₄---CH=CH---C(CN)CHC₅H₄FeC₅H₅ (9) as well as the ferrocenyl 2-cyano-1,3-butadienes 4-R---C₆H₄---CH=CH---C(CN)=CHC₅H₄FeC₅H₅ [R=Me (10a), OMe (10b), Cl (10c)] have been obtained by using the new allylphosphonate (OCH₂CMe₂CH₂O)P(O)CH₂C(CN)=CHC₅H₄FeC₅H₅ (8); the latter compound was prepared in good yields by the reaction of the Baylis-Hillman adduct, C₅H₅FeC₅H₄CH(OH)C(CN)=CH₂ (7), with the chlorophosphite (OCH₂CMe₂CH₂O)PCl. The electrochemical behavior of the ferrocenyl compounds thus synthesized has been studied; two reversible one-electron processes are observed in the case of compound 9 suggesting a cooperative interaction between the two ferrocenyl residues.