Ferrocene compounds: XX. Synthesis and reactions of some ferrocene fulvenes

Reaction of several aroylferrocenes( 1) with cyclopentadienide (from cyclopentadiene and sodium in ethanol) has given 6-aryl-6-ferrocenylfulvenes ( 2) in 53–69% yields. Similarly, starting from 1,1′-diaroylferrocenes ( 5), the corresponding bisfulvenes 6 have been obtained in ca. 70% yields. Upon standing, in solution or as solids the fulvenes 2 or 6 give equilibrated mixtures with the corresponding dimers 3 and 7 and oligomers 8. Addition of acrylonitrile to the ferrocene fulvenes gave the endo-isomers 4 in 49–57% yields and mixtures of endo- and exo-bisadducts 10 in 56–75% yields.