Regiocontrol switching in CC bond formation during decomplexation of a tricarbonyl(η4-cyclohexadiene)iron complex

Abstract A study has been made of additions of nucleophiles to the tricarbonyl( η 4 -cyclohexadiene)iron complex 1 and subsequently reaction of the resulting anions with several electrophiles in the presence of added ligands. Carbonyl insertion to form a functionalised cyclohexene ring is assisted by the addition of phosphines. Depending on the electrophilic reagent, an unusual phosphine-controlled switch in regiochemistry (PhCH 2 Br), and interruption of the process prior to loss of the metal (CH 2 =CHCH 2 Br), have been observed.