THE KINETICS AND MECHANISM OF DIENE EXCHANGE IN (η4-ENONE)Fe(CO)2L COMPLEXES (L = PHOSPHINE, PHOSPHITE)

Article abstract of DOI:10.1016/0022-328X(84)80113-8

Kinetic data for the exchange of 1,3-cyclohexadiene with (η⁴-benzylideneacetone)Fe(CO)2L complexes (L = CO, PPh3-xMex (x = 0-2) or P(OPh)3) to give (η⁴-1,3-cyclohexadiene)Fe(CO)2L derivatives indicate a mechanism involving stepwise competing D and I_d opening of the ketonic M-CO ?-bond.Rates increase in the order CO>>PPh3<*>P(OPh)3>PPh2Me>>PPhMe2, and both steric and electronic factors appear to be important. (η⁴-1,3-cyclohexadiene)Fe(CO)2L complexes of potential use in enantioselective synthesis (L = (+)-Ph2P(menthyl) or (+)-Ph2PCH2CH(Me)Et) may be preparedvia their (η⁴-benzylideneacetone)Fe(CO)2L complexes.