Migration Reaction of a Hypervalent Fragment: Base-Induced Migration of a Phosphorane Fragment from Iron to the Cyclopentadienyl Ring in Cp(CO)2Fe{P(OC6H4Y)(OC6H4Z)} (Y, Z = NMe, NH, O)
摘要:
Iron phosphorane complexes, Cp(CO)(2)Fe{P(OC6H4Y)(OC(6)H(4)Z)} (Y,Z=NMe,O), react with lithium diisopropylamide (LDA) and then MeI to give {eta(5)-C5H4P(OC6H4Y)(OC(6)H(4)Z)}(CO)(2)FeMe, showing the first example of migration of a hypervalent phosphorus fragment. The structure of one of the migration products, {eta(5)-C5H4P(OC6H4NMe)(2)}(CO)(2)FeCH2Ph,was determined by X-ray analysis. Spectroscopic monitoring of the migration reaction suggests that the reaction is initiated by a proton abstraction on the Cp ring by LDA, followed by migration of the phosphorane fragment to the Cp ring to give {eta(5)-C5H4P(OC6H4Y)(OC(6)H(4)Z)}(CO)(2)Fe-, which is converted into {eta(5)-C5H4P(OC6H4Y)(OC(6)H(4)Z)}(CO)(2)FeR by the treatment of alkyl halide. The reaction of Cp(CO)(2)Fe{P(OC6H4NH)(2)} containing two NH groups with LDA proceeds first with NH proton abstraction to give Cp(CO)(2)Fe{P(OC6H4NH)(OC6H4N-)} and then with CP proton abstraction followed by phosphorane migration to give {eta(5)-C5H4P(OC6H4NH)(OC6H4N-)}(CO)(2)Fe-. The addition of MeI finally led to the isolation of {eta(5)-C5H4P(OC6H4NH)(OC6H4NH)}(CO)(2)FeMe and {eta(5)-C5H4P(OC6H4NH)(OC6H4NMe)}(CO)(2)FeMe.