Transition-metal mediated asymmetric synthesis. Part 5. Alternative methods for the formation of tricarbonyl(η5-cyclohexadienyl)iron(1+) salts

Abstract

The influence of substituents on the preparation of tricarbonyl(η⁵-cyclohexadienyl) iron(1+) salts by oxidation using thallium(III) tris(trifluoroacetate) and by hydride abstraction using 2,3-dichloro-5,6-dicyano-1,4- benzoquinone–tetrafluoroboric acid has been examined. Hydride abstraction by thallium oxidation is superior to conventional methods and offers complementary regiocontrol in some cases. An example of hydride abstraction from a blocked tricarbonyl(η⁴-cyclohexadiene) iron complex is described.