Markovnikov versus anti‐Markovnikov Hydrophosphination: Divergent Reactivity Using an Iron(II) β‐Diketiminate Pre‐Catalyst

Abstract The ability to tune between different regioselectivities using a common pre‐catalyst is an unusual yet highly desirable process. Here, we report the use of an iron(II) pre‐catalyst that can be used to synthesize vinyl phosphines in a Markovnikov‐selective manner in benzene, whereas a simple change to dichloromethane as the reaction solvent leads to the Z ‐selective anti ‐Markovnikov product. Preliminary mechanistic studies are reported that suggest Markovnikov selectivity is a radical‐mediated process, whereas the anti ‐Markovnikov selectivity is not radical in nature but is due to a change in oxidation state.