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

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.