One-pot Mukaiyama hydration paired with Fe(II) β-scission promotes the deconstructive manipulation of substrates containing isopropenyl groups. The ozone-free reductive dealkenylation protocol smoothly allows for the use of O2 instead of O3 for the peroxide formation step. Such a transformation may be highly enabling in multistep synthesis, such as shearilicine, wherein routes proceed via ozone sensitive substrates.