A new cyclic nitrone spin trap,[4-(3′, 3′-dibutyl-2′-oxy-3′ H-isoindol-5′-yloxy) butyl] triphenylphosphonium bromide (MitoSpin), bearing a lipophilic cation has been prepared by a route that involves a novel Parham-type lithiation–cyclization of an isocyanate to give the isoindolinone core. MitoSpin accumulates in a membrane potential dependent way in energized mitochondria and its oxidation could potentially be used in the study of ...