Frontispiece: Boosting Molecular Complexity with O2: Iron‐Catalysed Oxygenation of 1‐Arylisochromans through Dehydrogenation, Csp3−O Bond Cleavage and Hydrogenolysis

1‐Arylisochromans were easily converted in valuable 2‐(hydroxyethyl)benzophenones by means of a selective Csp3−O aerobic cleavage promoted by a FeII–pyridyl(bis‐imidazolidine) catalyst. The reaction proceeded with high selectivity and impressive functional group tolerance at mild and environmentally friendly conditions. From a mechanistic perspective, the iron catalyst promotes the dehydrogenative oxygenation of the 1‐arylisochroman releasing a structurally characterized peroxide intermediate and H2 gas. The formation of the 2‐(hydroxyethyl)benzophenones is postulated to occur through Csp3−O bond cleavage of the peroxide at the iron center followed by the hydrogenolysis of the Fe−O bonds with the released H2. Interestingly, electron‐rich 1‐arylisochromans were also transformed in benzoates by means of a radical auto‐oxidative Csp3−Csp2 cleavage, further highlighting the synthetic potential that can be gained by aerobic cleavages. For more information see the Full Paper by J. Xiao et al. on page 4345 ff.