Hypervalent Iodine for Environmentally Benign Catalytic Oxidation

2-Iodosobenzoic acid (IBA) is known as a byproduct of IBX oxidation and is utilized not only as an oxidant of sulfide¹⁾ but also as a catalyst for oxidation reactions.²⁾ For instance, in the presence of catalytic amount of IBA with oxygen or DMSO, fluorene is oxidized to afford fluorenone in high yields. This condition is also applicable to the oxidation of benzyl alcohols and conversion of indoles to isatins. Furthermore, recovered IBA after the reaction can be regenerated and reused for next reaction without any loss in its activity.