After reaction of ICl and Ag 2 SO 4 in sulfuric acid and separation of resulting AgCl a stable solution is formed, containing very active forms of electrophilic iodine. This solution has a powerful iodination ability with respect to aromatic compounds. Deactivated arenes are iodinated easily and in mild conditions by action of this new reagent in generally good yields of the iodoarenes.Iodoarenes are valuable, versatile synthetic intermediates and have found wide applications in medicine and biochemistry. But the electrophilic nature of iodine is weaker than bromine and chlorine. For this and other reasons there are few methods for direct iodination of deactivated aromatics known. 1 Some arenes having electron-withdrawing substituents can be iodinated by the I 2 /Ag 2 SO 4 system in sulfuric acid. Under these conditions nitrobenzene (1a) is transformed into 3-iodonitrobenzene (2a) at 100 °C within 2-3 hours. 2 The use of iodine in 20% fuming sulfuric acid (oleum) for iodination of a range of aromatic nitro compounds was described. 3 In these conditions nitrobenzene (1a) can be iodinated to 3-iodonitrobenzene (2a) at room temperature and within 20 hours with 52% yield. Specific iodination of some deactivated arenes was achieved by using iodine with fluorine as the oxidant. 4 Probably nowadays the most active iodination agent is N-iodosuccinimide in CF 3 SO 3 H. 5 Deactivated arenes were found to react easily with this reagent giving iodoarenes with good yields. So, for example, nitrobenzene (1a) gives iodonitrobenzene 2a (86%) within two hours at room temperature. 5

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Superactive Iodination Reagent on a Base of Iodine Chloride and Silver Sulfate.-A superactive iodination reagent is obtained in sulfuric acid solution from iodine chloride and silver sulfate. This solution allows the direct iodination of electron poor arenes (I). -(CHAIKOVSKI, VITOLD K.; KHARLOVA, TATJANA S.; FILIMONOV, VICTOR D.; SARYUCHEVA, TAMARA A.; Synthesis (1999) 5, 748-750; Dep. Chem., Tomsk Polytech. Univ., Tomsk 634004, Russia; EN)