3 - (Diacetoxyiodo)benzene

Abstract

This chapter discusses (Diacetoxyiodo)benzene (DIB), which is one of the most popular reagents of hypervalent iodine, used in 1939 in acetoxylations of ethylenic double bonds. Apart from oxidations of a great diversity, DIB has found applications in several other useful transformations, including α-functionalization of carbonyl compounds, carbon–carbon bond forming reactions, rearrangements, cyclizations, and so on. It is also a good starting material for the preparation of other hypervalent iodine compounds. In several instances DIB is used in combination with other reagents. Acetophenones, aliphatic and cyclic ketones were α-acetoxylated by DIB in acetic acid–acetic anhydride, in the presence of sulfuric acid, in moderate yield; some β-diketones were similarly acetoxylated at the methylene carbon. The more reactive trimethylsilyl ethers reacted at room temperature without acid catalysis, with retention of their silyl group; the products were generated either from substitution of the vinylic hydrogen or from bis acetoxylation of the double bond. Enolizable ketones were converted directly into their α-hydroxy dimethyl acetals upon reaction with DIB and methanolic potassium hydroxide at room temperature. If, during work up, there was acid treatment, then α-hydroxyketones were directly obtained.