An oxidative CÀ N bond cleavage reaction of substituted cyclic sulfonamides that proceeds via oxidation of bromide ion in hydrogen bromide solution was developed to furnish N-sulfonamideprotected acyclic amino ketones in high yields. The subsequent α-amination of the amino ketones via the oxidation of iodide in tetrabutylammonium iodide provided 2-acyl cyclic sulfonamides in good yields. The combination of these transformations involving the oxidation of halides resulted in a formal ring contraction of substituted cyclic amides.
We developed a method for the preparation of (diacetoxyiodo)‐2‐(N‐alkylamido)benzene as an aniline‐type hypervalent iodine(III). We also achieved direct cyclizations via C−H bond abstraction, such as the Hofmann‐Löffler‐Freytag reaction, a direct amination, and a direct lactonization, using the aniline‐type hypervalent iodine(III) to obtain corresponding products in high yields.
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