Preparation, X-ray structure, and reactivity of 2-iodylpyridines: recyclable hypervalent iodine(V) reagents.

2-Iodylpyridine and four examples of 3-alkoxy-2-iodylpyridines were prepared by oxidation of the respective 2-iodopyridines with 3,3-dimethyldioxirane. Structures of 2-iodylpyridine, 2-iodyl-3-isopropoxypyridine, and 2-iodyl-3-propoxypyridine were established by single-crystal X-ray diffraction analysis. 2-Iodyl-3-propoxypyridine has moderate solubility in organic solvents (e.g., 1.1 mg/mL in acetonitrile) and can be used as a recyclable reagent for oxidation of sulfides and alcohols. The reduced form of this reagent, 2-iodo-3-propoxypyridine, can be effectively separated from the reaction mixture by treatment with diluted sulfuric acid and recovered from the acidic aqueous solution by adding aqueous sodium hydroxide.