Oxidations with Hypervalent Iodine Compounds
Inorganic iodide (I-) and organoiodine compounds form a series of oxides by consecutive oxidations of the iodine lone pairs.
Several of these iodine oxides, suitably modified to improve solubility, reactivity, and/or accessibility have useful properties as oxidizing agents. Some chlorine and bromine analogs are also useful.
Oxidation with Periodate
NaIO4 (I+7) is a mild oxidant, whose most important use is the oxidative cleavage of vicinal glycols. Archazolid A (Part 1): Menche, D.; Hassfels, J.; Li, J.; Mayer, K.; Rudolph, S. J. Org. Chem. 2009, 74, 7220. DOI
Periodate also functions as a reoxidant for OsO4, allowing one-pot cleavage of alkenes to aldehydes using a catalytic amount of osmium (the Lemieux-Johnson oxidation). Hemibrevetoxin B: Zakarian, A.; Batch, A.; Holton, R. A.. J. Am. Chem. Soc. 2003, 125, 7822-7823. DOI
Periodate is also useful as a reoxidant for Ruthenium oxide oxidations, and for the mild and selective oxidation of sulfides and selenides to sulfoxides and selenoxides.
Oxidation with o-Iodoxybenzoic Acid (IBX)
ortho-Iodoxybenzoic acid can be prepared by the oxidation of ortho-iodobenzoic acid. It forms a cyclic "hemiacetal"-like structure. Although it is a powerful oxidant, its poor solubility properties limit its applicability, and result in relatively harsh reaction conditions being required.
Oxidation of alcohols and ketones to enones: Nicolaou, K. C.; Zhong, Y.-L.; Baran, P. J. Am. Chem. Soc. 2000, 122, 7596
Oxidation of phenols to o-quinones: Dichroanone McFadden, R. M.; Stoltz, B. M. J. Am. Chem. Soc. 2006, 128, 7738 DOI
Oxidation of aromatic side chains: Nicolaou, K. C.; Baran, P.; Zhong, Y.-L. J. Am. Chem. Soc. 2000, 122, 7596
Miscellaneous Oxidations: Nicolaou, K. C.; Casey, J. N. M.; Montagnon, T. J. Am. Chem. Soc. 2004, 126, 5192
Oxidation of Alcohols with Dess-Martin Periodinane
The Dess-Martin periodinane (Martin, J. C.; Dess, D. B. J. Org. Chem., 1983, 48, 4155), closely related to IBX, is prepared similarly, except under dehydrating conditions with acetic anhydride. It needs to be treated with care since it is shock sensitive and has the potential for high energy decomposition.
DMP has with much better solubility properties than IBX, and is currently the reagent of choice for the mild and convenient oxidation of alcohols to aldehydes and ketones on a small scale, having displaced most transition metal oxidants where cost (and the hazard of working with a shock-sensitive compound) is not an issue. It is competing well with Moffat-Swern DMSO-based oxidations, but does show some tendency to cleave glycols and α-hydroxy ketones, so DMSO oxidations are usually the preferred method for oxidations of glycols to α-hydroxyketones or 1,2-diketones.
Evans J. Am. Chem. Soc., 1990, 112, 7007.
