Dess-Martin Periodinane, a hypervalent iodine compound, offers selective and very mild oxidation of alcohols to aldehydes or ketones. The oxidation is performed in dichloromethane or chloroform at room temperature, and is usually complete within 0.5 – 2 hours. It has the Synonyms: 1,2-Benziodoxol-3(1H)-one, 1,1,1-tris(acetyloxy)-1,1-dihydro-, and it is mostly known as DMP. It is a kind of white crystalline powder with Molecular Formula: C13H13IO8 and Molecular Weight: 424.14, the CAS Registry Number is 87413-09-0.
Dess-Martin periodinane is commercially available and decomposes only slowly. But Dess-Martin periodinane is heat and shock-sensitive, and shows an exotherm when heated >130 C. 2-Iodoxybenzoic acid (IBX), the impact-sensitive intermediate in the synthesis of the Dess-Martin periodinane, is available in a DMSO solution and is also used as an oxidizing agent.
Partial hydrolysis of Dess-Martin periodinane or incomplete acetylation gives a more effective oxidant, explaining why impure samples of this compound in many cases provide better results than the pure reagent. When reliable and convenient rate enhancement is desired, pure Dess-Martin periodinane may be decomposed with an equivalent of water immediately before or during its use.
Dess-Martin periodinane is mainly used as an oxidant for complex, sensitive and multifunctional alcohols. One of the reasons for its effectiveness is its high selectivity towards complexation of the hydroxylic group, which allows alcohols to rapidly perform ligand exchange; the first step in the oxidation reaction.
Proton NMR has indicated that using one equivalent of alcohol forms the intermediate diacetoxyalkoxyperiodinane. The acetate then acts as a base to deprotonate the α-H from the alcohol to afford the carbonyl compound, iodinane, and acetic acid.When a diol or more than one equivalent of alcohol is used, acetoxydialkoxyperiodinane is formed instead. Due to the labile nature of this particular periodinane, oxidation occurs much faster.
Using the standard Dess-Martin periodinane conditions, alcohols can be oxidized to aldehydes/ketones without affecting furan rings, sulfides, vinyl ethers, and secondary amides. Allylic alcohols are easily oxidized using this chemical, which are typically difficult to convert to their respective carbonyls using the typical oxidants.
Difluoro and monofluoro alcohols are more difficult to oxidize. Swern oxidation has been used, but a large excess of the oxidant had to be employed, and in some cases did not give reproducible results. Linderman and Graves found Dess-Martin periodinane(CAS NO:87413-09-0) was partially successful, but side reactions occurred. Using the modified DM oxidant shown below, produced the wanted carbonyl in high yields. The reason Linderman and Graves chose tert-butyl alcohol as a ligand instead of acetate was due to its bulk and nonoxidizable characteristics. This was to minimize the unwanted byproduct acetic acid formed.
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