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Catalytic Hypervalent Iodine Catalysts

Mechanism + Description

The activation of the aryl iodide catalyst by oxidation ‘in situ‘ by Oxone, followed by the expected oxidation mechanism for IBX/ Dess-Martin reagents. The reduced catalyst is re-oxidized to the high valent active form and the aldehyde product is further oxidized via the hydrate to the acid.

General comments

A number of examples have been published using terminal oxidants (mainly Oxone) to generate hypervalent iodine compounds in situ. These react very much as stoichiometric IBX/Dess Martin reagents. The oxidation of the primary alcohol to the aldehyde occurs, followed by a second oxidation of the aldehyde hydrate. These catalytic methods avoid having to use isolated unstable/explosive hypervalent iodine reagents.

Key references

Yakura, T.; Yamada, A.; Noda, N.; Fujiwara, T.; Nambu, H. A 2-Iodobenzamide Catalyst for Oxidation of Alcohols at Room Temperature. Asian Journal of Organic Chemistry. 2014, 3 (4), 421-424.

Thottumkara, A. P.; Bowsher, M. S.; Vinod, T. K. In Situ Generation of o-Iodoxybenzoic Acid (IBX) and the Catalytic Use of It in Oxidation Reactions in the Presence of Oxone as a Co-Oxidant. Org. Lett. 2005, 7 (14), 2933-2936.

Relevant Scale-Up Examples with Scheme

No scale-up examples identified.