IBX Oxidation

17 April, 2014 / by SK / in Reactions

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General Characteristics

2-Iodoxybenzoic acid (IBX) is a mild and versatile oxidant. It can be easily prepared from 2-iodobenzoic acid and Oxone (See the Dess-Martin oxidation as reference).

IBX had long been rarely used as a reagent because of its poor solubility in organic solvents other than DMSO. New interesting reactions are being explored recently by Nicolaou and others.

General References

・Frigero, M.; Santagostino, M. Tetrahedron Lett. 1994, 35, 8019. DOI:10.1016/0040-4039(94)80038-3
・De Munari, S.; Frigero, M.; Santagostino, M. J. Org. Chem. 1996, 61, 9272. DOI: 10.1021/jo961044m
・Moore, J. D.; Finney, S. N. Org. Lett. 2002, 4, 3001. DOI: 10.1021/ol026427n
・Nicolaou, K. C.; Zhong, Y. L.; Baran, P. S. J. Am. Chem. Soc. 2000, 122, 7596. DOI: 10.1021/ja001825b
・Nicolaou, K. C.; Montagnon, T.; Baran, P. S.; Zhong, Y.-L. J. Am. Chem. Soc. 2002, 124, 2245. DOI:10.1021/ja012127+
・Nicolaou, K. C.; Mathison, C. J. N.; Montagnon, T. Angew. Chem. Int. Ed. 2003, 42, 4077. DOI:10.1002/anie.200352076

Reaction Mechanism

The addition of water is known to decrease the reactivity, which is rationalized by the reversible ligand exchange mechanism. (ref: J. Am. Chem. Soc. 2005, 127, 14146.)

Examples

Whereas the Dess-Martin reagent cleaves 1,2-diols, IBX can oxidize them without breaking them up.^[1]

IBX is also useful to prepare α,β-unsaturated ketones.^[2]

It can also oxidize benzylic methyl groups into aldehydes.^[3]

The oxidation of amines to imines is also possible with IBX.^[4]

The oxidation to carboxylic acids is possible by adding N-hydroxysuccinimide. The functional group selectivity is high.^[5a] Using Oxone as a reoxidant under heating conditions, IBX can be substoichiometric.^[5b]

Selective oxidation of secondary hydroxyl groups in the presence of primary hydroxyl groups is possible.^[6]

2-Iodobenzenesulfonic acid acts as a highly active oxidation catalyst. It forms a sulfonic acid analogue of IBX in situ.^[7]

The conversion of amides into nitriles with one-carbon dehomologation.^[8]

Experimental Procedure
Experimental Tips

IBX has well-known for its hazard risks as a potential explosive.^[9] Special caution is required when carrying out the reaction on a large scale.

References

[1]
[2]
[3]
[4]
[5] (a) Mazitschek, R.; Mulbaier, M. M.; Giannis, A. Angew. Chem. Int. Ed. 2002, 41, 4059. [abstract] (b) Thottumkara, A. P.; Bowsher, M. S.; Vinod, T. K. Org. Lett. 2005, 7, 2933. DOI: 10.1021/ol050875o
[6] Kuhakarn, C.; Kittigowittana, K.; Pohmakotr, M.; Reutrakul, V. Tetrahedron 2005, 61, 8995. DOI: 10.1016/j.tet.2005.07.051
[7] Uyanik, M.; Akakura, M.; Ishihara, K. J. Am. Chem. Soc. 2009, 131, 251. DOI: 10.1021/ja807110n
[8] Bhalarao, D. S; Mahajan, U. S.; Chaudhari, K. H.; Akamanchi, K. G. J. Org. Chem. 2007, 72, 662. DOI: 10.1021/jo0619074
[9] Plumb, J. B.; Harper, D. J. C&EN News 1990, July 16, 3.