2-Iodoxybenzoic Acid (IBX): A Versatile Reagent

Biographical Sketches

Indresh Kumar was born in Meerut, Uttar Pradesh, India. He completed his MSc in organic chemistry at C. C. S. University Meerut, India, in 2000. In that same year, he joined the National Chemical Laboratory in Pune, India, where he is currently a PhD student with Dr. C. V. Rode. His main research interests are asymmetric catalysis, new synthetic methods for nitrogen heterocycles and natural product synthesis.

Introduction

The importance of hypervalent iodine reagents in organic chemistry has been demonstrated in recent years, and they have been found to have several desirable properties: they are mild, selective, efficient and eco-friendly. [1] 2-Iodoxybenzoic acid (IBX) has been developed as a powerful ­reagent for several organic transformations, and a recent surge in interest was driven by the publication of an improved method for its synthesis. [2a] IBX is a powerful ­single-electron transfer oxidant that readily accepts a new heteroatom-based ligand, and has been applied successfully for the construction of novel heterocycles.

Preparation

According to a new improved procedure, IBX can be ­prepared in very good yield by the oxidation of 2-iodobenzoic acid with Oxone;^2a this shows advantages over the previously reported methods. [2b]

Abstracts

(A) IBX oxidizes 1° and 2° alcohols to the corresponding aldehydes and ketones, without any over-oxidation, in DMSO at room temperature. [3] Using different solvent systems and higher temperatures, yields of 90-100% can be obtained. [4] Environmentally ­benign ionic liquids have also been used as solvents for this transformation. [5]
(B) IBX has been used to oxidize oximes and tosyl hydrazones to the corresponding carbonyl compounds. [6]
(C) IBX was used to oxidize saturated alcohols and carbonyl compounds [7a] to the corresponding a,b-unsaturated carbonyl ­system in one pot. It can also be used to oxidize the benzylic ­position. [7b]
(D) IBX reacts with certain unsaturated N-aryl amides (anilides) to form novel heterocycles such as d-lactams, cyclic urethanes, ­hydroxylamine and aminosugar building blocks. [8]
(E) In combination with an N-oxide (MPO), IBX was used to ­oxidize a carbonyl [9a] and its silyl enol ether [9b] to the corresponding a,b-unsaturated compounds in high yield at ambient temperature.
(F) A regioselective oxidation of phenols to o-quinones was performed with IBX. [10]
(G) Recently, IBX was used to convert nitrogen- and sulfur-­containing substrates to synthetically useful intermediates. [11]

References

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3b De Munari S. Frigero M. Santagostino M. J. Org. Chem.  1996,  61:  9272 

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8b Nicolaou KC. Baran PS. Zhong Y.-L. Barluenga S. Hunt KW. Karnich R. Vega JA. J. Am. Chem. Soc.  2002,  124:  2233 

9a Nicolaou KC. Montagnon T. Baran PS. Angew. Chem. Int. Ed.  2002,  41:  993 

9b Nicolaou KC. Gray DLF. Montagnon T. Harrison ST. Angew. Chem. Int. Ed.  2002,  41:  996 

10 Derek M. Andey AR. Van De Water RW. Pettus TRR. Org. Lett.  2002,  4:  285 

11 Nicolaou KC. Mathison CJN. Montagnon T. Angew. Chem. Int. Ed.  2003,  42:  4077