TETRAHEDRON LETTERS Tetrahedron Letters 43 (2002) 569–572 Pergamon Synthesis and oxidation reactions of a user- and eco-friendly hypervalent iodine reagent Arun P. Thottumkara a and Thottumkara K. Vinod b, * a Macomb High School, Macomb, IL 61455, USA b Department of Chemistry, Western Illinois University, Macomb, IL 61455, USA Received 15 September 2001; revised 19 November 2001; accepted 20 November 2001 Abstract—Allylic and benzylic alcohols are cleanly oxidized to the corresponding carbonyl compounds in water or water–THF mixtures using a water-soluble derivative of o -iodoxybenzoic acid. A mechanism involving single electron transfer steps is proposed for this facile and eco-friendly oxidation protocol. © 2002 Elsevier Science Ltd. All rights reserved. 1. Introduction Hypervalent iodine reagents, due to their low toxicity and ready availability, have attracted considerable attention recently as mild and selective oxidizing agents. 1 Of the various hypervalent iodine reagents known, Dess–Martin periodinane (DMP), 1, 2 and o -iodoxybenzoic acid (IBX), 2, 3 are the most commonly used. Despite the nontoxic nature of these compounds and their ease of preparation, these reagents have certain drawbacks. Both reagents are potentially explosive and, thus, cannot be stocked in large quantities. In addition to this drawback, oxidation of alcohols using DMP are carried out in environmentally unsafe chlorinated solvents and reactions employing IBX are often limited in dimethyl sulfoxide (DMSO) due to the reagent’s insolubility in other common organic sol- vents. While oxidation reactions using both DMP and IBX tolerate the presence of moisture in the reaction medium, 1f,2c the presence of large amounts of water, when used as a solvent or co-solvent, is detrimental to the outcome of the oxidation reactions using these reagents. This is due to the fact that the mechanisms of oxidation with both the oxidizing agents involve reactive interme- diates formed in an equilibrium step that is disfavored with increasing concentrations of water. 1f,g A series of elegant papers from Nicolaou Laboratories have recently identified several new oxidative transforma- tions, including a selective oxidation of benzylic carbons using IBX. 4 These reactions were carried out either in DMSO or fluorobenzene/DMSO mixtures. Single elec- tron transfer (SET) reaction pathways have been pro- posed for these synthetic technologies. 4c,d,f A significant aspect of the new oxidative transformations that caught our attention is that the presence of water does not affect the outcome of these reactions. The ever-growing demand for eco-conscious chemical processes 5 and our interest in green-chemistry prompted us to synthesize a water-solu- ble derivative of IBX that could potentially behave as a green -oxidant capable of oxidizing alcohols in water, possibly via a SET mechanism (vide infra), similar to the one proposed by Nicolaou. In this paper we describe the synthesis of 3, a water-soluble derivative of IBX, which we call modified IBX (mIBX), and oxidation of allylic and benzylic alcohols using 3 in water and other eco- friendly solvents. 2. Results and discussion 2.1. Synthesis of mIBX The synthesis of mIBX, 3, is readily accomplished from commercially available 3-nitrophthalic acid (4) as follows: esterification of 4 via the corresponding acid chloride gave nitrodiester, 5 (100%), which upon catalytic hydrogenation provided the aminodiester, 6 Keywords : hypervalent iodine reagent; oxidation; green-oxidant; sin- gle electron transfer. * Corresponding author. Tel.: 309-298-1379; fax: 309-298-2180; e-mail: mftkv@wiu.edu 0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved. PII:S0040-4039(01)02217-1