Pentavalent iodine

Synthetically useful phosphorane-derived phenyliodonium triflates have been synthesized from the highly electrophilic pyridinium complex 20 <2002TL2359>. Similarly, benziodoxole 21 reacts with trimethylsilyl trifluoro-methanesulfonate (TMSOTf) and pyridine to form a precipitate of complex 22 (Equation 6) <2002TL5735>. The first example of a pentavalent iodine complex with a chelating polydentate nitrogen ligand 24 was obtained from diacetate 23 under similar conditions (Equation 7) <2002TL5735>. 

The first two types, (a) and (b), called iodanes, are conventionally considered as derivatives of trivalent iodine I(+3). The next two, (c) and (d), periodanes, represent the most typical structural types of pentavalent iodine I(+5). The structural types (e) and (f) are typical of heptavalent iodine I(+7). 

Oxidation. This pentavalent iodine compound oxidizes primary or secondary alcohols to aldehydes or ketones in generally high ield (85-95%), Benzylic alcohols are oxidized more readily and also in high yield. Work up of the reactions involves conversion... 

Review.4 Varvoglis has reviewed the chemistry of tri- and pentavalent iodine (217 references). 

Iodine is produced by similar methods, namely, oxidation of the iodide anion from brines by chlorine. However, iodine is also produced in a reductive process by reacting NalOs, extracted from the natural source of Chilean saltpeter, with sodium hydrogen snffite. The pentavalent iodine is reduced to iodide (equations), which is then treated and oxidized with a sufficient amonnt of the mother liquor to liberate elemental iodine (equation 5). In contrast to chlorine and bromine, which have large industrial uses, iodine has no predominant commercial use. 

Zhdankin and co-workers reported <2004TL2719> the use of DMDO lb in the preparation of new pseudobenzio-doxole-based pentavalent iodine compounds 139, amides of 2-iodoxybenzenesulfonic acid, which are potentially useful reagents for mild oxidation of alcohols. 

Several oxidants are derivatives of iodoaromatic compounds containing trivalent and pentavalent iodine. 

In the older literature, derivatives of iodine(III) were known under the general name of iodinanes, while compounds of pentavalent iodine were called periodinanes. According to the 1983 lUPAC recommendations Treatment of variable valence in organic nomenclature (lambda convention) [126], these old names were replaced by -iodanes for iodine(III) and -iodanes for iodine(V) compounds. In the lambda nomenclature. 

The mechanism is expected to be rather simple water attacks one of the pentavalent iodine centers, with iodate (103 ) acting as the leaving group ... 

Given the variety of iodine valence states in organoiodine compounds, the A nomenclature (see Section 1.26) will prove useful for our discussion. Dichloroiodobenzene is thus a A -iodane, the superscript being essentially the valence of the atom in question. As shown below, a number of other A -iodanes such as iodobenzene diacetate are also readily accessible from iodobenzene the pentavalent iodine compound iodoxybenzene is shown below in a different color to distinguish it from the other trivalent compounds. 

Peroxyacid treatment, followed by heating in water, converts iodobenzene to iodoxyben-zene, a pentavalent iodine compound, as shown above. 

Coordination of the alcohol to the pentavalent iodine of IBX is a reasonable starting point ... 

The five-membered pentavalent iodine heterocycles represent a particularly important class of hypervalent iodine compounds. Cyclic iodine(V) compounds, such as IBX 212 and DMP 213, have found broad practical application as mild and selective reagents for the oxidation of alcohols and some other useful oxidative transformations. Several comprehensive reviews of the chemistry and synthetic applications of IBX and DMP have been published (2011JOC1185, 2006ARK26, 2010T7659, 2011AGE1524, 2001ACE2812). 

Amides of 2-iodoxybenzoic acid (IBX-amides) 246 can be prepared by the dioxirane oxidation of 2-iodobenzamides 245 (Scheme 56) in the form of stable, microcrystalline soHds moderately soluble in dichloromethane and chloroform (2003ACE2194). This procedure has been used for the synthesis of the amides 246 derived from various types of amino compounds, such as esters of a-amino acids, esters of P-amino adds, and (R)-l-phenylethylamine. A single-crystal X-ray analysis of the phenylalanine derivative [246, R = (S)-CH(CH2Ph)C02Me] shows a close intramolecular contact of 2.571 A between the pentavalent iodine center and the oxygen atom of... 

The soluble and stable pentavalent iodine N-(2-iodylphenyl)acylamides 252 with a pseudo-benziodoxazine structure have been synthesized in good... 

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