Hydroxy iodo benzenes

Heteroatom rings, such as that found in quinoline derivatives, can be generated from amino-ketones with [hydroxy(tosyloxy)iodo]benzene and perchloric acid. Cyclic imines are converted to pyridine derivatives with NCS and then excess sodium methoxide. ... 

Thiazole and its derivatives are conventionally prepared from lachrymatory, a-halo-ketones and thioureas (or thioamides) by Hantzsch procedure [146]. In a marked improvement, Varma et al. have synthesized the title compounds by the simple reaction of in situ-generated a-tosyloxyketones, from arylmethyl ketones and [hydroxy(tosyl-oxy)iodo]benzene (HTIB), with thioamides in the presence of K 10 clay using micro-wave irradiation (Scheme 6.43) the process is solvent-free in both the steps [147]. 

A one pot procedure for the preparation of 1,3-sclenazoles has been reported. The method, a variation on the Hantzsch synthesis, involves the a-tosylation of ketones 90 with [hydroxy(tosyloxy)iodo]benzene followed by treatment with selenoamides to give 1,3-selenazoles 91 in moderate to high yields <00S1219>. 

With a-hydroxy ketones and their related tosyloxy derivatives. The imidazo [2,T ]thiazole 364 was prepared by acetic acid-catalyzed cyclocondensation of 2-hydroxy-l,2-diphenyl-ethanone with thiophenyl-substituted 2-aminothiazole 363 (Equation 163) <2002MI110>. Under MW irradiation and in the presence of montmorillonite K-10 clay, a mixture of a-tosyloxyketones 365 and 2-imidazolidinethione led to the substituted 5,6-dihydro-imidazo[2,l- ]thiazoles 366 (Equation 164) <1998J(P1)4093>. When using a-tosyloxyacetophenone, prepared by reaction of acetophenone with [hydroxyl(tosyloxy)iodo]benzene (HTIB), 5-aminopyrazole 367 could be converted to imidazo[l,2- ]pyrazole 368 in basic medium (Equation 165) <2005JHC209>. 

An operationally simple procedure involving a variation of this reaction and relying on the use of a polymer-supported [hydroxy(sulfonyloxy)iodo]benzene with aromatic ketones or alcohols has also been published <2004S2673>. 

Hydroxy(bisphenoxyphosphoryloxy)iodo]benzene, C6H5I—OP(OC6H5)2 (1). 

In a different study, anthracene, phenanthrene, perylene 93 (Fig. 31), and 2,7-di-tert-butylpyrene underwent regioselective oxidative-substitution reactions with iodine(III) sulfonate reagents in dichloromethane to give the corresponding aryl sulfonate esters. The use of [hydroxy(tosyloxy)iodo]benzene, in conjunction with trimethylsilyl isothiocyanate, led to thiocyanation of the PAH nucleus. 

Detailed studies on the solution structure of [hydroxy(mesyloxy)iodo]ben-zene and [hydroxy(tosyloxy)iodo]benzene 17 suggest that in aqueous solution iodosylbenzene 18 exists as a monomeric iodonium ion form 136, if the pH is < 2.3, and as a neutral species 137 at pH > 5.3 through mildly alkaline conditions [216]. The monomer 137 is soluble only to the extent of about 3 x 10"3 M. Based on these finding, we propose a structure of 138 as a reactive species in the reaction using a combination of (PhIO)n 18 and BF3-Et20. 

The best known member among the various classes of these iodanes is undoubtedly [hydroxy(tosyloxy)iodo]benzene (HTIB), sometimes called Koser s reagent. It is prepared readily from (diacetoxyiodo)benzene and p-toluenesul-fonic acid monohydrate in acetonitrile. The same method using p-nitroben-zenesulfonic acid or 10-camphorsulfonic acid leads to the corresponding sul-fonyloxy analogs [41,42]. Of special interest are some iodanes of this type coming from a chiral ether. Their preparation was effected by direct oxidation with sodium perborate and the isolated diacetoxy derivatives were separately treated with p-toluenesulfonic acid in acetonitrile (Scheme 8) [43]. 

Methoxy(tosyloxy)iodo]benzene is obtained from [hydroxy(tosyloxy)iodo]-benzene and trimethyl orthoformate. This iodane has been used for the preparation of the (-)-menthyloxy analog by simple alcohol exchange upon mixing in dichloromethane equimolar quantities of it with (-)-menthol and concentrating under reduced pressure (Scheme 9) [44]. 

The oxidation with [hydroxy(tosyloxy)iodo]benzene or other oxidants of the chiral alcohol o-IC6H4C(Me)(C6H5)OH is of interest because it provides a chiral benziodoxole (Scheme 16) with f-BuOCl a I-chloroiodane is formed first and then it undergoes substitution with nucleophiles [54]. 

Chiral iodonium salts of the general type p-RC6H4C = CI+Ph X-, where R was S-2-methylbutyloxy or S-2-methylbutyloxycarbonyl and X was TsO or TfO, were prepared from silylated alkynes with either [hydroxy(tosyloxy)iodo]benzene or PhI(OTf)OI(OTf)Ph [138]. 

Polymer-bound alkynyl(phenyl)iodonium salts were prepared by refluxing polymer-bound [hydroxy(tosyloxy)iodo]benzene and some alkynes in dry chloroform [141]. 

An analogous reaction took place with some 6-substituted-2-methyl-4-quinolones and [hydroxy(tosyloxy)iodo]benzene [162] and also between 5-nitro-7-hydroxyquinoline and (diacetoxyiodo)benzene [163]. Depending on the solvent or the presence of alkali, either the iodonium salt or the 1,4-dipole could be isolated. 

Hydroxylated 1,4-benzoquinones and 1,4-naphthoquinones gave similarly the corresponding dipoles [164]. The amino analogs reacted in the same way to afford first isolable iodonium salts and then the imino dipoles (Scheme 54) [165]. It is noted that the open-chain methyl 2-aminocrotonate gave with [hydroxy(tosyloxy)iodo]benzene only the iodonium salt, i.e. -MeC(NH2) = C(COOMe)I+Ph TsO- [166]. 

Combinations of [hydroxy(tosyloxy)iodo]benzene (13, HTIB) with molecular iodine or N-iodosuccinimide in acetonitrile promote conversions of haloethynylcarbinols to /J-halo-/ -iodoenones (the McNelis rearrangement) [48 - 57]. When bromoethynylcarbinols are utilized, (Z)-/ -bromo-/J-iodoenones are generally formed with high stereospecificity. The McNelis rearrangement, exemplified in (Scheme 19) [15], has been demonstrated with a variety of cyclic and acyclic haloethynylcarbinols, and has recently been reviewed [8]. 

Recent developments in this area include the use of poly[hydroxy(tosyloxy)-iodo]styrenes [80], chiral 2-(a-alkoxyalkyl) analogs of [hydroxy(tosyloxy)-iodo]benzene [81 - 83], and iodine(III)-phosphonate and -phosphinate reagents [84] for C-oxygen bond formation at a-carbon. Oxysulfonylations at the a-carbon atoms of carboxylic anhydrides with [hydroxy(sulfonyloxy)iodo]arenes have also been documented [85]. 

More recently, sulfide oxidations with [hydroxy(tosyloxy)iodo]benzene (4, HTIB) have been reported [15]. Such reactions proceed readily in di-chloromethane at room temperature and stop at the sulfoxide stage (Scheme 2). HTIB can also be generated in situ from iodosylbenzene (5) and 10 mol% p-toluenesulfonic acid for catalytic oxidations of sulfides to sulfoxides [16]. Oxidations of unsymmetrical sulfides with the chiral (+)-10-camphorsulfonyloxy analog of HTIB afford the corresponding sulfoxides (82-92%) with low enan-tioselectivities (2.7-13.7% ee) [15]. 

Using other hypervalent iodine compounds or different reagent combinations, various functional groups can be introduced in the a-position of ketones. a-Tosylations of ketones can be achieved directly using [hydroxy(tosyloxy)-iodo]benzene 6. The major drawback is the low regioselectivity observed in these reactions, although the a-tosylation of silyl enol ethers circumvents this problem. In the last few years some efforts have been done in the synthesis of chiral hypervalent iodine compounds [48, 53-55,113-117], but only a few of them have been used successfully in stereoselective synthesis. With chiral derivatives of type 59 it is possible to a-tosylate propiophenone with about 40% ee [56,118,119]. 

Hydroxy(tosyloxy)iodo]benzene, CH3C6H4S03l(0H)C6H5 (1), 14, 179-180. 

Conventional preparations of thiazoles and 2-aroylbenzo[fc]-furans require the use of lachrymatory a-haloketones and thioureas (or thioamides). To avoid this problem, Varma et al. have synthesized various hetero cycles via solvent-free reactions of thioamides, ethylenethioureas and salicylalde-hydes with a-tosyloxyketones that are generated in situ from arylmethyl ketones and [hydroxy(tosyloxy)iodo]benzene (HTIB) under microwave conditions (Scheme 15) [70]. 

Treatment of thiochroman-4-one and some 2-substituted derivatives with [hydroxy(tosyl)iodo]benzene (HTIB) admixed with anhydrous sodium sulphate and in the absence of solvent affords the sulfoxide 325 together with some thiochromone (Equation 58) <2004ARK183>. 

Diacetoxyiodo)benzene Aldrich, Fluka, Lancaster, Merck [Bis(trifluoroacetoxy)iodo]benzene Aldrich, Fluka [Bis(trifluoroacetoxy)iodo]pentafluorobenzene Aldrich, TCI America Iodosobenzene ICN, TCI America 2-Iodosobenzoic acid Aldrich, Fluka [Hydroxy(tosyloxy)iodo]benzene Aldrich Diphenyliodonium-2-carboxylate Lancaster... 

The standard method for the preparation of [hydroxy(tosyloxy)iodo]benzene (HTI) is the reaction of (diacetoxyiodo)benzene (DIB) with /Moluenesulphonic acid hydrate. 

Hydroxy(trifyloxy)iodo]-4-[(phenyl)(trifyloxy)iodo]benzene, 2 [23]... 

Such products are normally obtained with [hydroxy(tosyloxy)iodo]benzene (Section 7.3.5), which, however, did not work in this particular case. 

A reaction of considerable interest is the Hofmann type degradation of primary carboxamides to amines. Several examples have been reported of such efficient conversions, notably with the system IOB in formic acid (in water of acetonitrile), which forms in situ PhI(OOCH)2 [44], Other hypervalent iodine reagents have also been used extensively for these transformations (Sections 4.4.1 and 7.4.1). Yields may vary widely as illustrated for three similar amines obtained from the corresponding carboxamides with IOB-formic acid and with [hydroxy-(tosyloxy)iodo]benzene [45] ... 

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