Oxidation phenyliodine

Oxidation. Phenyliodine ditrifluoroacetate is more effective for various dehydrogenations than iodobenzene diacetate. Representative oxidations are formulated. Alcohols are oxidized preferably in the presence of a tertiary amine... 

Polymer-bound phenyliodine difluoride, which also has been used as a reagent to add fluorine to alkenes, can be prepared by the addition of xenon difluoride to the polymer [134, 135 136] Methyl iodide is converted to trifluoro methyliodine difluoride by treatment with fluorine at -110 C [137] Perfluoro-alkyliodine tetrafluorides could be synthesized from the perfluoroalkyliodine difluorides and fluorine [138] or chlorine trifluoride [139] Perfluoroalkyl [140] and perfluoroaryl [141] iodides are oxidized to the corresponding iodine difluorides by chlorine trifluoride. 

Thieno benzazepine 109 was synthesized in moderate yield by oxidative biaryl-coupling using the hypervalent iodine reagent phenyliodine(lll)bis (trifluoroacetate) (FIFA) and BF3 OEt2 as the activating agent in methylene chloride (Equation (16) (2002X8581)). 

While the silver and zinc salts were effective Lewis acids for these cyclizations, Kikugawa and coworkers reported that the alkoxynitrenium ions could be generated directly from hydroxamic esters (4) using hypervalent iodine oxidants such as hydroxy(tosyloxy) iodobenzene (HUB) and phenyliodine(lll)bis(trifluoroacetate) (PIFA) . Presumably, with such reagents the reactions proceed through A-(oxoiodobenzene) intermediates (54), which can themselves be regarded as anomeric hydroxamic esters and sources of alkoxynitrenium ions (55) (Scheme 11). 

Oxidation of hydroxamic esters in an alcoholic solvent may prove to be useful in certain cases. Phenyliodine(III)bis(trill uoroacetate) (PIFA) oxidation of the proline derivative (185) in trifluoroethanol afforded a 26% yield of the A-methoxy-Af-trifluoroethoxy derivative (187), presumably via an intermediate Af-methoxy-A-acylnitrenium ion (186) (equation 23). ... 

An interesting new method to cyclize phenylalkylazides to the quinone imine 29 by oxidative cyclization with phenyliodine (III) bis(trifluoroacetate) (PIFA) was reported <99CPB241>. 

Isoxazolo[5,4- ]pyridines have been synthesized via cyclization under oxidative conditions using phenyliodine(iii) bis(trifluoroacetate) (PIFA) (Equation 10 Table 17) <1997SC2217>. 

Iodine-Mercury(II) oxide, 149 Lithium diisopropylamide-Potassium /-butoxide, 164 Molybdenum carbonyl, 194 Phenyliodine(III) diacetate, 242 Sulfuryl chloride, 284 Conjugate addition reactions Michael reactions Alumina, 14... 

Lithium diisopropylamide, 163 Phenyliodine(III) diacetate, 242 Tetrakis(triphenylphosphine)-palladium(O), 289 Trimethylamine N-oxide, 325 Containing one nitrogen—indoles Hexamethyldisilazane-Chlorotri-methylsilane, 141 Iron carbonyl, 152... 

Oxidative coupling of substituted bibenzyl ethers with phenyliodine(m) bis(trifluoroacetate) affords 6,7-dihydro-577-dibenzfo oxepines (Equation 17) <1998JOC7698>. 

Review.1 The reactions of C6H5I(OAc)2 are mainly oxidations in which iodine(III) is reduced to iodine(I) and closely resemble those of lead tetraacetate, such as cleavage of glycols. For this reaction, phenyliodine(III) bis(trifluoroacetate) is the preferred reagent (6, 301). 

Bis(4-chlorobenzenediazo) oxide, 3450 Bis(4-chlorobenzenesulfonyl) peroxide, 3452 7,/-Bis(3-chlorobenzoylperoxy)-4-chlorophenyliodine, 3787 1,7-B is (3 -chlorobenzoy lperoxy)phenyliodine, 3788... 

The oxidation of carbonyl compounds can be achieved with hypervalent iodine reagents quite easily. A general feature of these reactions is the electrophilic attack of the hypervalent iodine reagent at the a-carbon atom of a carbonyl group and a review on this chemistry has been published recently [6]. This leads to hypervalent iodine intermediates of type 55. These phenyliodinated intermediates are quite unstable and a variety of subsequent reactions are possible. Intermediates 55, Scheme 24, can be considered as umpoled substrates regarding the reactivity of the a-position of the initial carbonyl compounds. Major processes are the substitution by a nucleophile (see Sect. 3.5.1 Functionalization in the a-Position) or the introduction of a carbon-carbon double bond (see Sect. 3.5.2 Introduction of an a,/ -Unsaturation). 

In particular, (diacyloxyiodo)benzene such as phenyliodine(III) diacetate (PIDA) and phenyliodine(III) bis(trifluoroacetate) (PIFA) have received a great deal of attention due to their reactivities similar to those of heavy metal reagents or anodic oxidation, low toxicity, ready availability and easy handling. Accordingly, a variety of useful oxidation reactions using iodine(III) or iodine(V) reagents have been developed recently. A number of previous review articles and... 

Paquette et al. start with the bis-vinylogation of the same compound 29 [14], by Wittig-Horner reaction, reduction, and oxidation (Scheme 5). For the formation of the C17-C16 bond, the onti-aldol 41 (ds not reported) is obtained by treatment of the aldehyde 39 with the (Z)-boron enolate 40, bearing a dithioketal moiety that is later to be the C51-C54 side chain. 3-Hydroxy-assisted, diastereoselective reduction of the keto group at C15 gives 41, which is converted into intermediate 42 in five more steps. The dethioketalization of 41 is achieved with phenyliodine(m) bis(trifluoroacetate) [16], As in Nicolaou s synthesis, the N12-C13 amide bond is formed first, followed by a low-yielding (21%, even at a concentration of 1 him) macrolactonization to 3. Table 1 summarizes the benchmark data of the two total syntheses of sanglifehrin A (1). 

More recently, a new class of non-metallic oxidation reagents has been reported - the hy-pervalent iodine complexes [19]. Phenyliodine(III) diacetate (PIDA) and phenyliodine(III) bis(trifluoroacetate) (PIFA) have proven to be very efficient reagents that give rise to higher regioselectivity than other oxidants in some reactions and, more importantly, offer a mild and non-toxic alternative to the heavy metals. 

Ley and co-workers studied the applicability of immobilized phenyliodine(III) bis]acetate) as an oxidative coupling reagent in an effort to develop orchestrated multistep syntheses using... 

The treatment of isatin with sodium hypochlorite in acetic acid leads to 1-chloroisatin, an effective mild oxidizing agent for the conversion of alcohols to aldehydes and ketones110 and of indoles to 3-chloroindoles without formation of by-products111. N-[phenyliodine(III)] bisisatin can be obtained from the sodium salt of isatin and phenyliodine (IE) bistrifluoroacetate in 85% yield. This compound is a member of a group of iodine(III)imides,... 

Phenyliodine bis(trifluoroacetate) in combination with a Lewis acid has been shown to mediate selective oxidative cyanation of thiophenes at C-2 using TMSCN as the cyanide source <07JOC109>. Likewise, oxidative coupling of thiophenes with A-aromatic methanesulfonamides in the presence of PhI(OAc)2 in hexafluoroisopropanol (HFIP) takes place at C-2 of the thiophene, rendering for example the product 43 <07OL2553>. 

Oxidative coupling reactions involving pyrroles mediated by phenyliodine(III) bis(trifluoroacetate) (PIFA) have been reported these include the formation of bipyrroles <07S2913> and 2-cyanopyrroles <07JOC109>. 

Although arylpropanols afford chromans directly on treatment with phenyliodine bis(trifluoroacetate) (PIFA) in hexafluoropropan-2-ol <07T4052>, the use of certain iodinating complexes brings about concomitant oxidative intramolecular cyclisation and regioselective iodanation (Scheme 18) <07OL1995>. 

Hypervalent iodine(lll) was shown to catalyze the direct cyanation of iV-tosylpyrroles and -indoles under mild conditions, without the need for any prefunctionalization <2007JOC109>. Phenyliodine(m) bis(trifluoroacetate)-induced oxidative regioselective coupling of pyrroles in the presence of bromotrimethylsilane gave a series of electron-rich bipyrroles <2007S2913>. 

Environmentally benign oxidation of sulfides to sulfoxides was reported by Kita and co-workers by using iodine(III) reagents such as iodosobenzene (PhIO) or phenyliodine diacetate (PIDA) with KBr in water. 

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