O-Iodosobenzoate

Oxidation by the Dess-Martin Reagent. Another reagent that has become important for laboratory synthesis is known as the Dess-Martin reagent,28 which is a hypervalent iodine(V) compound.29 The reagent is used in inert solvents such as chloroform or acetonitrile and gives rapid oxidation of primary and secondary alcohols. The by-product, o-iodosobenzoic acid, can be extracted with base and recycled. 

Parker D.J., and Allison, W.S. (1969) The mechanism of inactivation of glyceraldehyde 3-phosphate dehydrogenase by tetrathionate, o-iodosobenzoate, and iodine monochloride. J. Biol. Chem. 244, 180-189. 

Another example of rapid turnover in a micellar system is the cleavage of carboxylic and phosphate esters by o-iodosobenzoate in cationic micelles. This reaction was not studied with a functional micelle, but it is useful to note it in this context (Moss et al., 1983, 1986). 

One of the earliest reports on the use of dendrimers in catalysis is the unimolecu-lar decarboxylation of 6-nitro-benzisoxazole-3-carboxylate in the presence of a dendrimer comprising ether dendrons which are functionalized at their periphery with tetra-alkylammonium cations (e.g. 20, Scheme 21) [30]. In aqueous media, the quaternary ammonium groupings promote the reactivity of organic anions which presumably bind in high concentration to the polycationic periphery of the dendrimer. The latter species enhances the rate of the bimolecular hydrolysis of p-nitrophenyl diphenyl phosphate catalyzed by o-iodosobenzoate ion. 

Ketones can be a hydroxylated in good yields, without conversion to the enolates, by treatment with the hypervalent iodine reagents162 o-iodosobenzoic acid163 or phenyliodoso acetate PhI(OAc)2 in methanolic NaOH.164 The latter reagent has also been used on carboxylic esters.165 02 and a chiral phase transfer catalyst gave enantioselective a hydroxylation of ketones, if the a position was tertiary.166... 

Hydrolysis with 1.3 M NaOH, resulting in o-iodosobenzoic acid (39) that can be separated by washing with an aqueous sodium bicarbonate solution. 

The o-iodosobenzoic or o-iodobenzoic acids, recovered from the work-up of oxidations with Dess-Martin periodinane, can be recycled back to this oxidant by oxidation to IBX, followed by transformation of IBX into Dess-Martin periodinane.2... 

In this work-up, the periodinane species 38s—resulting from the reduction of Dess-Martin periodinane—is hydrolyzed to o-iodosobenzoic acid,1 which is removed in the basic aqueous solution that is used for hydrolysis. This work-up is suitable for substrates that are not sensitive to aqueous base. 

Nitrodiphcnyl phosphate (195) in aqueous micellar hexadecyltrimethylammonimn chloride (CTAC1) in phosphate buffer at pH 8 is cleaved by l,3-dihydro-l-oxido-3-methyl-l,2,3-benziodoxaphosphole 3-oxide (196) and by l-//-l-oxido-5-methyl-l,2,3-benzodoxathiole 3,3-dioxide (197) 167 (196) and (197) were about 50 times less reactive towards o-iodosobenzoate (198). 

Several cyclic A3-iodanes of diverse structure have been reported over the years since Victor Meyer s o-iodosobenzoic acid, IBA, whose systematic name is 1 -hydroxy-1,2-benziodoxol-3(lH)-one. A recent review on benziodoxoles presents in detail their preparation and interconversions [51]. In Scheme 13 appears a collection of the main types of A3-iodanes which contain either a benziodox-ole ring or a 5-membered-ring with iodine, oxygen and another atom. 

Many of these iodanes are formed by oxidation of ortho-iodobenzoic acids or certain orf/zo-iodophenylated alcohols with Cl2, AcOOH, f-BuOCl, CF3OF or magnesium monoperoxyphthalate. Among A3-iodanes more important are those derived from o-iodosobenzoic acid which is obtained from the mild oxidation of o-iodobenzoic acid. An improved yield for o-iodosobenzoic acid was obtained by hydrolysis of its acetyl derivative which in turn was prepared from o-iodobenzoic acid and acetyl nitrate in acetic anhydride, at room temperature (Scheme 14) [52]. 

More drastic conditions, i.e. fuming HN03 in (CF3C0)20 were required for the preparation of some zwitterionic pyridinium analogs of o-iodosobenzoic acid (Scheme 15) [53]. 

In the same way 7-chloro-o-iodosobenzoic acid reacted with AgOPO(OPh)2 to provide the O-(diphenylphosphoryl) derivative of o-iodosobenzoic acid [55]. 

Another type of reactivity is due to the enhanced nucleophilicity of the hydroxyl group of o-iodosobenzoic acid. For example, o-iodosobenzoic acid reacts with silyl triflate or other silyl sulfonates to afford O-substituted sulfonates [56]. 

The O-tert-butyloxy derivative of o-iodosobenzoic acid is of interest because of its synthetic utility. In contrast to the facile reaction of tort-butyl hydroperoxide with iodosylbenzene (at - 80 °C), no ligand exchange was observed with this hydroperoxide and o-iodosobenzoic acid, even at room temperature. Treatment of o-iodosobenzoic acid with BF3 Et20, however, provided enough activation for the exchange to take place (Scheme 17) [57]. 

Related compounds are the 7-carboxamido-benziodoxoles which were obtained from o-iodosobenzoic acid upon reaction with trimethylsilyl triflate and the amides (Scheme 28) [78]. Similarly, with trimethylsilyl azide, the azido-analogs were formed as described recently (Scheme 29) [76,79,80]. 

Several solid supports have been employed for the attachment of o-iodosobenzoic acid, including silica gel, titania and nylon [89]. Two polymer-supported o-iodoxybenzoic acid reagents have recently been reported. The first was obtained by attaching a carboxymethyloxy derivative of f-butyl o-iodo-benzoate to an aminopropylated silica gel and oxidation with oxone [90]. The second involved chloromethylated polystyrene which was coupled with methyl 5-hydroxy-2-iodobenzoate and eventually oxidized by Bu4NS05H/MeS03H [91]. Some of these polymeric reagents appear in Scheme 31. 

Alkynyl(aryl)iodonium salts where aryl was the o-carboxyphenyl group were obtained from silylalkynes and o-iodosobenzoic acid [139]. It is noted that the first alkynyl iodonium salts were obtained in low yield from terminal alkynes. This approach was perfected recently, so that a range of substrates upon reaction with p-MeC6H4IO in aqueous HBF4, with catalysis by HgO, afforded alkynyl (tolyl)iodonium salts [140]. 

Mahoney, W. C., and Hermodson, M. A. (1979). High-yield cleavage of tryptophanyl peptide bonds by o-iodosobenzoic acid. Biochemistry 18, 3810-3814. 

As already oudined, inhibition is essentially complete when caused by reagents that react with sulfhydryl groups (for example, p-chloro-mercuribenzoate, p-mercuribenzoate, o-iodosobenzoate, L-ascorbic acid silver, cupric, and mercuric ions iodine, and ferricyanide) this inactivation can be reversed to some extent by hydrogen sulfide and by cysteine. Lineweaver—Burk graphs have shown that the action of L-ascorbic acid is noncompetitive, and L-ascorbic acid acting in the presence of cupric ions probably causes formation of an inactive cuprous-enzyme. The action of p-chloromercuribenzoate on barley beta-amylase has been shown to be a competitive inhibition. In contrast, the soya-bean p-chloromercuribenzoate inhibition is noncompetitive, and the extent of inhibition is inversely related to the concentration of acetate ion. The latter exhibits a protective effect, and there... 

Ketones having at least one hydrogen next to the carbonyl group can be hydroxylated to form a-hydroxy ketones (acyloins). Acetophenone is oxidized to a-hydroxyacetophenone by o-iodosobenzoic add. In the presence of potassium hydroxide and methanol, dimethyl acetal is obtained, which on subsequent hydrolysis gives the hydroxy ketone in 83% yield (equation 400) [790],... 

Vesicles of dioctadecyldimethylammonium chloride (DODAC) are relatively resistant to permeation of organic anions at 25 °C, at imposed exolendo pH gradients of 3 units. Thiophenolate anions, for example, can not be oxidized by o-iodosobenzoate if both reagents are encapsulated in DODAC vesicles (Figure 4.20). Reaction occurs immediately after addition of some ethanol. 

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