Iodobenzene diacetate reagent

Several organohypervalent iodine reagents have been used for the oxidation of alcohols and phenols such as iodoxybenzene, o-iodoxybenzoic acid (IBX), bis(trifluoroa-cetoxy)iodobenzene (BTI), and Dess-Martin periodinane etc. But the use of inexpensive iodobenzene diacetate (IBD) as an oxidant, however, has not been fully exploited. Most of these reactions are conducted in high boiling DMSO or toxic acetonitrile media that results in increased burden on the environment. 

The third modification of the Hunsdiecker reaction is the so-called Sudrez modification,21 where the steroidal acids were treated with hypervalent iodine reagent in CCI4 to prepare steroidal chloride. The Sudrez modification also works for bromination using iodobenzene diacetate, bromine, and CH2Br2 as the solvent under irradiation as exemplified by transformations 14—>15.22 Unlike many variations described before, the Suarez modification tolerates a variety of functional groups. 

Preparation. The reagent can be prepared conveniently by dissolution of iodobenzene diacetate (formerly named iodosobenzene diacetate) in warm trifluoroacetic acid (53% yield). Other methods have been reported. 

Organohypervalent iodine reagents such as iodoxybenzene, o-iodoxybenzoic acid (IBX), bis(trifluoroacetoxy)iodobenzene (BTI), and Dess-Marhn periodinane have been used for the oxidation of alcohols and phenols. Most of these reactions are conducted in high-boiling DMSO or relahvely toxic acetonitrile, which increase the burden on the environment. Further, the use of inexpensive iodobenzene diacetate (IBD) as an oxidant has not been fully exploited. Varma et al. have reported the first use of supported iodobenzene diacetate as an oxidant. In this novel oxidative protocol, alumina-supported IBD under solvent-free conditions rapidly converts alcohols to the corresponding carbonyl compounds in almost quantitative yields. The use of alumina as a support improved the yields markedly as compared to neat IBD (Scheme 2.2-40). 1,2-Benzenedimethanol, however, undergoes cyclization to afford l(3H)-isobenzofuranone [116]... 

In a complementary approach for preparing a-ketotriflates Varma and Kumar used the combination of iodobenzene diacetate and trifluoromethanesulfonic acid to prepare p-oxobis[trifluoromethanesulfonato(phenyl)iodme] 207 in situ. This reagent cleanly converted aromatic a-methyl ketones to the corresponding a-ketotriflates 204, which reacted with nitriles to afford 2-alkyl-5-aryloxazoles 206 in variable yield (Scheme 1.58). Mechanistically, the authors proposed the same... 

Competitive kinetic experiments show that PS gels increase the lifetimes of reactive intermediates from seconds to minutes. Generation of benzyne in solution produces the dimer, biphenylene, if no reagent is present trap the benzyne. The polymer-bound benzyne in Scheme 30 either dimerizes or is trapped by tetraphenylcyclopentadienone. Sequential addition of iodobenzene diacetate and tetraphenylcyclopentadienone to the polymer gave yields of the tetraphenylnaphthalene that decreased as the time between addition of the two reagents increased. The lifetime r of benzyne in the 2% cross-linked, DF 0.11 PS was established as 0.6[Pg.881]

The bromination and oxidation of securinine have been reported (Scheme 87). Oxidative difunctionalization of 2-amino-4//-pyrans occurs with iodobenzene diacetate and A -chlorosuccinimide reagents. An oxidative rearrangement of [7]helicene by heating with iron(n) chloride and aluminium(III) chloride involves skeletal rearrangement with the loss of helicity (Scheme 88). ... 

Considerable interest has been expressed in the development of direct methods for the synthesis of a-hydroxy ketones using nontoxic hypervalent iodine reagents and which involve the foUowing methods reaction of a ketone with iodobenzene diacetate in the presence of potassium hydroxide in methanol and then hydrolysis of the dimethylacetals oxidation of the enol sUyl ether of acetophenone using the s) tem iodosobenzene/boron trifluoride efherate/water in methylene chloride at—40°C and reaction of ketones with [fcis(trifluoroacetoxy)]iodobenzene and trifluoroacetic acid in acetonitrile-water under acidic conditions. "... 

Preparation. The reagent is prepared by stirring iodosobenzene diacetate with iN sodium hydroxide, collecting and drying the solid, and macerating it with chloroform to remove a little iodobenzene. This procedure is preferable to an older one involving alkaline hydrolysis of iodosobenzene dichloride because iodoso-... 

Similarly, for an oxidant that contains an indirectly activated oxygen, the preparation method can always be used to determine the oxidant. For example, lodosylbenzene (PhlO), a common oxidant, is made by treatment of the hyperva-lent iodine reagent PhI(OAc)2 with sodium hydroxide. The diacetate is made from the action of peracetic acid and acetic acid on iodobenzene. Thus, the iodosylben-zene oxidant can be traced to hydrogen peroxide, which is used to make the peracetic acid. 

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