Iodonium diacetate

Oxo-bridged diiodonium triflate [Zefirov s reagent), a useful reagent for the synthesis of triflate esters and iodonium salts, can be prepared by the treatment of lodosobenzene with triflic anhydride [92] or by the reaction of lodobenzene diacetate with tnflic acid [93] (equation 44). 

Iodosobenzene diacetate is used as a reagent for the preparation of glycol diacetates from olefins,9 for the oxidation of aromatic amines to corresponding azo compounds,10 for the ring acetylation of N-arylacetamides,11 for oxidation of some phenols to phenyl ethers,12 and as a coupling agent in the preparation of iodonium salts.13 Its hydrolysis to iodosobenzene constitutes the best synthesis of that compound.14... 

Ynol tosylates are synthesized from terminal alkynes via a unique sequence (equation 10). The hypervalent organoiodine compound 32, prepared by treatment of iodosoben-zene diacetate with /i-toluenesulfonic acid, reacts with the terminal alkynes 31 to give the iodonium tosylates 33, which are then treated with 10 mol% of CuOTf or AgOTf to afford the ynol tosylates 34. Finally, the ynol tosylates 34 are converted into lithium ynolates 35 by treatment with MeLi. The ynolates are trapped with r-butyldimethylsilyl chloride, triethylgermyl chloride and tributylstannyl chloride to give the silyl ynol ethers 36, the germyl ketenes 37 and the stannyl ketene 38. ... 

Because detailed mechanistic information is not available, a tentative mechanism is proposed here. It is assumed that iodine first adds to the double bond to form an iodonium cation in a process similar to the bromination of alkene, then nucleophilic attack from acetate leads to the formation of the ra/25 -o -iodoacetate. In the presence of silver acetate, a-iodo leaves to give a dioxoanyl carbocation, which is attacked by the second acetate anion to give 1,2-diacetate. Upon hydrolysis or LiAlH4 reduction, diacetate is transformed into trans-l,2-diol. The displayed mechanism is similar to the one proposed by Sudalai. ... 

An interesting application of phenyliodine diacetate is the reaction with carbon acids such as / -diketones under mild, basic conditions to yield iodonium ylides (EWG = electron-withdrawing group) ... 

Oxidation of carbonyl compounds with organo-hypervalent iodine reagents has been reviewed. The hypervalent iodine oxidation of several a-substituted 2,4-dihydroxyacetophenones (12) (Scheme 6) using phenyliodonium diacetate (PIDA) proceeds via rearrangement of an iodonium ylide (13) to afford novel o-iodophenoxy ethers (14). ... 

Preparation by hypervalent iodine oxidation of 5-bromo-resacetophenone with iodosobenzene diacetate in the presence of potassium hydroxide in methanol via the rearrangement of iodonium yUde previously formed (35%) [3511]. 

The rhodium complex also catalyzed the cyclopropanation of iodonium ylides 159 that was prepared from malonic esters (Scheme 1.75) [120]. The treatment of a malonic ester with phenyhodonium diacetate gave corresponding iodonium ylides, which underwent smooth cyclopropanation with various alkenes. It was shown that these two steps... 

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