Diaryliodonium triflates, preparation

Diaryliodonium salts (diaryl-A3-iodanes) are widely used as arylating agents. There are a number of methods available for their synthesis typically involving two or three steps.378,379 A recent one-pot approach, however, offers a simple and high-yielding access to unsymmetrical diaryliodonium triflates using meto-chloroperbenzoic acid (mCPBA) as the oxidant380 [Eq. (4.111)]. Moreover, symmetrical diaryliodonium salts can directly be prepared from iodine and arenes without the use of expensive aryl iodides [Eq. (4.112)]. 

Diaryliodonium triflates are prepared from ArfrOAc) and arenes in triflic acid. Hydrolysis of thioglycosides. Aqueous TfOH and Bu NIO effect hydrolysis of thioglycosides," probably by way of Pummerer reaction. 

Diaryliodonium triflates. An improved preparative method for aryl phenyli-odonium triflates (10 examples, 74-98% yield) involves reaction of arenes with this reagent in the presence of triflic acid. 

Several modified procedures for the preparation of diaryliodonium triflates have been reported in a more recent literature [382-384], Kitamura and Hossain have developed a one-pot reaction to obtain symmetrical diaryliodonium triflates in good yields directly from iodoarenes and aromatic substrates using K2S2O8 as an... 

Olofsson and coworkers have developed several efficient one-pot syntheses of diaryliodonium salts [385-390], A general and universal procedure provides both symmetrical and unsymmetrical diaryliodonium triflates 272 from both electron-deficient and electron-rich arenes 271 and aryl iodides 270 using mCPBA as the oxidant and trifiic acid (Scheme 2.78) [385-387]. The electron-rich diaryliodonium tosylates are prepared similarly using toluenesulfonic acid instead of trifiic acid as the additive [387]. Symmetrical diaryliodonium triflates can be synthesized by a modified one-pot procedure from iodine, arenes, mCPBA and trifiic acid under similar conditions [374,375]. A similar procedure based on a one-pot reaction of arylboronic acids, aryl iodides, mCPBA and BF3 -Et20 has been used for regioselective synthesis of unsymmetrical diaryliodonium tetrafiuoroborates [388,389]. In a further improvement of this approach, a range of... 

Other methods exploiting different reactions for in situ formation of the substituted azides in the one-pot click S5mthesis of substituted 1,2,3-triazoles in PEGs were developed. Thus, 1-aryl-subshtuted 1,2,3-triazoles 86 were prepared via the reaction of diaryliodonium triflate 85 with sodium azide, followed by the treatment with terminal alk5mes in aqueous PEG 400 under the copper(I) iodide catalysis (Scheme 50) [79]. The catalyst and the solvent were successfully recovered and reused in three cycles. 

Diaryliodonium salts are the most stable and well-investigated class of iodonium salts. The first example of these compounds, (4-iodophenyl)phenyliodonium bisulfate, was prepared by Hartmann and Meyer in 1894 from iodosylbenzene and sulfuric acid [368]. Diaryliodonium salts Ar2l+ X are air- and moisture-stable compounds, whose physical properties are strongly affected by the nature of the anionic part of the molecule. In particular, diaryliodonium salts with halide anions are generally sparingly soluble in many organic solvents, whereas triflate and tetrafluoroborate salts have a better solubility. The chemistry of aryl-and heteroaryliodonium salts has been extensively covered in several reviews [361,369,370]. 

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