General Procedure using mcpba

A modification of this method consists of the oxidative diacetoxylation of iodoarenes in acetic or trifluoroacetic acid using appropriate oxidants, such as periodates [149-151], chromium(VI) oxide [152], sodium percarbonate [153], m-chloroperoxybenzoic acid (mCPBA) [130, 154-158], potassium peroxodisulfate [159,160], HaOa-urea [161], Selectfluor [33] and sodium perborate [132]. The oxidation of iodoarenes with sodium perborate in acetic acid at 40 °C is probably the most general procedure that has been used for the small-scale preparation of numerous (diacetoxyiodo)-substituted arenes and hetarenes (Scheme 2.14) [132,133,162-166]. For example, the chiral diacetate 31 and several analogous... 

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... 

Racemic kjellmanionone (123) has also been prepared by direct oxidation of the potassium enolate of die ketone (122) with MCPBA and, if general, this would represent a convenient procedure. Oxidation of ketones with benzoyl peroxide is of no synthetic value (vide supra), but the process becomes useful if enolates are employed. Treatment of enone (126) with LDA in THF at 0 C followed by quenching with... 

The most widely accepted method for epoxidation of alkenes remains oxidation with organic peracids. The early work (up to 1970) in this field shows that a large number of dienes and polyenes were oxidized in this manner . The most commonly used peracids are peracetic, monoperphthalic and perbenzoic acids which are most dominant in industrial applications. On the other hand, in laboratory procedures m-chloroperbenzoic acid, MCPBA, is often used, with trifluoroperacetic acid cited in more difficult transformations. Recently, the transportation of m-chloroperbenzoic acid has been restricted and the use of other peroxygen agents has been gaining acceptance as a general alternative. Among the substrate types epoxidized it would be especially worthy to point out polyunsaturated... 

The same procedure was also applied to the synthesis of ketofuranosides [5] such as fructosides and psicosides, where the starting enol ethers contained an extra hydroxymethyl group linked to the double bond. This structural feature allowed the use, besides the MCPBA epoxidation, of the Sharpless epoxidation. Although the epoxidation reaction gave, in general, better results than in the former case, it is noteworthy that the stereoselectivity of the Sharpless epoxidation was somewhat unpredictable. This is probably due to the presence of a second hydroxyl group which can coordinate the titanium and, in some cases, counteract the normal eourse of the Sharpless epoxidation. 

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