Meto-Chloroperbenzoic acid

Oxidation of alkyl phenyl telluride with excess meto-chloroperbenzoic acid (MCPBA) (3-5 equiv) in methanol affords the replacement of the phenyltellurium moiety by a methoxy group, giving the corresponding methyl ethers - (method A). This reaction. 

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)]. 

DIBAH reduction of 4 at -78 °C provides the corresponding trans-allylic alcohol. Successive epoxidation with meto-chloroperbenzoic acid (MCPBA) yields a single syn epoxide 5. The stereochemical assignment is proven by a second experiment using the asymmetric Sharpless epoxidation protocol. Both MCPBA and the Sharpless protocol using (-)-diethyl D-tartrate provided 5. 

In the second step meto-chloroperbenzoic acid (MCPBA) epoxidizes the resulting bis-acetal from the /J-face. The weak 0-0 bond of MCPBA undergoes attack by electron rich substrates like alkenes. This reaction is syn stereospecific and believed to take place via transition state 48.30... 

The oxidation of sulfides to sulfoxides is a facile transformation for which many reagents have been employed in the literature. These include hydrogen peroxide, ozone, nitric acid, chromic acid or tert-butylhypochlorite. Here, meto-chloroperbenzoic acid is used to oxidize a-phenylthio ketone 14, and successive elimination of the resulting a-phenylsulfinyl ketone 15 by heating at reflux in benzene provides the or,ji3-unsaturated ketone 16. Because of their thermal instability sulfoxides easily undergo elimination. The mechanism is explained by Cram as stereospecific cw-elimination. ... 

There are a variety of stoichiometric oxidants that can be used in conjunction with 2,2,6,6-tetramethylpiperdine 1-oxyl (TEMPO), including TCCA, iodobenzene diacetate, meto-chloroperbenzoic acid (wi-CPBA), sodium bromite, sodium hypochlorite, and /V-chloi osuccinirnide. TEMPO can be used to oxidize primary alcohols to aldehydes or carboxylic acids, based on reaction conditions. A particularly attractive feature is that the product is usually isolated quite pure after concentration of the organic layer. 

The strong tendency for thiophene 5, 5 -dioxides (17.1.2) to nndergo cycloaddition processes is echoed by thiophene iS -oxides. Thus, when thiophenes are oxidised with meto-chloroperbenzoic acid and boron trifluoride (without which 5, 5 -dioxides are formed), in the presence of a dienophile, addncts from 2 + 4 addition can be isolated. Thiophenes that are 2,5- or 3,4-disnbstimted with bnlky gronps can be converted into isolable iS -oxides, which undergo cycloadditions syn to the oxide, as exemplified below. ... 

The oxidation of furyl-2-carbinols can prodnce 6-hydroxy-2//-pyran-3(6//)-ones (the Achmatowicz rearrangement), which have several synthetic nses, the most important in the heterocyclic context being for the formation therefrom of pyrylinm-3-olate species (11.1.7). The oxidation can be condncted with meto-chloroperbenzoic acid, vanadinm(lll) acetylacetonate with f-butyl peroxide, or with singlet oxygen (18.7). 

The one new Lycopodium quinolizidine not included in the recent review in Volume 72 is (-F)-cermizine D N-oxide (1154), isolated from L. obscu-rum together with cermizine D (1153) itself and five other tetracycHc alkaloids. Apart from full characterization by spectroscopic methods, the structure of 1154 was substantiated by correlation with cermizine D, oxidation of which with meto-chloroperbenzoic acid yielded a product identical... 

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