Meto-Chloroperoxybenzoic acid

After florisil (magnesium-silicate) filtration and concentration, crude 18 was treated with a THF solution of a 1 1 mixture of sodium iodide and meto-chloroperoxybenzoic acid (MCPBA) yielding in 67 % (from 5) the cr-iodo ketones 6. The ratio of diastereomers in this mixture was not described further. Mechanistically MCPBA oxidizes the iodide ion to an iodoniumion-species, which reacts with the double bond, generating intermediate 21. After TMS is removed the tricyclic iodonium ion collapses to desired 6. In contrast to this transformation the researchers observed no useful yields by direct treatment of the silyl enol ether with molecular iodine. 

The most commonly used peroxy-acid is known as m-CPBA, or meto-ChloroPeroxyBenzoic Acid. m-CPBA is a safely crystalline solid. Here it is, reacting with cyclohexene, to give the epoxide in 95% yield. 

Reaction of an alkene with an oxidising agent, such as a peroxy-acid, leads to the formation of an epoxide ring. A number of peroxy-acids can be used, although the most common is meto-chloroperoxybenzoic acid (mCPBA). This is a fairly stable, white solid, that is commercially available. The reaction is believed to take place by electrophilic attack of the peroxy-acid on the double bond (5.39). 

Cleavage of the trityl ether from the Manlll with formic acid followed by the phos-phitylation with phosphoramidite 25 and meto-chloroperoxybenzoic acid (m-CPBA) oxidation at —40°C gave phosphotriester 39 as a 1 1 mixture of diastereomers. Upon removing the cyclohexanone ketal from the inositol, the corresponding diol was converted into an orthoester using the trimethyl orthoester of myristic acid. Hydrolysis of the orthoester in the presence of Yb(OTf)3 installed the myristate ester... 

In 1983, Corey and coworkers disclosed a stereocon-trolled synthesis of LTB (157) using commercial tri-0-acetyl-D-glucal (158) as akey starting material (Scheme 3.38) [90]. Oxidation of 158 with meto-chloroperoxybenzoic acid provided lactone 159, which was converted into 160 using Zn(Hg) and HCl. Rearrangement of the double bond with l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) produced... 

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