M-CPBA

Sharpless and Masumune have applied the AE reaction on chiral allylic alcohols to prepare all 8 of the L-hexoses. ° AE reaction on allylic alcohol 52 provides the epoxy alcohol 53 in 92% yield and in >95% ee. Base catalyze Payne rearrangement followed by ring opening with phenyl thiolate provides diol 54. Protection of the diol is followed by oxidation of the sulfide to the sulfoxide via m-CPBA, Pummerer rearrangement to give the gm-acetoxy sulfide intermediate and finally reduction using Dibal to yield the desired aldehyde 56. Homer-Emmons olefination followed by reduction sets up the second substrate for the AE reaction. The AE reaction on optically active 57 is reagent... 

Alkyl-1,4-dihydropyridines on reaction with peracids undergo either extensive decomposition or biomimetic oxidation to A-alkylpyridinum salts (98JOC10001). However, A-methoxycarbonyl derivatives of 1,4- and 1,2-dihydro-pyridines (74) and (8a) react with m-CPBA to give the methyl tmns-2- 2>-chlorobenzoyloxy)-3-hydroxy-1,2,3,4-tetrahydropyridine-l-carboxylate (75) and methyl rran.s-2-(3-chlorobenzoyloxy)-3-hydroxy-l,2,3,6-tetrahydropyridine-l-carboxylate (76) in 65% and 66% yield, respectively (nonbiomimetic oxidation). The reaction is related to the interaction of peracids with enol ethers and involves the initial formation of an aminoepoxide, which is opened in situ by m-chlorobenzoic acid regio- and stereoselectively (57JA3234, 93JA7593). 

Sdieire 3.2fl. Steieochemlcel ecpectc of ellyllc cubctitutic end eppllcetlon In the cynthecic of (i-)-dlhydionepetelecti (m-CPBA = m-chloiopeibenzolc ecld) [106]. 

An interesting oxidative ring-opening reaction is shown in Scheme 2.36. Oxidation of vinylaziridines 138 with m-CPBA gave 142 through [2,3] Meisenheimer... 

The phenomenon that early transition metals in combination with alkyl hydroperoxides could participate in olefin epoxidation was discovered in the early 1970s [30, 31]. While m-CPBA was known to oxidize more reactive isolated olefins, it was discovered that allylic alcohols were oxidized to the corresponding epoxides at the same rate or even faster than a simple double bond when Vv or MoVI catalysts were employed in the reaction [Eq. (2)] [30]. 

Dimethyldioxirane DMDO discovered by Murray and coworkers, is a superior choice for the epoxidation of most olefins, giving comparable or higher yields than m-CPBA-based epoxidation [21]. Proceeding rapidly under neutral and mild conditions, it is especially well suited for the synthesis of sensitive epoxides of enol esters, enol lactones [22], and enol ethers [23]. The reaction is stereospecific, gen-... 

Cp = 7 -C5H5 m-CPBA = m-chloroperbenzoic acid Scheme 45 Oxidation of molybdenum polysulfido complexes... 

As mentioned in Sect. 2.2, phosphine oxides are air-stable compounds, making their use in the field of asymmetric catalysis convenient. Moreover, they present electronic properties very different from the corresponding free phosphines and thus may be employed in different types of enantioselective reactions, m-Chloroperbenzoic acid (m-CPBA) has been showed to be a powerful reagent for the stereospecific oxidation of enantiomerically pure P-chirogenic phos-phine-boranes [98], affording R,R)-97 from Ad-BisP 6 (Scheme 18) [99]. The synthesis of R,R)-98 and (S,S)-99, which possess a f-Bu substituent, differs from the precedent in that deboranation precedes oxidation with hydrogen peroxide to yield the corresponding enantiomerically pure diphosphine oxides (Scheme 18) [99]. 

Triazoline imino sugar derivatives 297 that are prospective glycosidase inhibitors have been prepared as single diastereomers in high yield via an lAOC reaction of in situ generated azido alkene 296 (Eq. 32) [78]. m-CPBA oxidation of the dithioacetal groups in the 0-acetylated 5-azido-5-deoxydibenzyl dithio-acetal of o-xylose or D-ribose 294 to the bis-sulfone 295, followed by loss of HOAc between C-1 and C-2 provided the lAOC precursor 296. 

Methods A oxidation with m-CPBA, B oxidation with (-l-)-MPCA. 

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