CPBA oxidation

Nicolaou in his model system for an approach to the thiopeptide antibiotic thiostrepton, in particular, the elaboration of the quinaldic acid moiety. The tetrahydroquinoline 21 was converted to the A-oxide by /n-CPBA oxidation. Subsequent treatment with TFAA, to carry out the Boekelheide reaction, was followed by hydrolysis of the resultant ester to produce 22 as a mixture of alcohols. 

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. 

However, good yields of l,3-oxazolidin-2-ones were obtained through m-CPBA oxidation of N- and O-protected OZTs (Scheme 52).10... 

Scheme 37 m-CPBA oxidation of ladder polysilanes to hybrid silane/siloxane polymers (substituents /-Pr). 

Epoxidation of 632c with m-CPBA to 634, followed by silylation with bis(trimethylsilyl) acetamide (BSA) to 635, and TMSOTf-indnced cyclization gives 6-hydroxymethyl-3-phenyl-l,2,4-trioxane 636 (Scheme 181) °. Epoxides 638, which are characterized by geminal dimethyl substitnents, are obtained by m-CPBA oxidation of the (0-3,3-dimethyl-allyl)hydroperoxy acetals 637. While the strnctnral change in 638, as compared to epoxide 634, direct the acid-catalyzed cyclizations to the endo mode yielding the 7-membered... 

The authors proposed transition state models 532 and 533 to account for the diastereoselectivities observed in metal-catalyzed and m-CPBA oxidations, respectively (Fig. 8.16). The organization as well as directing role of the hydroxy group is... 

The preparation of a novel phosphonate containing 3,4-dihydro-2-H-pyrrole-1-oxide residue (216) has been reported. The synthesis of this solid and highly lipophilic spin trap is based on the addition of diethyl phosphite to pyrroline (217) and subsequent m-CPBA oxidation of phosphonate (218). (Scheme 59). The structure of the (218) was assigned using X-ray diffraction techniques. Its ability to react with different free radicals especially hydroxyl and superoxide was evaluated. ... 

Although the reaction of arynes with thiophenes as a route to naphthalenes leaves much to be desired, the reaction with thiophene-1,1 -dioxides is synthetically useful. An excess of benzyne precursor (benzenediazonium carboxylate) is used, and the solvent was refluxing 1,2-dichloroethane. Yields of naphthalenes are moderate and conversions are good. Thus 3-methylbenzyne and tetrachlorothiophene dioxide 296 gives naphthalene 297 in 65% yield (96% conversion). The thiophene dioxides may be prepared by m-CPBA oxidation of the corresponding thiophenes. 

In the leaves of G. elegans Benth., an Ab-oxide derivative of gelsemine was found (6). The stereochemistry of the quaternary nitrogen in 235 was determined to be the R configuration by H-NMR spectral comparison of two diastereomeric N-oxides prepared by wi-CPBA oxidation of gelsemine. 

Next, cermizine C (87) was converted into cermizine C N-oxide (88) by m-CPBA oxidation of 87. Synthetic 88 was identical in all respects with the new alkaloid isolated from L. cernuum by us, thereby establishing its structure [51]. 

Reaction of m-CPBA with the isoxazole (46) furnishes the nitrone (47) (eq 15). m-CPBA oxidation of (—)-isoxazole (48) and subsequent workup results in the formation of the (—)-cyclopentanone (49) (eq 16) the initially formed nitrone is hydrolyzed during workup. The oxaziridine (51) has been prepared by epoxidizing the sulfonimine (50) (eq 17). ... 

Oxidation of Allylic Iodides. m-CPBA oxidation of the primary allylic iodide (65) furnishes the secondary aUylic alcohol (66) (eq 26) this involves rearrangement of the iodoxy compound formed initially. 

The Boekelheide reaction was applied by the Nicolaou groups in the synthesis of a model system of the thiopeptide antibiotic thiostrepton (302). The tetrahydroquinoline 303 was converted into the A -oxide by /w-CPBA oxidation followed by treatment with TFAA and then hydrolysis to afford key intermediate alcohol 304 as a diastereomeric mixture. 

In 2010, the Sato group disclosed the synthesis of tetrodotoxin 86 starting from d-glucose, in which the Perrier carbocyclization of enol acetate 92 was employed for the construction of the cyclohexane core of tetrodotoxin. 4,6-O-Benzylidene derivative 99 was converted into pyranoside 93 possessing an exo-methylene group at C-3 (Scheme 12.47). m-CPBA oxidation of 93 stereoselectively provided epoxide 183. Alkaline hydrolysis of the epoxide in 183 followed by acetonide formation gave primary alcohol 184. Oxidation of 184 afforded aldehyde 185, which was converted into (Z)-enol acetate 92 by the action of acetic anhydride and potassium carbonate. When enol acetate 92 reacted with Hg(OAc)2, followed by NaCl treatment, the Perrier carbocyclization reaction successfully took place to afford a mixture of... 

Synthesis. First obtained and described by Bennett and Statham in 1931, racemic trans-1,3-dithiolane 1,3-dioxide can be conveniently prepared in a good yield (83%) by m-CPBA oxidation (eq 1) of 1,3-dithiolane in dichloromethane or ether, and with complete stereoselectivity (no meso adduct). 

Thiocarbonyl ylide 52, obtained by thermal treatment of bis(trime-thylsilylmethyl) sulfoxide 51, reacts, in a 1,3-dipolar cycloaddition reaction, with Cgo to afford a tetrahydrothiophene-fused C o derivative 53 (99TL1543). Subsequent treatment with m-CPBA oxidizes the substrates to afford the final sulfone 55. 

On the other hand, compound 245 was submitted to m-CPBA oxidation and the resulting N-oxide intermediate underwent a Cope reaction in acidic conditions to give N-hydroxypyrrolidine 246 in 77% yield (Scheme 41). The final steps of the synthesis were devoted to the construction of the intramolecular nitrone connection. For this purpose, appHcation of the Mukaiyama conditions generated in a regioselective fashion the nitrone intermediate, which collapsed via an intramolecular 1,3-dipolar cycloaddition to the required strained adduct. Final silyl deprotection furnished virosaine A (38) in 81% yield. 

Zhang et al. reported an efficient synthesis of piperidin-4-ones based on gold-catalyzed cascade process (Scheme 15) [61, 68]. One-pot sequential m-CPBA oxidation and gold-catalysis with Ph3PAuNTf2 led to an excellent yield of piperidin-4-one 39. This chemistry allowed facile preparation of 5-, 6-, and 7-membered ring-fused or spiro-piperidin-4-ones. Initially, Zhang et al. speculated that tertiary... 

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