Oxidation peracid

Peracid oxidation of imines is the most general synthesis of oxaziranes (Section 5.08.4.1.1). Other peroxides and metal catalysis have also been employed. 

Even the trivial decomposition of oxaziridines may have some importance. In the oxidation of s-alkylamines to ketones conversion to the Schiff base of 2-pyridinealdehyde was proposed, followed by peracid oxidation to the oxaziridine (295). Decomposition by alkali yields the ketone added excess acetone suppresses condensation of pyridinealdehyde with dialkyl ketone (75AJC2547). 

Acyl-lO.l l-epoxy-5//-dibenz[6,/]azepines 11 are obtained in moderate yields by oxidation of 5-acyl-5//-dibenz[A,/]azepines 10 with 3-chloroperoxybenzoic acid124 197,219 (see also Section 3.2.2.2.2.). As expected, peracid oxidation of 10-(alkylsulfanyl)-5//-dibenz[A,/]azepincs occurs at sulfur rather than at the CIO —Cl 1 double bond.213... 

Peracetic acid can be used to preferentially oxidize sulphoxides to sulphones in the presence of hydroxyl groups41, whilst attempted peracid oxidation of 2,6-diiodoaryl sulphoxides was not successful42. 

The reaction mechanism for the peracid oxidation of thiosulphinates is perhaps more complex than described above. A study of the low-temperature ( — 40 °C) peracetic acid oxidation of 2-methyl-2-propyl 2-methyl-2-propanethiosulphinate gave two products as shown in equation (81)196. During the reaction the a-disulphoxide was apparently detected by NMR spectroscopy. 

Once the active Co catalyst has been formed by peracid oxidation of Co the next step is determined by the relative rates of reaction of this species with other species present in the solution, i.e. Mn, Br" and the substrate, and its rearrangement to the much less reactive Co . As can be seen from these data (Fig. 15), the relative rates of reaction of Co with Mn Br" and p-xylene are 940, 84 and 0.03, compared to 1 for the conversion of Co to Co (ref. 9). This means that in a mixture containing Co , Mn Br" and p-xylene, > 90% of Co reacts with Mn to afford Mn and that there is no reaction of Co with the p-xylene substrate. 

In 1960, Montanari and Balenovic and their coworkers described independently the first asymmetric oxidation of sulfides with optically active peracids. However, the sulphoxides were formed in this asymmetric reaction (equation 130) with low optical purities, generally not higher than 10%. The extensive studies of Montanari and his group on peracid oxidation indicated that the chirality of the predominantly formed sulphoxide enantiomer depends on the absolute configuration of the peracid used. According to Montanari the stereoselectivity of the sulphide oxidation is determined by the balance between one transition state (a) and a more hindered transition state (b) in which the groups and at sulphur face the moderately and least hindered regions of the peracid,... 

To account for stereochemical results for the epoxidation of allyl alcohols, a slightly different intermediate has been proposed as shown in Fig. 6.9.16 The authors propose an intermediate (A) analogous to the intermediate in peracid oxidations. A small molecule of alcohol or water is coordinated to Ti with deprotonation and another is coordinatively ligated to Ti without deprotonation to achieve a pentacoordinated ligand sphere. During epoxidation, the allyl alcohol substrate is held in position by a hydrogen bond. 

Epoxidation of the 3,4-dihydrodiol with m-chloroperbenzoic acid afforded stereospecifically the corresponding anti diol epoxide (74). Peracid oxidation of the bay region 1,2-dihydrodiol gave a mixture of the anti and syn diol epoxide diastereomers. Assignment of the major isomer as syn was made through analysis of the NMR spectra of the acetates of the tetraols formed on hydrolysis of the individual diol epoxides (42). Peracid oxidation of the 10,11-dihydrodiol is reported to yield the corresponding anti diol epoxide (12). However, it is likely for steric reasons that the syn isomer is also formed. 

Alkylsulfonic peracids oxidize olefins to epoxides. The formed sulfonic acid reacts with epoxide to form diols and esters. The yields of epoxides in the reactions of oxidation of two cycloolefins are given in Table 12.4. 

One can expect that epoxidation occurs as electrophilic reaction. Peracid oxidizes olefin in two forms monomeric and dimeric. The following scheme of epoxidation was proposed [42] ... 

Sulfonic peracids oxidize ketones to lactones. The yields of the oxidation products are listed in Table 12.6. 

Ring A diosterols.3 The ring A diosterols (3 and 4) of triterpenes can be prepared from the A2-alkene (1) by osmylation to form the two possible cis-diols (2), which on Swern oxidation give the a-diketone (3). The same diketone is also obtained by Swern oxidation of the 2(3,3a-diol, the product of peracid oxidation followed by acid cleavage. The diketone 3 rearranges to the more stable diosphenol (4) in the presence of base. 

The last synthesis to evolve which is due to Ito and his coworkers is interesting in that it relies on a stereospecific skeletal rearrangement of a bicyclo[2.2.2]octane system which in turn was prepared by Diels-Alder methodology (Scheme XLVIII) Heating of a toluene solution of cyclopentene 1,2-dicarboxylic anhydride and 4-methylcyclohexa-l,4-dienyl methyl ether in the presence of a catalytic quantity of p-toluenesulfonic acid afforded 589. Demethylation was followed by reduction and cyclization to sulfide 590. Desulfurization set the stage for peracid oxidation and arrival at 591. Chromatography of this intermediate on alumina induced isomerization to keto alcohol 592. Jones oxidation afforded diketone 593 which had earlier been transformed into gymnomitrol. 

Peracid oxidation of the D-homo-oestrone derivative (59) gave the C-ring aromatic compound (60). ° Mono- or tri-formylation with DMF-POCI3 of 17-methylene-steroids led to the unsaturated aldehydes (61) or the dimethylamino-bisaldehydes (62) which were readily converted with NHa-EtOH into the heterocycles (63). 14-Azidopregnanes are available from the reactions of A -... 

Thietes can be prepared by elimination from appropriately substituted thietanes. 2,4-Diarylthiete 1,1-dioxides (146 and 147) were produced in good yields by peracid oxidation and intramolecular amine oxide elimination of 3-dimethylaminothietane 1,1-dioxides (Eq. 23). 

The peracid oxidation of 2//-imidazoles to iV-oxides and Af,iV -dioxides has been discussed (Section II,E) both 92 and 99 under similar conditions give imidazolinones 124. ... 

Guaifensin Glycerol mono(2-methoxyphenyl) ether Peracid oxidation of phenol, partial A-methylation, nucelophilic displacement of glycidol... 

Decalactone can be prepared by peracid oxidation of 2-pentylcyclopentanone. It is used in perfumes and for cream and butter flavorings. 

There are only a few reports concerning the peracid oxidation of azepines. 30% Hydrogen peroxide oxidizes TV-alkyl-6,7-dihydro-5iT-dibenz[c,e]azepines to their TV-oxides (75ZN(B)926), whereas MCPBA has been used to prepare the 3H-2-benzazepine TV-oxide (88) (74JOC2031). TV-Oxidation of 2,3,4,5-tetrahydro-lH-l-benzazepine with MCPBA is accompanied by dehydrogenation to the 4,5-dihydro TV-oxide (89) (79JOC4213). 

Fukuto, J. M., Stuehr, D. J., Feldman, P. L., Bova, M. P., and Wong, P. (1993). Peracid oxidation of an N-hydroxyguanidine compound A chemical model for the oxidation of N-omega-hydroxyl-L-arginine by nitric oxide synthase. J. Med. Chem. 36, 2666-2670. 

In the aliphatic series, the peracid oxidation appears to be limited to i-alkyl primary amines or alicyclic amines [39]. 

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