Of sulfides to sulfoxides and sulfones

Oxidation of Sulfides to Sulfoxides and Sulfones - Sodium Periodate-Silica... 

Rj = PhCH2 R2 = Ph Rj = Ph, n-C12ttz R2 = Me Scheme 6.34 Oxidation of sulfides to sulfoxides and sulfones by silica-supported sodium periodate. 

Oxidation reactions are not limited to those that occur at a carbon centre. The perfluorinated Ni(F-acac)2-benzene-CgFi7Br system described above was also active for the oxidation of sulfides to sulfoxides and sulfones [28], A sacrificial aldehyde is required as co-reductant, but the reaction may be tuned by changing the quantity of this aldehyde. If 1.6 equivalents of aldehyde are used, the sulfoxide is obtained, whereas higher quantities (5 equivalents) lead to sulfones. Fluorous-soluble transition metal porphyrin complexes also catalyse the oxidation of sulfides in the presence of oxygen and 2,2-dimethylpropanal [29],... 

SELECTIVE OXIDATION OF SULFIDES TO SULFOXIDES AND SULFONES USING... 

Butyl hypochlorite, 55 of phenols to quinones Benzoyl /-butyl nitroxide, 28 2,3-Dichloro-5,6-dicyano-l, 4-benzoqui-none, 104 Periodic acid, 238 of phosphorus compounds Dimethyldioxirane, 120 of selenium compounds Potassium permanganate, 258 of sulfides to sulfoxides and sulfones /-Butyl hydroperoxide-Dialkyl tar-trate-Titanium(IV) isopropoxide, 51 ra-Chloroperbenzoic acid, 76, 112 Dimethyldioxirane, 120 of thiols to sulfur compounds Trimethylsilyl chlorochromate, 327... 

Oxidation of sulfides to sulfoxides and sulfones was achieved in moderate to high yields with good selectivity by using 1 mol% of Fe203 as catalyst with molecular oxygen in the presence of isovaleraldehyde (Table 3.7) [145]. 

Selective oxidation of sulfides to sulfoxides and sulfones was achieved over sodium periodate (NaI04) on silica (20%), under solvent-free conditions to afford either sulfoxides or sulfones as desired (Scheme 5) [49]. 

The silica-supported benzisoselenazol-3(277)-one 117 (Scheme 42) was used as a heterogenous catalyst for hydrogen peroxide oxidation of sulfides to sulfoxides and sulfones, alkylarenes to the ketones and aromatic aldehydes to the arenecarboxylic acids. It exhibited appreciable activity and the results were similar to these when ebselen was a homogenous catalyst. It can be recovered from the reaction mixture simply, and reused <2004MI148>. 

Sodium perborate, NaBOa dlljO (mp 60 °C dec), is used for oxidations of primary aromatic amines to azo compounds [795] or nitro compounds [194] and of sulfides to sulfoxides and sulfones [794]. This reagent does not affect alcohols and only slightly affects alkenes [794]. 

The most important applications of peroxyacetic acid are the epoxi-dation [250, 251, 252, 254, 257, 258] and anti hydroxylation of double bonds [241, 252, the Dakin reaction of aldehydes [259, the Baeyer-Villiger reaction of ketones [148, 254, 258, 260, 261, 262] the oxidation of primary amines to nitroso [iJi] or nitrocompounds [253], of tertiary amines to amine oxides [i58, 263], of sulfides to sulfoxides and sulfones [264, 265], and of iodo compounds to iodoso or iodoxy compounds [266, 267] the degradation of alkynes [268] and diketones [269, 270, 271] to carboxylic acids and the oxidative opening of aromatic rings to aromatic dicarboxylic acids [256, 272, 271, 272,273, 274]. Occasionally, peroxyacetic acid is used for the dehydrogenation [275] and oxidation of aromatic compounds to quinones [249], of alcohols to ketones [276], of aldehyde acetals to carboxylic acids [277], and of lactams to imides [225,255]. The last two reactions are carried out in the presence of manganese salts. The oxidation of alcohols to ketones is catalyzed by chromium trioxide, and the role of peroxyacetic acid is to reoxidize the trivalent chromium [276]. 

The applications of ruthenium tetroxide range from the common types of oxidations, such as those of alkenes, alcohols, and aldehydes to carboxylic acids [701, 774, 939, 940] of secondary alcohols to ketones [701, 940, 941] of aldehydes to acids (in poor yields) [940] of aromatic hydrocarbons to quinones [942, 943] or acids [701, 774, 941] and of sulfides to sulfoxides and sulfones [942], to specific ones like the oxidation of acetylenes to vicinal dicarbonyl compounds [9JS], of ethers to esters [940], of cyclic imines to lactams [944], and of lactams to imides [940]. 

The oxidation of sulfides to sulfoxides and sulfones is achieved in a selective manner using MW irradiation under solvent-free conditions with desired selectivity to either sulfoxides or sulfones over sodium periodate (NaIO4) on silica (20%) (Scheme 8) A noteworthy feature of the protocol is its applicability to long chain fatty sulfides that are insoluble in most solvents and are consequently difficult to oxidize. Further, it circumvents the use of oxidants such as nitric acid, hydrogen peroxide, chromic acid, and peracids, which are conventionally used for the oxidation of sulfides to the corresponding sulfoxides and sulfones. 

MW protocols for oxidation-reduction reactions using immobilized reagents on solid supports have been extensively explored. The oxidation of sulfides to sulfoxides and sulfones was also developed under MW irradiation with good... 

Ozone is being promoted for use in the conversion of tertiary amines to amine oxides, of a-pinene to pinonic and pinic acids, of olefins to ozonides and these in turn to aldehydes and oxy-peroxides, of sulfides to sulfoxides and sulfones, and of various other organic substances. Such reactions are of practical interest in drug manufacture, and several drug companies are now commercially using ozone in their manufacturing operations, specifically in oxidation of sterols in hormone syntheses. 

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