Diphenyl sulfoxide, oxidation with

Precaution Dangerous fire hazard spontaneously flamm. in air vapor may flash back container explosion may occur under fire conditions explosive reaction with acetonitrile + diphenyl sulfoxide incompat. with strong acids, strong bases, strong oxidizing agents, alcohols, amines reacts violently with water hydrolyzed by water liberating acidic gas... 

No oxidizing agent is required for the sulfuric acid promoted cyclization of iV,iV-diphenyl-hydroxylamine to carbazole (13CB3304). The parallel conversion of diphenyl sulfoxide and diphenyl selenoxide to dibenzothiophene (23CB2275) and dibenzoselenophene (39CR(199)53l) is effected by treatment with sodamide. 

A conceptually new direct oxidative glycosylation with glycal donors, employing a reagent combination of triflic anhydride and diphenyl sulfoxide, has recently been reported by Gin [83], This new 3-glycosylation method works very well with hindered hydroxy nucleophiles, including sterically shielded carbohydrate hydroxy systems, and can be run on large scales. 

Likewise, pyridines such as methyl isonicotinate 1999 or quinolines are readily oxidized by BTSP 1949 in the presence of HOReOs in CH2CI2 to give, after 6 h at 24°C, 98% yield of, e.g., methyl isonicotinate N-oxide 2000 [174] (Scheme 12.49). The oxidation of diphenylsulfide with BTSP 1949 and triphenylphosphine dichloride in acetonitrile results, after 60 h at room temperature, in only 12% diphenyl sulfoxide 2001 and 88% recovered diphenyl sulfide [175] (Scheme 12.49), whereas thianthrene 5-oxide 2002 is oxidized by the peroxy-Mo complex 2003 to give 58% of a mixture of 2004 to 2007 in which the trans 5,10-thioxide 2005 predominates [176] (Scheme 12.50). 

The oxidation of sulfides to sulfoxides (1 eq. of oxidant) and sulfones (2 eq. of oxidant) is possible in the absence of a catalyst by employing the perhydrate prepared from hexafluoroacetone or 2-hydroperoxy-l,l,l-trifluoropropan-2-ol as reported by Ganeshpure and Adam (Scheme 99 f°. The reaction is highly chemoselective and sulfoxidation occurs in the presence of double bonds and amine functions, which were not oxidized. With one equivalent of the a-hydroxyhydroperoxide, diphenyl sulfide was selectively transformed to the sulfoxide in quantitative yield and with two equivalents of oxidant the corresponding sulfone was quantitatively obtained. 2-Hydroperoxy-l,l,l-fluoropropan-2-ol as an electrophilic oxidant oxidizes thianthrene-5-oxide almost exclusively to the corresponding cw-disulfoxide, although low conversions were observed (15%) (Scheme 99). Deprotonation of this oxidant with sodium carbonate in methanol leads to a peroxo anion, which is a nucleophilic oxidant and oxidizes thianthrene-5-oxide preferentially to the sulfone. 

The proposed mechanism of the oxidative cleavage of S-protecting groups by the chlorosilane/sulfoxide procedure is outlined in Scheme 8. 95 The first reaction is considered to be formation of the sulfonium cation 9 from diphenyl sulfoxide (7) and the oxygenophilic silyl compound 8. The formation of a sulfonium ion of this type is known and has been utilized for the reduction of sulfoxides. 97 Subsequent electrophilic attack of 9 on the sulfur atom of the S-protected cysteine residue leads to the formation of intermediate 10, whereby the nature of the silyl chloride employed should be the main factor that influences the electrophilicity of 9. The postulated intermediate 10 may then act as the electrophile and react with another S-protected cysteine residue to generate the disulfide 11 and the inert byproduct diphenyl sulfide (12). This final step is analogous to the reaction of a sulfenyl iodide as discussed in Section 6.1.1.2.1. 

Reaction of thiepine 26 with MCPBA in CH2CI2 gave sulfoxide 83 in 99% yield however, 83 did not react under various oxidizing conditions including mesitylenesulfonylhydroxylamine 84, which reacted with diphenyl sulfoxide to give aminated product (Equation 9) <20060BC2218>. 

Similarly, the /ra r-3-substituted-4-sulfenyl /3-sultams 126 can be synthesized as major products by treatment of 3-substituted /3-sultams with LDA followed by reaction with diphenyl disulfide. These are accompanied by the 3,4-air-isomers 127. It should be noted that these air-isomers can be converted to the trans-isomers by treatment with LDA in tetrahydrofuran (THF) at — 78 °C. Oxidation with /-chloroperbenzoic acid (MCPBA) provides /ra r-3-substituted-4-sulfinyl /3-sultams 128 as mixtures of stereoisomers at the sulfoxide moiety. This strategy was applied to obtain chiral 3-substituted-4-sulfinyl /3-sultams with a high diastereoselectivity (Scheme 38) <1998JOC8355>. 

The reaction of phenylmagnesium bromide with 1,3,2-dioxathioIane 2-oxide (16) gave 3.4-23% ethylene bromohydrin (131) and 42-60% diphenyl sulfoxide (132), depending on the conditions of the reaction. The bromohydrin (131) arises from a nucleophilic displacement at carbon by bromide ion, presumably via (129) and (130), while the sulfoxide (132) is formed by repeated attack of the Grignard reagent at sulfur (56JA454). 

Diphenyl sulfoxide and dimethyl sulfoxide are oxidized electrochemically to the coiresponding sulfones in acetonitrile and 1 M H2SO4, respectively. The product yields are enhanced the presence of transition metal salts or oxides of W, V, Mo or Se. In some cases sulfonic acid salts are formed with C—S cleavage. Sulfoxides react with oxygen under photochemical conditions to give sulfones in good yields. ... 

SAFETY PROFILE Moderately toxic by ingestion and inhalation. A corrosive irritant to skin, eyes, and mucous membranes. A very dangerous fire hazard when exposed to heat, flame, or by chemical reaction. May be ignited by spark or impact. Spontaneously flammable in air. Explosive reaction with acetonitrile + diphenyl sulfoxide. Will react with water or steam to produce heat and toxic and corrosive fumes. Can react vigorously with oxidizing materials. To fight fire, use CO2, dry chemical. When heated to decomposition it emits toxic fumes of CF. See also CHLOROSILANES. 

Sodium permanganate and, especially, osmium tetroxide oxidize sulfoxides to sulfones but do not oxidize sulfides [837]. When a mixture of equimolar amounts of diphenyl sulfide, diphenyl sulfoxide, and osmium tetroxide is refluxed in ether for 48 h, the sulfoxide is oxidized in 96% yield to the sulfone, whereas the sulfide is completely recovered [837], Certain unsaturated sulfoxides treated with a catalytic amount of osmium tetroxide and trimethylamine oxide as a reoxidant are not only oxidized to sulfones but also hydroxylated at the double bond. The sulfoxide group exerts a steric influence in the hydroxylation two stereoisomers of a sulfoxide yield, by syn hydroxylation, two different stereoisomeric diols (equation 580) [1102]. 

Oxidation of (80) with cyclohexyldimethylamine 7V-oxide and diphenyl sulfoxide yielded isomeric 1,2-oxasilatanes (81) and (82) regiospecifically, (Equations (33) and (34)) <88TL4747>. 

In an important contribution Liang et al. [92] examined the kinetics of the oxidation of diethyl sulfide in the presence of diphenyl sulfoxide and diphenyl sulfide, two molecules which react very inefficiently with 02(1Ag) themselves but undergo oxidation by some intermediate species to give the corresponding sulfone. They were able to show that, in methanol, both diphenyl sulfide... 

Thiophenol is oxidized with DCT or TBT to diphenyl disulfide. The latter reacts with DCT under more rigid conditions to give benzyl chloride. DCT oxidizes dibenzyl sulfide in methanol to dibenzyl sulfoxide (69ZC325) (Scheme 120). 

The oxidative fluorination of sulfur(IV) compounds such as diphenyl sulfoxide has been shown to occur under mild conditions with XeF2 and catalytic amounts of chloride ion. In the Ph2SO case the product is Ph2S(0)F2, which is formed in essentially quantitative yield within a few minutes. The chloride ion reacts with XeF2 to produce fluoride ion, and a mechanism is proposed that involves fluorosulfur(IV) anions and fluorosulfur(V) radicals (201). 

Singlet oxygen reactions. Dialkyl sulfides are oxidized to sulfoxides by singlet oxygen. Diphenyl sulfide is practically inert under the same conditions. However, if it is added to the photooxidation of a dialkyl sulfide, it is converted into diphenyl sulfoxide. The interpretation advanced by Foote and Peters is that diphenyl sulfide reacts readily with persulfoxides, formed in the reaction of alkyl sulfides with singlet oxygen ... 

Pyrolysis of sulfoxides provides a convenient method for introducing unsaturation at the position a- to carbonyl compounds. Formation of the enolate and reaction with dimethyl (or diphenyl) disulfide gives the a-methylthio (or phenylthio) derivative. Oxidation with a suitable oxidant, such as mCPBA or NaI04, gives the sulfoxide, which eliminates sulfenic acid on heating to give the a,(3-unsaturated carbonyl compound. For example, the methyl ester of a pheromone of queen honey bees was synthesized from methyl 9-oxodecanoate after initial protection of the ketone as the acetal (2.24). The -isomer usually predominates in reactions... 

Selective oxidation. Diphenyl sulfoxide refluxed 48 hrs. with OSO4 in ether diphenyl sulfone. Y 96%. - Diphenyl sulfide is unaffected under these conditions. H. B. Henbest and S. A. Khan, Chem. Commun. 1968, 1036 with Rh- and Ir-compounds cf. ibid. 1035. 

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