Alkyl phenyl sulfides

Similar to nitrogen compounds, electron-rich sulfur compounds, such as the sulfides, with the lone pair of electrons on the sulfur atom, are oxidized to sulfoxides and, further, to sulfones by the H202/titanosilicate sytem (218,232, 233). Table XXXI (232) illustrates typical conversions and product selectivities for various sulfides for the reactions catalyzed by TS-1. Bulky sulfides such as alkyl, phenyl sulfides are relatively unreactive because of their steric exclusion from the pores of TS-1. Diphenyl sulfide could not be oxidized at all. As the diffusivity and, hence, the conversion of the sulfide decreases, the further oxidation of the primary product (sulfoxide) becomes more competitive, leading to increased formation of the corresponding sulfone (Table XXXI) ... 

Both the second and third processes in Scheme 13 can also be used for the functionalization of a-silylated alkyl phenyl sulfides [74] when oxidizing the latter in the presence of primary alcohols. First, the cleavage of the C—Si bond (equivalent to deprotonation) and then that of the S—C bond occurs to give... 

Scheme 17 Anodic substitution of a-silylated alkyl phenyl sulfides.

The classical preparation of alkyllithium compounds by reductive cleavage of alkyl phenyl sulfides with lithium naphthalene (stoichiometric version) was also carried out with the same electron carrier but under catalytic conditions (1-8%). When secondary alkyl phenyl sulfides 73 were allowed to react with lithium and a catalytic amount of naphthalene (8%) in THF at —40°C, secondary alkyllithium intermediates 74 were formed, which finally reacted successively with carbon dioxide and water, giving the expected carboxylic acids 75 (Scheme 30) °. 

The cleavage of alkyl phenyl sulfides by naphthalenelithium or a lithium ... 

Commercial polymers have been produced from methyl, ethyl, isopropyl, n-butyl, isotubtyl, t-butyl, stcaryl, benzyl and trimethylsilyl vinyl ethers. The polylmethyl vinyl ether) called PVM or Resyn is produced by the polymerization of the monomer by boron trifluoride in propane at —40°C in the presence of traces of an alkyl phenyl sulfide. The polymer may have isotactic, syndiotactic or stereoblock configurations depending on the solvent and catalyst used. 

Oxidation of alkyl phenyl sulfides by pyridinium bromochromate (PBC) is accelerated by electron-donating alkyl groups or aryl substituents, indicating an electron-deficient sulfur centre in the transition state this is accounted for in terms of rate-determining electrophilic oxygen attack from PBC to the sulfide in an. S -like process.7... 

M-1 s-1 alkyl phenyl selenides, aryl bromides, vinyl bromides, a-chloro esters, a-thiophenyl esters 104-102M 1 s-1 alkyl chlorides, alkyl phenyl sulfides, a-chloro and a-thiophenyl ethers. 

The first step in the reductive lithiation of alkyl phenyl sulfides (Screttas-Cohen process) consists of preparing the reducing reagent in stoichiometric amounts. Lithium naphthalenide, for example, is made from lithium and naphthalene. The sulfide is added drop wise to this reducing reagent. The mechanism of reduction corresponds step by step to the one outlined in Figure 17.44, except that the dissolved radical anion is the source of the electrons, as opposed... 

Wong s group32 investigated the chloroperoxidase-catalyzed oxidation of p-sub-stituted alkyl phenyl sulfides by hydrogen peroxide or racemic alkyl hydroperoxides as oxidant in aqueous buffer. Slow addition of H202 to the reaction mixture afforded nearly enantiopure sulfoxides (97-99% ee). Interestingly, when racemic alkyl hydroperoxides were used as oxidant, optically active alcohols and alkyl hydroperoxides were obtained (Scheme 4). 

The a-chloroalkyl phenyl sulfides are prepared by reaction of the corresponding alkyl bromide with sodium thiophenoxide to give an alkyl phenyl sulfide, which is then chlorinated by NCS. 

Na(Hg) used in excess with Na2HP04 in MeOH was particularly efficient, and presented fewer drawbacks. It was possible to perform reductive desulfonylations of sulfones in the presence of alkyl phenyl sulfides. This procedure tolerates ethers, a trimethylsilyl group, esters, - ketones, - isolat double and triple bonds, ketals, - amides and lactones. A few examples are given in Scheme 14. 

Oxidation of alkyl phenyl sulfides carried out in MeCN in absence of water affords sulfonium salts [93] ... 

The reactions of s- or t-alkyl phenyl sulfides by [CioHg] Li produce alkyl-Li as well as lithiated alkyldihydronaphthalenes, e.g. ... 

The alkyl phenyl sulfone precursors for the olefination may be prepared by the reaction of alkyl halides with sodium benzenethiolate, followed by oxidation of the alkyl phenyl sulfides formed with mCPBA. Alternatively, displacement of an alkyl bromide or iodide with the less nucleophilic sodium benzenesulfmate PhS02Na leads directly to the alkyl phenyl sulfone. 

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