Aryl thioethers

The conversion of allylic aryl thioethers ArSCH2CH=CH2 to 6>-allylic thiophenols... 

ALKYL-l-ALKYNES, 58, 1 ALKYL ARYL SULFIDES, 58,143 Alkyl aryl thioethers, 58,145 Alkylation, enolates, 56, 52 C-ALKYLATION, phase transfer catalysis... 

Sulfhydryl Compound Fluorobenzene Derivative Aryl Thioether Bond... 

Desulfuration.1 This complex as such or in combination with 2,2 -bipyridyl (bpy) or triphenylphosphine (a NiCRAL) can effect desulfuration of heteroarenes. aryl thioethers, dithioketals, sulfoxides, or sulfones in DME or THF at 63° in 1.5-30 hours. NiCRA is sufficient for aryl thioethers, dithioketals, but NiCRALs are more efficient for desulfuration of heteroarenes. Yields can be comparable with those obtained with Raney nickel. 

Alkyl aryl thioethers from thioiminium salts... 

Powdered KOH (0.17 g, 3 mmol) is added to the freshly prepared thioiminium halide [MeC(SR)NH2+Cl- or McC(SR)NMc2+C1 ] (3 mmol) and TEBA-C1 (0.12 g, 0.5 mmol) in CH2C12 (30 ml). The mixture is stirred at room temperature until the reaction is complete, as shown by TLC analysis. The organic phase is separated, washed with H20 (2 x 25 ml), dried (Na2S04), and the solvent evaporated under reduced pressure to yield the alkyl aryl thioether and the dialkyl disulphide, which can be separated by chromatography from silica. 

Activated aryl halides react with thiols [e.g. 4] to produce aryl thioethers and thioethers, derived from non-activated aryl halides, can be synthesized via the Cr(CO), complexes of the haloarenes [29] (Scheme 4.2, see also Chapter 2). 

A superior and relatively versatile procedure for the synthesis of unsymmetrical dialkyl thioethers, which avoids the unattractive direct use of thiols, utilizes the stable l-alkylthioethaniminium halides, which are readily obtained from thioacet-amidc [32] (Scheme 4.4). The reaction has also been used for the synthesis of alkyl aryl thioethers from activated aryl halides [33], but it cannot be used for the synthesis of cyclic thioethers, as polymeric sulphides are formed from a,co-dihaloalkanes. A similar sequence to that which leads to the thioethers has been used for the synthesis of S-alkyl thioesters [34] (see 4.1.26). 

Thiols have been linked to insoluble supports as acid-labile benzyl thioethers, as aryl thioethers, as S-carbamoyl derivatives, and as unsymmetrical disulfides (Table 3.37). Because thiols often undergo oxidative dimerization in air to yield symmetric... 

The API fluphenazine enanthate undergoes oxidation of a secondary aryl thioether to the resulting sulfoxide (Fig. 74) (112). 

The Leuckart Thiophenol Reaction allows the preparation of thiophenols and corresponding thioethers from anilines or their corresponding diazonium salts. The first step is the reaction of an aryl diazonium salt with a potassium alkyl xanthate to give an aryl xanthate, which affords an aryl mercaptan upon basic hydrolysis or an aryl thioether upon warming. 

Diketones react diastereoselectively with the dilithio compounds 475 obtained by the ortho and a-directed metallation of alkyl aryl thioethers and sulfones to give the fra r-thiochroman-3,4-diols and their 1,1-dioxides (Scheme 166) <1998S1098>. o-Bromophenyl sulfones 476 yield the 3,4-disubstituted thiochroman dioxide by a radical cyclization the trans isomer is the predominant or even exclusive product (Equation 160) <1995SL943>. 

Over MoS3, alkyl and aryl thioethers are hydrogenolyzed to give hydrocarbons, via... 

Mono- and difluorination of alkyl aryl thioethers under electrooxidative conditions also proceed when the phenyl ring is substituted by strongly electron-withdrawing groups, such as NO2, CN, SO Me, and S02Ph [116] (see Chapter 26). 

Leuckart thiophenol reaction. Decomposition of diazoxanthates by warming gently in faintly acidic cuprous media to the corresponding aryl xant-hates which produce aryl thiols on alkaline hydrolysis and aryl thioethers on warming. 

This procedure3 is an example of a simple and general method for preparation of primary and secondary dialkyl and alkyl aryl thioethers via alkylation of sodium sulfide or sodium alkyl- or arylthiolates with alkyl chlorides or bromides. The method is an... 

As with C-N couplings, C-0, C-S, and C-P bond formations also require a Cu(I) or Cu(II) source, a base, and solvent, with reaction temperatures ranging from 45 to 195°C. Typically the couplings see CoupUn are performed with aryl/vinyl boronic acids and aryl iodides (Scheme 3). Use of microwave technology allows for aryl thioether formation between aryl bromides and thiophenols. Inclusion of external ligands is not required for coupling, although several have... 

The addition of sulfur nucleophiles to alkynes is a less developed transformation. However, Yamamoto described the attack of the sulfur atom of aryl thioethers to afford benzothiophenes (equation 31). More recently, it has been showed that propargylic thioethers or thioacetals undergo migration to give carbenes that cyclize in hydroarylation processes and thiocarbamates that evolve by propargylic rearrangement. Thiosilanes can perform as both sulfur nucleophiles and silicon electrophiles in intramolecular reactions to afford benzothiophenes (equation 32). ... 

A series of S-substituted aminoalky-lamino ethanethiols, such as, 5 -2(omega-aminoalkylamino)ethyl alkyl/aryl thioethers, were screened for their protective efficacy against dermally applied sulfur mustard in female mice (Pathak et al. 2004). A number of compounds of this class, when administered orally, demonstrated significant protection against sulfur mustard. 

Buchwald reported a more cost-effective, high-yielding method for aryl thioether formation, including substrates for which the Palomo conditions were ineffective (2). Notably, this process employs a relatively low loading of an air-stable catalyst (Cul) and K2CO3 as the base. The simplicity of the reported conditions, the high degree of chemoselectivity and the broad substrate scope render this process an attractive choice for C-S bond formation [35]. 

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