Sulfide alkyl aryl alkene

The method employing the sequential alkylation and elimination of sulfoxides, reported above, has been successfully applied to the synthesis of dienes (Scheme 86, entry c), aryl alkenes and dienes (Scheme 47), vinyl sulfides, a,3-unsaturated sulfoxides, vinyl fluorides and vinyl chlorides (Scheme 96, entry a), and 1,1-dichloro-l-alkenes (Scheme 96, entry b). ... 

Alkyl(or aryl)sulfanylcyclopropanes are prepared by the addition of organosulfanylcarbene (carbenoid) to an alkene. This carbene is, in turn, generated via a-elimination of hydrogen chloride from the corresponding alkyl(aryl)chloromethyl sulfides using a base (Houben-Weyl, Vol.4/3, pp248-252 and Vol.E19b, pp 1690-1691 and 1693-1695). 

Potassium ert-butoxide, sodium hydride, butyllithium have all been used for this purpose. The alkyl(aryl)sulfanylcarbene (carbenoid) thus generated undergoes addition, often effectively, across the double bond of alkenes, enol ethers, ketene acetals and enamines. The use of chloromethyl phenyl sulfide, oxirane, tetraethylammonium bromide as a catalyst and an alkene gave phenylsulfanylcyclopropanes in rather low yield. For the synthesis of l,l-dimethyl-2-phenylsulfanylcyclopropane, see Houben-Weyl, Vol.4/3, p250 and of endoj exo-7-phenylsulfanylbicyclo[4.1.0]heptane, see Vol. E19b, pl691. 

Fluoroalkyl(aryl)iodonium salts are the most stable and practically important class of alkyl(aryl)iodonium derivatives. The application of such salts as electrophilic fiuoroalkylating reagents was reviewed in 1996 by Umemoto [1017]. Perfluoroalkyl(phenyl)iodonium trifiates (FITS reagents) 764 are efficient perfluoroalky-lating reagents toward various nucleophiUe substrates, sueh as arenes, carbanions, alkynes, alkenes, carbonyl compounds, amines, phosphines and sulfides [1017]. Scheme 3.300 shows several representative examples of electrophilic perfluoroalkylations using FITS reagents. 

Finally, but certainly not least, we note that the enzyme chloroperoxidase (CPO), catalyzes the highly enantioselective (>98% ee) sulfoxidation of a range of substituted thioanisoles [308]. In contrast to the epoxidation of alkenes, where turnover frequencies were low (see above), in the case of sulfoxidation of thioa-nisole a turnover frequency of around 16 s-1 and a total turnover number of 125000 could be observed. A selection of data is represented in Fig. 4.112. Besides aryl alkyl sulfides, also dialkylsulfides could be oxidized with reasonable enantioselectivities [27]. 

Reaction of aryl vinyl ethers, however, invariably gives mixtures of diazetidines and oxadiazines. The ratio is mainly dependent on the nature of the substituent on the phenyl group and, in part, on the nature of the alkyl group of the dialkyl diazenedicarboxylate and the solvent substituents which enhance the nucleophilicity of the alkene and the electrophilicity of the diazene, and polar solvents that favor a polar mechanism, result in concurrent formation of the diazetidine as the predominant product and vice versa15, l< Similarly, diazetidines 7 and oxadiazines 8 are formed in comparable yields in the reactions of vinyl sulfides with dimethyl diazenedicarboxylate, the ratio is principally dependent on the nature of the sulfur substituent (aryl, alkyl)17. 

Sulfides, or thioethers, are sulfur analogues of ethers, and like ethers they can be either symmetrical (R2S) or unsymmetrical (RSR1, where R and R are different). Sulfides can be prepared from alkyl halides by a Williamson-type synthesis with sodium hydrogen sulfide, sodium thiolate or sodium sulfide from alkyl or aryl halides via the Grignard reagent (11) from alkenes by radical-catalysed addition of thiols or by reduction of sulfoxides (Scheme 9).2b... 

This is rather an unexpected result, since sulfur is a weaker electron donor than oxygen and consequently vinyl sulfides should react slower compared to vinyl ethers if cyclopropanation is considered as a straightforward reaction of dichlorocarbene with an alkene double bond. Therefore, the formation of 2-alkyl(or aryl)sulfanyl-l,l-dichlorocyclopropanes is a multistep process, which starts with the generation of sulfonium ylides via the attack of carbene on the sulfur atom of the vinyl sulfide. The ylide thus formed undergoes 1,3-rearrangement and cyclization or reacts with another molecule of vinyl sulfide and then cyclizes. ... 

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