Arenesulfenyl chlorides

The highly regio- and diastereoselective addition of an alkyl and an arylthio group to an olefinic double bond ( carbosulfenylation ) is achieved with arenesulfenyl chlorides and alkyl-chloro-titanium(IV) species (Reetz reagent, from R2Zn/TiCU 5 1 M. T. Reetz, 1987, 1989), Use of the more bulky 2,4,6-triisopropylbenzenesulfenyl chloride improves the yield of the highly versatile alkyl aryl sulfide products. 

An allylic sulfenate, like 199, is known to be in equilibrium with allylic sulfoxide, like 196, although its concentration is usually low . Various allylic sulfoxides can be prepared by treatment of allylic alcohols with arenesulfenyl chlorides . Evans and coworkers prepared various allylic alcohols by treating the corresponding allylic sulfoxides with trimethyl phosphite. For example, the carbanion from a cycloalkenyl sulfoxide 201 was readily alkylated at the a-position by treatment with alkyl halide. The resulting alkylated derivative 202 was then treated with trimethyl phosphite and 3-substituted cycloalkenol was obtained. Alkylation of acyclic allylic sulfoxide 204 gave... 

This approach allows one to functionalize the j3-C atom of AN. For this purpose, AN are initially subjected to double silylation to prepare BENAs, which are then coupled with various stabilized carbocations (512, 513), as well as with sulfenyl and episulfonium cations (514). Molecules containing good leaving groups (e.g., arenesulfenyl chlorides (514)) are used as sources (or precursors) of... 

Except for the addition products to 1,3-butadiene, the initial products isomerize slowly to the 1,4-adducts13. Although small amounts of these compounds have been found among the addition of 4-chlorobenzenesulfenyl chloride to methyl substituted 1,3-butadienes (equation 95), it was not possible to establish whether they were formed under kinetic control or resulted from isomerization of the initially formed adducts. Therefore it is generally reported that arenesulfenyl chlorides react with dienes to give exclusively 1,2-adducts. 

Reaction of methyl 3-(dimethylamino)-2-isocyanoacrylate (Ri = Me) with acyl chlorides gave 2-acyl-4-(dimethylaminomethylene)-5(477)-oxazolones 375. ° The same reaction with arenesulfenyl chlorides gave either 2-arylthio-4-(dimethylami-nomethylene)-5(477)-oxazolones 376 or an unsaturated 5(477)-oxazolone 377 containing an imidazole at C-2 depending on the substitution present in the arenesulfenyl chloride. Nitroarenesulfenyl chlorides favored 376. ° ° Selected examples of 372, 375, and 376 are shown in Table 7.33 (Fig. 7.44 Scheme 7.121). 

A mixture of perfluoro(2-methylpent-2-ene) (3.0 g, 10 mmol) and KF (0,23 g, 4 mmol) in dry DMF (5 mL) was stirred at 50-60 C for 3h under N. The color gradually turned deep yellow. Then arenesulfenyl chloride (2 mmol) was added dropwise and stirring was continued at 50-60 C for l-2h. After cooling, the mixture was diluted with FI O and extracted with EtjO (3x10 mL), The organic extract was washed with brine, dried (NajSOJ. and evaporated. The residual oil was chromatographed (silica gel, hexane) to give the aryl perfluoro(l,l-dimethylbutyl) sulfides. 

Smolyakova, IP, Smit, W A, Zal chenko, E A, Chizhov, O S, Shashkov, A S, Arenesulfenyl chloride adducts of glucal derivatives in the preparation of C-glucosides, Tetrahedron Lett., 34, 3047-3050, 1993. 

Alkane-and arenesulfenyl chlorides add to alkenes and alkynes thus, the addition of 2,4-dinitrobezenesulfenyl chloride (61) may be used to prepare solid derivatives of alkenes, e.g. the adduct (62) (Scheme 37). The Markownikoff addition of a sulfenyl chloride to an alkene is stereospecifically trans the adduct may be sequentially treated with a Lewis acid and a nucleophilic reagent to achieve the introduction of a new carbon-carbon bond (64) via the episulfenium ion intermediate (63) (Scheme 38). The procedure can also be applied to the synthesis of unsaturated sulfides, e.g. (65) (Scheme 39). 

Thioketones markedly differ from ketones in their reactions with electrophilic reagents.1,4 Ketones react chiefly at the a-carbon atom, whereas with thioketones the electrophile preferentially attacks the sulfur atom (thiophilic addition), leading to derivatives of the enethiol. The reactions are often performed in the presence of a base (Scheme 15). Thus, alkylation and acylation yield the enethiol derivatives (24) and (25). Similarly, reactions with an arenesulfenyl chloride, with carbon disulfide followed by an alkyl iodide, and with a carbonyl compound afford the compounds (26), (27) and (28), respectively (Scheme 15). The mechanisms of formation of the last two products are depicted in Scheme 16. 

To form a stable thiiranium ion, the counterion must be a very poor nucleophile to ensure that it will not react with the thiiranium ion. Despite claims to the contrary, the products of the reaction of these stable thiiranium ions with nucleophiles are similar to those formed in the addition reactions of alkene- and arenesulfenyl chlorides to alkenes in many respects. 

The nonstereospecific products are formed in both the reaction of stable thiiranium ions with nucleophiles and the addition of arenesulfenyl chlorides to alkenes. The reaction of the isomeric stable ions (158) and (159) with acetic acid at room temperature gives the same mixture of erythro-(160) and threo-( 161) products (Scheme 59) <75TL245i, 76IZV1318). Nonstereospecific products are also formed by the addition of 2,4-dinitrobenzenesulfenyl chloride to ( )- and (Z)-anisole <72JOC3086> and 4-methoxy-/ -deutereostyrene <84TL4983>. 

Only product (168) of the reaction with chloride ion is reported for the reaction of the stable ion (170) formed by the reaction of the epoxysulfide (169) with HC1 in acetonitrile (Scheme 61) <84IZV2652>. Thus, stable ions, like their counterparts in the addition reaction, react preferentially with the stronger nucleophile. But the reactions of stable ions are not necessarily good models for the intermediates in the addition of arenesulfenyl chlorides to alkenes, because in the addition of arenesulfenyl chlorides the ratio of products depends on the reaction conditions. Thus the reaction of thiiranium ion intermediate competes with that of an open -substituted alkyl carbocation <87CJC1945>. 

As far as the reactivity of polyenes is concerned, it is noteworthy that the stereochemistry of the addition of arenesulfenyl chloride to exocyclic tetraenes of type 87 depends on the substituent on the bridgehead carbon. The addition of arylsulfenyl chloride to the unsubstituted compound 87 proceeds with a high regio- and stereoselectivity . This tetraene adds 2-nitrobenzenesulfenyl chloride to give exclusively the unstable bisadduct 88, arising from a double 1,2-addition (equation 98) 20,121 regioselectivity of this... 

Dimethylamino-2-isocyanoacrylates (179) react with arenesulfenyl chlorides or acyl chlorides to furnish 4-dimethylaminoniethylene-5(4 -oxazolones (Scheme 87) <93JCR(S)i, 93JHC575). The structure of the acyl chloride product was secured through x-ray analysis. 

Arenesulfenyl chlorides can be prepared by chlorinating cleavage of aryl benzyl sulfides by means of sulfuryl chloride,651 and thiocarbonyl chlorides similarly from dithiocarboxylic acids and thionyl chloride.652... 

Benzenesulfenyl chloride in nitromethane added to 5 eqs. each of LiC104 and dimethyl sulfide in the same solvent, the precipitated LiCl removed, 0.5 eq. 2,3-dimethylbut-2-ene added at 0-5, and left for 10 h - dimethyl(2,3-dimethyl-2-butenyl)sulfonium perchlorate. Y ca. 90%. F.e. and arenesulfenyl chlorides s. I.V. Bodrikov et al., Zh. Org. Khim. 24, 1107-8 (1988). 

In a study on the reaction of arenesulfenyl chlorides with hydroxyl functions of ribonudeosides, the Pmoc residue was employed as a protective group for the 5 -hydroxy function in an adenosine derivative [628]. Reaction of 864 with Fmoc-Cl afforded the 5 -0-Fmoc-adenosine derivative 865 in 82% yield. 

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