Alkyl sulfmates

Cyclodextrins, toroidal molecules composed of 6, 7 and 8 D-glucose units, are now commercially available at reasonable cost. They form inclusion compounds with a variety of molecules and often differentially include sulfoxide enantiomers29,30. This property has been used to partially resolve some benzyl alkyl, phenyl alkyl and p-tolyl alkyl sulfoxides. The enantiomeric purities after one inclusion process ranged from 1.1 % for t-butyl p-tolyl sulfoxide to 14.5% for benzyl r-butyl sulfoxide. Repeating the process on methyl p-tolyl sulfoxide (10) increased its enantiomeric purity from 8.1% to 11.4% four recrystallizations raised the value to 71.5%. The use of cyclodextrins in asymmetric oxidations is discussed in Section II.C.l and in the resolution of sulfmate esters in Section II.B.l. 

Compounds 45 exhibit, in addition to sulfone-sulfmate rearrangements1 2 4-6 11, alkyl sulfone cleavages4,6,27, intramolecular Smiles-type rearrangements33 and extrusion of S023,5,29,30, an exceptional mode of remote group interaction which leads to the loss of... 

Electrochemical oxidation of disulfides and trapping of intermediately formed sulfmates by alkylation yields sulfones in good yields494. 

A major problem with the sulfoxide synthesis using menthyl sulfmates is its failure to produce optically pure dialkyl sulfoxides. The prerequisite menthyl alkanesulfinates are oils which have resisted separation into the individual epimers. The menthyl phenyl methanesulfmates are an exception the R epimer is crystalline . One solution to this problem, at least for preparing methyl alkyl sulfoxides, was achieved using cholesteryl methanesulfmates (27) . Both epimers were crystalline and could be separated by fractional crystallization, although in poor yield. Treatment of the epimers with n-propyl, n-butyl, isobutyl, p-tolyl and benzyl magnesium halides yielded the respective methyl alkyl sulfoxides (28) in greater than 95% e.e. and in 32 to 53% yields. 

The usual sulfone synthesis by displacement of halide by sulfmate is assumed to have a nucleophilic 8 2 mechanism However, in special cases of alkyl halides with additional, electron-withdrawing substituents a radical substitution pathway has been observed (equation 32). Correspondingly, substitutions under formation of sulfones take... 

Similarly, the reaction of the parent thiirane dioxide, the 2-chloro- and 2,3-cis-dimethylthiirane dioxides with either Grignard or alkyl lithium reagents, has been studied extensively. The fair-to-good yields of the sulfmates (62) obtained (48-82%), accompanied by ethylene (or the corresponding alkenes for substituted thiirane dioxide), have been interpreted in terms of initial nucleophilic attack of the base on the sulfur atom as depicted in equation 17 . 

The cleavage of alkyl aryl sulfones by sodium amalgam and alcohols probably proceeds also through the intermediacy of a radical anion, followed by splitting to the arylsulfmate anion and an alkyl radical. Both the sulfmate anion and the disproportionation products of the radical have been observed. 

Lange, E. A. Lin, Q. R, N. K., and Dooyema, C. C., Surfactants derived from 2-(2-hydroxiyphenyl)-benzene-sulfmate and alkyl-substituted derivatives. Patent No. US5973195. 

Sulfonates such as mesylates or tosylates are readily prepared from alcohols under mild conditions, and are therefore attractive alternatives to halides as electrophiles. Although sulfonates often undergo clean displacement by nucleophiles, alternative reaction pathways are accessible to these intermediates, which can lead to unexpected results. If the nucleophile used is strongly basic, metalation instead of displacement of the sulfonate can occur. Some potential reactions of such metalated sulfonates include fragmentation into sulfenes and alcoholates, or into sulfmates and carbonyl compounds, or self-alkylation (Scheme4.15). 

Finally, the sulfinates were transformed to o.p. sulfoxides by treatment with either Grignard or organolithium reagents. The presence of a free hydroxyl group in the sulfmate esters involves the use of two molar equivalents of the organometallic in THF at room temperature. Various dialkyl, alkyl aryl, and diaryl sulfoxides have been obtained in quantitative yield and in 100% ee (Table 12). 

Alkylation of fluonnated carboxylate [41] and sulfmate anions [42] occurs readily (equations 37 and 38)... 

Arylsulfmic acids are perfluoroalkylated under the conditions, but the yield IS low [77 (equation 70) The isolated product is an aryl perfluoroalkyl sulfone. The possible formation of a perfluoroalkyl aryl sulfmate intermediate, arising from an O-alkylation reachon, has not been discussed. 

Keywords alkyl halide, sodium phenyl sulfmate, alkylation, alumina, microwave irr iation, sulfone... 

The mixture of sodium phenyl sulfmate (6.566 g, 40 mmol) and neutral chromatographic alumina (20 g) was evaporated with a rotary evaporator under vacuum. The solid was dried 2 h at 110°C under vacuum. The alkyl halide (5 mmol) was absorbed onto sodium phenyl sulifmate on alumina (6.6 g, 1.52 mmol of sodium phenyl sulfmate). The mixture was irradiated by microwave (160 W, 5 min). After cooling at room temperature the mixture was extracted with acetonitrile. The product was recrystallized in ethanol after evaporation of solvent. 

A/-Alkyl-substituted nicotinic acid amides used as NAD models are selectively reduced in the 1,4-positions by Na2S204, e.g. 130 to 131. Initially, reaction with dithionite to give the base-stable sulfmate occurs ... 

Blending of a polymer carrying both tertiary amino and sulfmate groups with a polysulfonate under addition of a dihalogeno cross-Unker that alkylates both sulfmate and tertiary amino groups... 

Dependence of the membrane properties from type of cross-linker (different aromatic). A number of aromatic cross-linkers (Fig. 8.9) have been tested for their suitability for the sulfmate S-alkylation reaction. When determining the properties of the membranes, we could see that all cross-linkers were capable of... 

In addition to well-known nucleophilic behavior of thiolate anions, sulfmates are also active in substitution reactions. To this end, the conversion of a primary alkyl iodide into an alkyl sulfone has been accomplished by simply stirring the sodium sulfinate salt with the alkyl halide in DMF at room temperature (Scheme 5.20) [21]. While only a few examples were described, this work demonstrates the ability of sulfinate salts to participate in nucleophilic substitution reactions. 

---