Oxygen atoms sulfonate

Clearly, the oxygen atoms are important—the best anion-stabilizer is the sulfone, followed by the sulfoxide and then the sulfide. You could compare deprotonation of a sulfone with deprotonation of a ketone to give an enolate Chapter 21). Enolates have a planar carbon atom and the anion is mainly on the oxygen atom. Sulfone-stabilized carbanions have two oxygen atoms and the anionic centre is probably planar, with the negative charge in a p orbital midway between them. Carbanions next to sulfones are planar, while anions next to sulfoxides and sulfides are believed to be pyramidal (sp3 hybridized). 

Another deviation from the normal displacement reaction of primary tosylates occurs in nucleoside derivatives (39, 81) where cyclonucleosides and anhydronucleosides are formed by participation of a nitrogen atom (as in purine nucleosides) and oxygen atom (as in pyrimidine nucleosides ), respectively. Iodonucleosides can result from these reactions only if these cyclic compounds are prone to attack by iodide ion. Several new examples of unexpected reactions during the solvolysis of sulfonate esters in sugar derivatives have been recorded in the past few years (2, 4,5,7,15,44,62,63,94). 

For simple sulfones, the planar moment of the molecule is determined by the positions of the oxygen atoms, thus the knowledge of the O O distance may considerably aid the assignment of rotational transitions (see more details in Reference 5). 

Both the sulfone and the sulfoxide groups are characteristically electrophilic based on the increasing electropositivity of the sulfur atom in proportion to its oxidation state. Therefore, the nucleophilicity of these groups can be discussed only in terms of the nucleophilicity of either the trivalent sulfur atom, still having a pair of nonbonding electrons, or the oxygen atom in the sulfoxides. 

A long-range proton coupling, which was found to be transmitted by a sulfone group in thiolane dioxide systems292, is apparently facilitated by a nonbonding p-orbital on one of the sulfone oxygen atoms. This phenomenon is of interest for saturated cyclic systems. 

Meyers212 collected together several examples of the anomalous behavior of sulfones in which the group was close to the reaction center and interpreted these in terms of the negative direct field effect of the S02 oxygen atoms (cf. Meyers and colleagues141). 

Thiophene 1,1-dioxide (61) is too unstable to isolate and dimerizes with loss of S02 to give 3a, 7a-dihydrobenzothiophene 1,1-dioxide (172) in 34%113. However, alkyl-substituted thiophene 1,1-dioxides can serve as dienes in the Diels-Alder reaction, since the aromatic properties of the thiophene nucleus are lost completely and the n-electrons of the sulfur atom are used for forming the bond with oxygen. The sulfones 173-178 are found to react with two moles of maleic anhydride at elevated temperature to give bicyclic anhydrides114. Thus, at high reaction temperature, S02 is split off to give cyclohexadiene... 

Klemm and coworkers studied the spectra of several thienopyridine sulfones (72-78) and found that it is possible to distinguish by mass spectrometry between a sulfone function and a combination of two sulfoxide or JV-oxide functions in the same molecule . For instance, compound 77 forms 78 losing the 7V-oxygen atom, since except for the molecular ion their mass spectra are very similar. Compound 78 rearranges prior to fragmentation to the two possible cyclic sulfinates (80 and 81), which then fragment further by losing SO and CNO, respectively. 

Phenyl vinyl sulfones reacted with cyclohexanone enamines 332 to afford adducts which, upon hydrolysis, gave 2-(2-phenylsulfonyl)alkylcyclohexanone 333a . However, in the reaction with phenyl styryl sulfone, two products 333b and 334 were obtained by the nucleophilic attack at the and a-carbon atoms . Steric effects, electrostatic interactions between the nitrogen atom of the enamine and the oxygen atoms of the sulfone group, and medium effects contribute to the regioselectivity of the reaction. ... 

Similar to the thermal rearrangements discussed in the previous subsection, the base-catalyzed rearrangements of cyclic four-membered sulfones to five-membered sulfinates have also been reported. For example, Dodson and coworkers have observed the rearrangement of cis- and trans-2,4-diphenylthiethane 1,1 dioxides to cis- and trans-3, 5-diphenyl-1,2-oxathiolane (2,3)-cis-2-oxides, respectively (equation 35), on treatment with t-butoxymagnesium bromide, which is stereospecific with respect to the phenyl group but stereoselective with respect to the oxygen atoms on sulfur. 

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