Arylsulfonyl group

The accelerative effect of London forces of attraction between a nucleophile and nearby substituents has been investigated in quinoline and benzene derivatives by Bunnett and co-workers, ii7b, 307 In 2-, 4-, and 6-arylsulfonyl-3-nitrochlorobenzene, Loudon and Shulman found that arylmercaptide ion, presumably through this effect, displaced the arylsulfonyl group while methoxide or ammonia displaced the nitro or chloro group. 

The steric requirements of the enhanced interaction between arylsulfinyl or arylsulfonyl groups and the benzene ring in bis(4-hydroxyphenyl)sulfoxides or sulfones were examined by Oae and colleagues through the introduction of methyl groups in two or four of the positions ortho to SO or S02. As in the work described earlier for S02Me, effective values for the combined influence of the substituents o (obs.) were determined and compared with o (calc.) computed on the basis of strict additivity of substituent effects on the dissociation... 

Of the studies which bear more particularly on electronic effects we mention first a study of the base-catalyzed H-D exchange in the 3-arylsulfonylbicyclo[2.2.1]hept-5-ene-2-carboxylic acids, cis (33), (35) and trans (34), and of the base-catalyzed inversion of the arylsulfonyl group in cis compounds (33) and (35)191. R comprised several meta- or para-... 

Note When attached to an atom other than carbon, alkyl- or arylsulfonyl groups are usually known as alkane- or arenesulfonyl groups (lUPAC Rule C 21)1076 considerd as acyl-type derivatives rather than sulfones. 

The derivatives bearing the arylsulfonyl groups at the 3- position of the ring proved to be more potent than the 4-arylsulfonyl substituted isomers, and the pair of isomeric phenyl-phenylsulfonylfuroxans (43a,b R=Q,I13) was more potent than the cor-... 

Thus, the progressive accumulation of alkyl and/or arylsulfonyl groups onto a benzene ring (in the aromatic polysulfones (27)-(31)) led to an increasing stabilization of the corresponding anion radicals. 

The synthesis of 4-alkyl thioketones is possible by exploiting the stabilizing effect of a sulfur atom upon an adjacent carbanionic center. Ambident allylic anions react so that conjugate addition proceeds exclusively with the a-carbon of the nucleophile,129 243 244 as illustrated in equation (S3) 245 arylsulfinyl and arylsulfonyl groups normally246 behave similarly.247-249 Sulfur-stabilized vinylic carbanions can be prepared and function as Michael donors in difunctionalization sequences.250... 

As evidenced by the treatment of three (Z)-(/l-arylsulfonyl-l-decenyl)phenyliodonium fluoroborates with triethylamine, the presence of electronically diverse substituents (H,p-N02, / -MeO) in the arylsulfonyl groups appears to have little impact on their migratory aptitudes (equation 239)32. Indeed, among six [(/1-alkyl-/l-arylsulfonyl)vinyl]iodonium salts that have been investigated, the cyclopentene/alkyne ratios show little variability (i.e. 70 30 to 80 20)32. Finally, the presence of an appropriately placed alcohol function in the side chain of a (/l-sulfonylvinyl)iodonium salt has been shown to completely suppress migration in favor of insertion (equation 240)32. 

Displacement of a nitro group has also been observed. 4,7-Bis(arylsulfonyl)benzofuroxans are formed from (56 n = 1) and arylsulfinates furthermore, the arylsulfonyl groups in the product may themselves be displaced by other nucleophiles. 

The next section will be concerned with the selective removal of arylsulfonyl groups in AMosylamines by a PET process. 

Since its introduction in 1986315, the 2-(trimethylsilyl)ethylsuifonyl group has been widely adopted in alkaloid, carbohydrate and amino acid chemistry, it is every bit as stable as the arylsulfonyl groups discussed above it is impervious to the ravages of trifluoroacetic add, hot 6 M HC1, trifluoroborane etherate, or 40% HF in ethanol. Nevertheless, under very specific non-reductive conditions, it can be cleaved. The link with 2-(trimethylsilyl)ethyl esters, 2-(trimethylsilyl)ethoxycarbon-y t derivatives, and 2-(thmethylsilyl)ethoxymethyl ethers hardly needs comment. 

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