Organosulfur cation radicals arylation

With the advent of esr spectroscopy aromatic-antimony pentachloride precipitates were shown to contain the aromatic cation radical (Weissman et al., 1957), and this in turn accounted for the earlier discovery of paramagnetism in the salts obtained from reaction of aromatic amines with antimony pentachloride (Kainer and Hausser, 1933). Characterization of cation radicals in nitro-methane and nitrobenzene solutions of antimony pentachloride by visible spectroscopy soon followed. Eventually, by working with degassed solutions of antimony pentachloride in dichloromethane at —70° it was possible to obtain esr spectra of aromatic hydrocarbon cation radicals with extraordinarily well-resolved hyperfine patterns (Lewis and Singer, 1965, 1966). Similar success was obtained with alkyl aryl ether (Forbes and Sullivan, 1966), and organosulfur cation radicals in aluminum chloride-nitromethane solutions at —50° (Shine and Sullivan, 1968 Sullivan, 1968). In this work, resolution... 

One would not ordinarily regard ketones as nucleophiles. An Interesting reaction occurs, though, between dialkyl- and alkyl aryl ketones and organosulfur cation radicals. The products are 3-ketoalkylsulfonium salts, the stoichiometry of whose formation follows the usual pattern (eq. 21). A variety of ketones has been used (29-31), such as acetone, butanone, methyl isopropyl... 

Cation radicals react as electrophiles with aromatics. The scope of this type of substitution is not too well explored, though. Amination of aromatics with dialkylaminium radicals has been known for some time ( 2). In recent years the arylation of organosulfur cation radicals was discovered in our own laboratories (eq. 27) (33, 34). The reaction is limited in that the... 

We have more recently discovered a more versatile method of arylating heterocyclic organosulfur cation radicals, using organometallies R2Hg and R2Zn (eq. 30) (14). The reaction is even wider in scope in that dialkyImetals can be used too, which. 

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