Alkylation of Several Nucleophiles with Alkylsulfonium Salts

Article abstract of DOI:10.1246/bcsj.63.2593

The reactions of dialkylphenylsulfonium salts (1) with several nucleophiles such as phenols, amine, enolate ion and thiolate ions, have been investigated.The relative reactivities of the alkyl groups of sulfonium salts for the phenolate ion (hard nucleophile) were as follows; Me:Et:i-Pr = 1.0:1.34:3.44.In the alkylation of the p-toluenethiolate ion (soft nucleophile) with 1, the opposite reactivity (Me:Et:i-Pr = 1.0:0.22:0.03) was found.When a sulfonium salt (1e) having an optically active (S)-s-butyl group was reacted with a phenolate ion, an optically active (R)-s-butyl phenyl ether was obtained with an inversion of the configuration at the chiral carbon atom.A reaction mechanism via a sulfurane intermediate is proposed for the alkylation of the phenolate ion with alkylsulfonium salts.The relative reactivities for the alkylation of several nucleophiles with dialkyl-phenylselenonium salts (12) were also investigated.