The generation and electrophilic reactions of dimethyl sulphide cation radicals

Abstract

In anhydrous methylene chloride, nitrosomium tetrafluoroborate and dimethyl sulphide reacted to give a fairly stable red-brown solution at –70° which slowly decomposed at ca.–20° to afford trimethylsulphonium tetrafluoroborate. The red-brown solution reacted with olefins to afford 2-nitrosoalkyldimethylsulphonium salts and/or 1,2-bis-sulphonium salts, and with anisole to give p-methoxyphenyldimethylsulphonium salt. The reactions were interpreted as involving the electrophilic dimethyl sulphide cation radical as a reactive intermediate leading the attack on the π-bond systems. This is followed by radical combination or electron transfer–elimination to complete the addition and substitution pathways.