O-alkylation d'amides A l'aide de sels d'alkyldiphenylsulfonium

O-Alkylation of amides and ureas was easily accomplished with alkyldiphenylsulphonium salts. These alkylating agents are readily available, often crystalline, and non-hygroscopic. They are somewhat less powerful than oxonium salts but are not limited to methyl and ethyl groups. The following order of reactivities was observed: PhCH2S+Ph2 > EtS+Ph2≈ Et2SO4 > MeS+Ph2. Benzylation proceeded under very mild conditions (room temperature). The counterion and solvent have no significant influence on the reaction rate. Sulphonium salts where the leaving group is a dialkyl sulphide are much less active as alkylating agents. New alkoxymethyleneiminium salts have been prepared in this way in yields above 70%.