Catalysis by tertiary chalcogenonium salts

The synthetic utility of onium salts is widely recognized in organic chemistry. Among the wide variety of onium salt compounds, quaternary ammonium and phosphonium salts are known as representative organocatalysts. Although the catalytic abilities of these group 15 onium compounds are well documented in the literature, organocatalysis by chalcogenonium salts as group 16 onium compounds has remained out of the spotlight until only recently. Several research groups, however, have noticed the catalytic potential of organo-chalcogenonium compounds based on the characteristics of group 16 elements in recent years. This mini-review introduces the high potential of tertiary chalcogenonium salts as effective organocatalysts for a variety of organic transformations.