Hydroamination reactions by metal triflates: Brønsted acid vs. metal catalysis?

Catalytic hydroamination reactions involving the addition of carboxamides (X = CO), carbamates (X = CO(2)) and sulfonamides (X = SO(2)) to unactivated C=C bonds are briefly reviewed. Development in this field of catalytic research is briefly charted, followed by a discussion of possible mechanisms, including arguments to support the operation of both metal and Brønsted acid catalysis in these systems. Future developments in the area are summarised.