o-Benzenedisulfonimide and its chiral derivatives as Brønsted acid catalyst for one-pot three-component Strecker reaction. Synthetic and mechanistic aspects.

o-Benzenedisulfonimide (OBS) has efficiently catalysed the one-pot three-component reaction of ketones and aromatic amines with trimethylsilyl cianide (TMSCN) giving the corresponding α-amino nitriles in excellent yields (23 examples; average yield 85%). Reaction conditions were very simple, green and efficient. Theoretical calculations have allowed us to explain the mechanism of this reaction which has been found to take place in two phases; the first consists of the nucleophylic addition of the aniline to the ketone and the subsequent dehydration to an imine; the second one consists of the formal addition of CN- to the protonated imine. OBS acts in all steps of this mechanism. Without an acid catalyst, the reaction mechanism is more simple but barriers are sensibly higher. A chiral derivative of OBS was also used and gave fairly good results.