Bromonium salts: diaryl-λ3-bromanes as halogen-bonding organocatalysts.

Bromonium salts have been typically but infrequently used in various reactions as good leaving groups or as aryl or vinyl transfer reagents owing to their extremely high nucleofugality. Herein, we report the synthesis of novel, stable bromonium salts and their first catalytic application to the Michael reaction, with excellent product yield (up to 96%).