Direct π‐Activation vs. O‐Activation in Halogen‐Bonding Catalysis

Abstract

AbstractHalogen bond donors had an increasing impact on catalysis in recent years, and their development is highly active. In particular, numerous iodine‐based halogen bond donors have been developed and used to promote various reactions through coordinating carbonyl groups, a ubiquitous mode of activation in catalysis. We now report computational data which strongly suggests that an alternative activation mode, through direct π‐complexation, is operative for unsaturated carbonyl substrates. Calculations also suggest that solvent polarity could have a clear impact on the preference of the mode of activation, raising the possibility of a mechanistic manifold switch through solvent variation. These findings could profoundly impact the development of the next generation of halogen‐bond donor catalysts.