Drastic Enhancement of Activity in Iodane-Based α-Tosyloxylation of Ketones: Iodine(III) Does the Hypervalent Twist

A drastic enhancement in catalytic activity was observed by the introduction of steric hindrance ortho to the iodine atom of catalysts used for the α-tosyloxylation of ketones. Through structural analysis and density functional theory calculations, we explain the origin of this acceleration effect and show its significance through a first example of a chiral catalyst exploiting this feature.