Structurally Defined Molecular Hypervalent Iodine Catalysts for Intermolecular Enantioselective Reactions

Molecular structures of the most prominent chiral non‐racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen‐bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts was extended to the enantioselective dioxygenation of alkenes. A series of terminal styrenes are converted into the corresponding vicinal diacetoxylation products under mild conditions and provide the proof of principle for a truly intermolecular asymmetric alkene oxidation under iodine(I/III) catalysis. The “I”s have it: The enantioselective vicinal dioxygenation of styrene derivatives under mild conditions is catalyzed by chiral hypervalent iodine(III) compounds which are formed in situ from aryl iodines. Through hydrogen bonds, the ortho‐substituents give rise to a chiral helical environment around the iodine(III) center and thus enable high asymmetric induction.