Impact of Host Flexibility on Selectivity in a Supramolecular Host-Catalyzed Enantioselective aza-Darzens Reaction.

A highly enantioselective aza-Darzens reaction (up to 99% ee) catalyzed by an enantiopure supramolecular host has been discovered. To understand the role of host structure on reaction outcome, nine new gallium(III)-based enantiopure supramolecular assemblies were prepared via substitution of the external chiral amide. Despite the distal nature of the substitution in these catalysts, changes in enantioselectivity (61 to 90% ee) in the aziridine product were observed.

A Nanovessel-Catalyzed Three-Component Aza-Darzens Reaction.

It has been previously demonstrated that nanovessels can be highly competent catalysts providing high rate accelerations and unique selectivity to the organic transformations which they mediate. However, for supramolecular assemblies to be considered a standard reagent in organic synthesis they must first demonstrate the ability to catalyze increasingly complex transformations. Herein, we report a three-component Aza-Darzens reaction that generates -phenylaziridines, catalyzed by a supramolecular host, that provides the stereoisomer opposite to the one generated in bulk solution ( vs ).