Asymmetric stereodivergent catalysis achieved by means of a switchable asymmetric catalyst built on supramolecular helices

Despite recent developments on the design of dynamic catalysts, none of them have been exploited for the in-situ control of multiple stereogenic centers in a single molecular scaffold. We report herein that it is possible to select one major amongst four possible stereoisomers of an amino alcohol by means of a switchable asymmetric catalyst built on supramolecular helices. Hydrogen-bonded assemblies between a benzene-1,3,5-tricarboxamide (BTA) achiral phosphine ligand coordinated to copper and an enantiopure BTA monomer are engaged in a concomitant copper-hydride catalyzed hydrosilylation and hydroamination process, yielding mainly one of the possible stereoisomers in good yield. The nature of the product stereoisomer is related to the handedness of the helices and can thus be directed in a predictable way by the nature of the major enantiopure BTA present in the assemblies. Accordingly, a sequential reaction, during which the handedness of the supramolecular helices is switched in between the hydrosilylation and hydroamination steps, mainly yields the diastereoisomer that cannot be obtained in the aforementioned concomitant process. The strategy allows all stereoisomers to be obtained with similar selectivities. This work paves the way for the development of supramolecular helical catalysts as a platform to readily access molecules embedding several stereogenic centers.