Proline-Histidine Dipeptide: A Suitable Template for Generating Ion-Tagged Organocatalysts for the Asymmetric Aldol Reaction

Proline-histidine dipeptide laid the foundation for the construction of three new ion-tagged organocatalysts, utilising the imidazole moiety of histidine for generating the quaternary species. A brief comparative investigation of the catalysts in the enamine-mediated direct asymmetric aldol reaction brought out their contrasting features, particularly under aqueous conditions. The best among them was also utilised in preparing some derivatives and effecting a desymmetrisation.