Sustainable Organocatalytic Processes to Access Alkyl SuFEx Click Hubs and Tetrasubstituted Carbon Centers: Potential Libraries for Multidisciplinary Applications

Abstract In this Account, we provide an overview of our recent achievements on sustainable organocatalysis. Our group has unveiled the effectiveness of specific organocatalysts under various environmentally benign conditions. We have found that N-heterocyclic carbene and phosphazene superbases exhibit favorable performances in bulk aqueous reaction environments. In addition, the use of organic superacid catalysts results in synergistic effects when hydrogen-bond donor catalysts are assembled in aqueous media. Moreover, we discovered that a neutral organic salt precatalyst can generate a potent silylium Lewis acid catalyst in situ, specifically under solvent-free conditions. These innovative, sustainable organocatalytic processes have successfully facilitated the conversion of raw starting materials into valuable compounds, including sulfur(VI) fluoride exchange (SuFEx) click hubs and tetrasubstituted carbon centers incorporating heteroatoms. 1 Introduction 2 Water-Accelerated N-Heterocyclic Carbene (NHC) Catalysis for β-Aminosulfonyl Fluorides 3 Water-Accelerated Phosphazene Superbase Catalysis for β-Sulfidosulfonyl Fluorides and γ-Geminal Dithioester-Incorporated Sulfonyl Fluorides 4 Water-Accelerated Synergistic Superacid Catalysis for α-Tertiary Amines 5 Solvent-, Metal-, and Purification-Free PPM (parts per million) Neutral Organic Salt Catalysis for Tertiary Cyanohydrin Derivatives 6 Conclusion