Sulfur(VI) Fluoride Exchange (SuFEx): new developments and biological applications

Project Summary/Abstract The central goal of this project is to develop new sulfur fluoride exchange (SuFEx) reactions to construct small-molecule libraries containing the SVI-F motif and to explore their in vitro and in vivo functions. SuFEx is a new family of click chemistry transformations for generating diverse chemical structures bearing the SVI-F motif, such as -OSO2F (fluorosulfate), -SO2F (sulfonyl fluoride) and iminosulfur oxydifluorides. In the last seven years, we have established three versatile SulfurVI connectors: sulfuryl fluoride (SO2F2), ethenesulfonyl fluoride (ESF), and thionyl tetrafluoride (SOF4). SO2F2 selectively reacts with the – OH group of phenols to form aryl fluorosulfates, whereas SOF4 selectively reacts with primary amines to form iminosulfur oxydifluorides. Based on the aryl fluorosulfate chemistry, we invented extremely fast fluoride exchange reactions to introduce the fluorine-18 isotope into biologically active small-molecule radiotracers for positron emission tomography. By screening aryl fluorosulfate-based libraries, we discovered small-molecule covalent modifiers for Intracellular Lipid Binding Protein(s) and a platform for the late-stage drug functionalization. Building upon the above exciting discoveries, we will develop new transformations to expand the SuFEx transformation repertory and explore the feasibility of expanding fluoride exchange reactions to stable phosphorous(V) hubs. We will apply these new chemical transformations to construct screen libraries that can be used for rapid hit-to-lead optimization and for the development of covalent inhibitors and to construct stable 18F radiotracers for PET imaging.