Biocompatible SuFEx Cyclization Enables DNA-Encoded Macrocyclic Peptide Libraries for Drug Discovery

Direct introduction of R-SO2F moieties into proteins and protein-polymer conjugation using SuFEx chemistry

In this manuscript, we report practical, robust, and efficient conditions to synthesize a variety of unsymmetrical sulfamides via Sulfur(VI) Fluoride Exchange (SuFEx) click chemistry. This SuFEx strategy was subsequently harnessed to prepare a broad array of polysulfamides through polycondensation. The generality of the conditions allowed the synthesis of polymers with diverse architectures.

Sulfur (VI) fluoride exchange (SuFEx) reactions can be applied not only in organic click synthesis, but also in the preparation of functional main-chain polymers. In this work, four functional main-chain polysulfates (PNT-PS, NPNT-PS, PHF-PS, and TPE-PS) are synthesized in high yield using the SuFEx reaction at room temperature. The polysulfates exhibit satisfactory thermal stability and solution processability. They are used as the active layer for memory devices (ITO/PNT-PS/Al, ITO/NPNT-PS/Al, ITO/PHF-PS/Al, and ITO/TPE-PS/Al). I-V measurements show that ITO/PNT-PS/Al and ITO/NPNT-PS/Al exhibit stable flash-memory (write-read-erase) behavior, while ITO/PHF-PS/Al and ITO/TPE-PS/Al exhibit WORM (write once read many) behavior. Our studies provide a feasible and efficient synthetic methodology for the preparation of new memory materials.

Sulfur(VI)-fluoride exchange (SuFEx) chemistry, an all-encompassing term for substitution events that replace fluoride at an electrophilic sulfur(VI), enables the rapid and flexible assembly of linkages around a SVI core. Although a myriad of nucleophiles and applications works very well with the SuFEx concept, the electrophile design has remained largely SO2 -based. Here, we introduce S≡N-based fluorosulfur(VI) reagents to the realm of SuFEx chemistry. Thiazyl trifluoride (NSF3 ) gas is shown to serve as an excellent parent compound and SuFEx hub to efficiently synthesize mono- and disubstituted fluorothiazynes in an ex situ generation workflow. Gaseous NSF3 was evolved from commercial reagents in a nearly quantitative fashion at ambient conditions. Moreover, the mono-substituted thiazynes could be extended further as SuFEx handles and be engaged in the synthesis of unsymmetrically disubstituted thiazynes. These results provide valuable insights into the versatility of these understudied sulfur functionalities paving the way for future applications.

O‐sulfation is an important chemical code widely existing in bioactive molecules, but the scalable and facile synthesis of complex bioactive molecules carrying O‐sulfates remains challenging. Reported here is a general approach to O‐sulfation by the sulfur(VI) fluoride exchange (SuFEx) reaction between aryl fluorosulfates and silylated hydroxy groups. Efficient sulfate diester formation was achieved through systematic optimization of the electronic properties of aryl fluorosulfates. The versatility of this O‐sulfation strategy was demonstrated in the scalable syntheses of a variety of complex molecules carrying sulfate diesters at various positions, including monosaccharides, disaccharides, an amino acid, and a steroid. Selective hydrolytic and hydrogenolytic removal of the aryl masking groups from sulfate diesters yielded the corresponding O‐sulfate products in excellent yields. This strategy provides a powerful tool for the synthesis of O‐sulfate bioactive compounds.

Multidimensional detection of roxarsone via AIE-based sulfates

Targeted covalent inhibitors hold promise for drug discovery,particularlyfor kinases. Targeting the catalytic lysine of epidermal growth factorreceptor (EGFR) has attracted attention as a new strategy to overcomeresistance due to the emergence of C797S mutation. Sulfonyl fluoridederivatives able to inhibit EGFRL858R/T790M/C797S by sulfonylationof Lys745 have been reported. However, atomistic details of this processare still poorly understood. Here, we describe the mechanism of inhibitionof an innovative class of compounds that covalently engage the catalyticlysine of EGFR, through a sulfur(VI) fluoride exchange (SuFEx) process,with the help of hybrid quantum mechanics/molecular mechanics (QM/MM)and path collective variables (PCVs) approaches. Our simulations identifythe chemical determinants accounting for the irreversible activityof agents targeting Lys745 and provide hints for the further optimizationof sulfonyl fluoride agents.

mRNA display-enabled discovery of proximity-triggered covalent peptide–drug conjugates

Cyclic peptides hold great promise in drug discovery due to their conformational stability, proteolytic resistance, and ability to disrupt protein-protein interactions (PPIs). However, their therapeutic potential is often constrained by reversible binding, while covalent labeling strategies such as Sulfur(VI) Fluoride Exchange (SuFEx) have largely been limited to linear scaffolds. Here, we report a late-stage Pd(II)-catalyzed ortho-C(sp2)-H alkenylation of tyrosine that achieves directing-group-free late-stage peptide macrocyclization. This strategy preserves the phenolic side chain, which can subsequently be converted into an arylfluorosulfate for SuFEx-driven covalent labeling. The dual functionality of tyrosine thus enables the construction of macrocyclic scaffolds with enhanced conformational rigidity, intrinsic fluorescence, and covalent reactivity. As proof of concept, we synthesized a cyclic GnRH analogue (c-leuprolide) that exhibits superior antiproliferative activity compared with its linear counterpart. We further developed a covalent cyclic peptide-lysosome targeting chimera (CCP-TAC) that selectively degrades PD-L1, remodels the tumor immune microenvironment, and exhibits favorable biosafety in vivo. Together, these findings establish tyrosine-directed C─H functionalization as a versatile platform for multifunctional cyclic peptides, bridging synthetic methodology with therapeutic application and advancing peptide stapling, covalent labeling, and degrader technologies.

Herein, we describe the successful development of an azido-fluorosulfonylation reaction of alkenes under photoredox catalysis, which could allow the installation of the two "clickable" groups, -N3 and -SO2F, on a C-C double bond, with TMSN3 as the azide source. The utilization of the difunctionalization products is also demonstrated in the construction of a library of 1,2,3-triazolesulfonyl fluoride compounds as well as drug molecule ligation by merging copper-catalyzed azide-alkyne cycloaddition (CuAAC) and sulfur(VI) fluoride exchange (SuFEx), the two generations of click reactions. Mechanistic studies suggest a radical fluorosulfonylation/azidation mechanism and unveil FSO2N3 as a new and potential fluorosulfonyl radical precursor.

Herein, we report the preparation of 1,2,4-thiadiazinane 1,1-dioxides from reaction of β-aminoethane sulfonamides with dichloromethane, dibromomethane and formaldehyde as methylene donors. The β-aminoethane sulfonamides were obtained through sequential Michael addition of amines to α,β-unsaturated ethenesulfonyl fluorides followed by further DBU mediated sulfur(vi) fluoride exchange (SuFEx) reaction with amines at the S–F bond.

A rapid Brønsted superbase catalysis for highly functionalized sulfur(VI)-fluoride exchange (SuFEx) hubs bearing all-carbon quaternary centers was developed. Remarkable functional group tolerance toward esters and nitriles was achieved by Michael addition of cyanoacetate derivatives to ethenesulfonyl fluoride with low catalyst loadings (∼0.5 mol %) within a short reaction time (0.5-30 min). Gram-scalability, water tolerance, and compatibility in polymeric catalysis showcase its unique practicability. SuFEx click conjugations were demonstrated using various amines, including DNA-tethered biomolecules.

Allosteric regulation is a central mechanism for modulating biological functions and offers an attractive strategy in drug discovery, particularly for targets considered challenging or "undruggable." However, the discovery of allosteric inhibitors is hindered by poorly defined binding sites and the lack of effective screening approaches. Here, we present a dual DNA-encoded library (DEL) screening strategy that integrates reversible DEL and covalent DEL (CoDEL) technologies to identify novel allosteric inhibitors of the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp). Using this approach, we discovered the first covalent allosteric inhibitors of RdRp, which engage a previously uncharacterized pocket on the nsp8 subunit and form a covalent bond with Cys114. Subsequent SAR studies and biochemical assays confirmed the allosteric mechanism and elucidated structural determinants of activity. This work highlights the power of integrating reversible DEL screening with CoDEL screening for ligand discovery and establishes a generalizable strategy to identify covalent allosteric modulators for therapeutically important targets for therapy or active probe design.

Facile but effective synthesis and functionalization of polypeptides has long been a challenge, blocking the way to further explorations of their properties and potential applications. Here, we report the incorporation of sulfur(VI)‐fluoride exchange (SuFEx) moiety in amino acid N‐carboxyanhydrides, which grant the resulting polypeptides from ring‐opening polymerization the ability to utilize simple hydroxyl and amino groups on functional moieties of interest without the requirement for the introduction of preset conditions, such as reactive molecular anchors. We prepared series of polypeptides modified with sulfates or amidosulfonates (sulfamates), and importantly, we demonstrate that such linkages derived from SuFEx exhibit unique nature, which possibly benefits future biomaterial designs. In addition, the linkages can synergize with incorporated functionalizing moieties, demonstrated in a proof‐of‐concept example in which the sulfate‐linked, saccharide‐modified polypeptides showed outstanding antiviral activity and biocompatibility.

A novel trithiocarbonate reversible addition−fragmentation chain transfer (RAFT) reagent, 3‐azidopropyl (4‐[fluorosulfonyl]benzyl)trithiocarbonate (Az‐FSBCT), which has both clickable azidopropyl and sulfonyl fluoride moieties, was designed and synthesized. Using the RAFT agent Az‐FSBCT and triethylboron as an initiator, well‐defined poly(N‐vinylpyrrolidone) (PVP), in which the azide and sulfonyl fluoride groups are at the α and ω positions of the polymer chains, were prepared without prior deoxygenation at room temperature. Moreover, the possibilities for the construction of new functionalized polymers were also demonstrated by a “click” copper(I)‐catalyzed alkyne‐azide cycloaddition (CuAAC) and sulfur(VI)‐fluoride exchange (SuFEx) postreaction using these terminal functional PVPs.