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The generation of thioesters through thioesterification of carboxylic acid has significant synthetic value given the easy availability of various carboxylic acids and the extensive application of thioesters. An economical and rapid thioester synthesis approach is still needed. Herein, we achieved thioesterification of carboxylic acids with valuable glycosyl thiol, aromatic and aliphatic thiols mediated by sulfonyl fluoride (SO2F2). The compatibility of numerous carboxylic acid substrates was tested, including (hetero)aromatic and aliphatic carboxylic acids and the reaction proceeded smoothly under mild conditions at good yields. Late‐stage modification of drug molecules rac‐Naproxen and Loxoprofen proved feasible. Besides, the gram‐scale reaction demonstrated the utility of this protocol. [ABSTRACT FROM AUTHOR]

Sulfonylaniline motif plays an important role in pharmaceutical sciences. Developed methods towards this structure are typically lack of good modifiability and stability. In this study, visible-light-mediated sulfonylation of aniline using sulfonyl fluoride as a modifiable and stable sulfonylation reagent is described. A variety of substituted sulfonylanilines were synthesized under mild reaction conditions with moderate to good efficiency. The example of late-stage sulfonylation highlighted the advantage of using sulfonyl fluoride as a sulfonylation reagent. In addition, the crucial influence of counterions on the photocatalyst observed in this system would inspire further research on the photochemistry of sulfonyl fluoride.

SuFEx chemistry is based on the unique reactivity of the sulfonyl fluoride group with a range of nucleophiles. Accordingly, sulfonyl fluorides label multiple nucleophilic amino acid residues, making these reagents popular in both chemical biology and medicinal chemistry applications. The reactivity of sulfonyl fluorides nominates this warhead chemotype as a candidate for an external, activation-free general labelling tag. Here, we report the synthesis and characterization of a small sulfonyl fluoride library that yielded the 3-carboxybenzenesulfonyl fluoride warhead for tagging tractable targets at nucleophilic residues. Based on these results, we propose that coupling diverse fragments to this warhead would result in a library of sulfonyl fluoride bits (SuFBits), available for screening against protein targets. SuFBits will label the target if it binds to the core fragment, which facilitates the identification of weak fragments by mass spectrometry. [ABSTRACT FROM AUTHOR]

Construction of chiral quaternary carbon sterocenters especially spirocycles in complex organic molecules is one of the great synthetic challenges. Using a quinine‐derived squaramide catalyst, the enantioselective Michael addition of 4‐amido‐5‐hydroxypyrazoles to ethylene sulfonyl fluoride (ESF) was developed. This method provides a facile strategy to access a series of structurally diverse pyrazolone derivatives with excellent yields and enantioselectivities. The introduction of quaternary carbon stereocenters and sulfonyl fluoride group leads to the valuable candidates for the drug discovery. Furthermore, the products could be transferred to the spirocyclic derivatives under mild reaction conditions without any loss of the enantioselectivities. [ABSTRACT FROM AUTHOR]

Sulfonyl fluorides have found widespread use in chemical biology and drug discovery. The development of synthetic methods for the introduction of the sulfonyl fluoride moiety is therefore of importance. Herein, a transition‐metal‐free radical 1,2‐difunctionalization of unactivated alkenes via FSO2‐radical addition with subsequent vicinal alkynylation to access β‐alkynyl‐fluorosulfonylalkanes is presented. Alkynyl sulfonyl fluorides are introduced as highly valuable bifunctional radical trapping reagents that also serve as FSO2‐radical precursors. The β‐alkynyl‐fluorosulfonylalkanes obtained in these transformations can be readily diversified by using SuFEx click chemistry to obtain sulfonates and sulfonamides. [ABSTRACT FROM AUTHOR]

Sulfonyl compounds have attracted considerable interest due to their extensive applications in drug discovery, agricultural, and material science. The access to the assembly of SO2‐containing compounds via the same oxidative‐state introduction of hypervalent sulfur has come to the fore in the recent years. Especially, the transition‐metal‐involved synthesis of hypervalent sulfur compounds is the most effective strategy since SO2 is easy to insert into the metal‐carbon bonds. This review discusses the application of the same oxidation‐state introduction of hypervalent sulfur strategy under the transition‐metal‐catalyzed conditions, and presents according to different metal catalysts and the synthesized diversity hypervalent sulfur‐containing compounds skeletons, including sulfonamides, sulfones, sulfinamides, sulfonyl acids and sulfonyl fluorides. [ABSTRACT FROM AUTHOR]

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Sulfonyl fluorides are valuable synthetic motifs which are currently of high interest due to the popularity of the sulfur (VI) fluoride exchange (SuFEx) click chemistry concept. Herein, we describe a flow chemistry approach to enable their synthesis through an electrochemical oxidative coupling of thiols and potassium fluoride. The reaction can be carried out at room temperature and atmospheric pressure and the yield of the targeted sulfonyl fluoride, by virtue of the short inter-electrode distance between a graphite anode and a stainless-steel cathode, reached up to 92% in only 5 min residence time compared to 6 to 36 h in batch. A diverse set of thiols (7 examples) was subsequently converted in flow. Finally, a fully telescoped process was developed which combines the electrochemical sulfonyl fluoride synthesis with a follow-up SuFEx reaction. [ABSTRACT FROM AUTHOR]

• New Cl/F exchange method for the preparation of sulfonyl fluorides was developed. • A stable derivative pyrrolidine-1-sulfinyl fluoride can be used a fluorination agent. • DFT calculations of chlorine/fluorine exchange reactions were studied. The reaction of (2S)-2-(difluoro(methoxy)methyl)pyrrolidine-1-sulfinyl fluoride with aryl, heteryl and alkyl sulfonyl chlorides provides a convenient synthetic route to sulfonyl fluorides. DFT calculations predict negative reaction energy values for the exchange reaction. The S-F bond energy is higher in the sulfonyl fluorides than that in sulfinyl fluorides. The reaction of (2S)-2-(difluoro(methoxy)methyl)pyrrolidine-1-sulfinyl fluoride with aryl, heteryl and alkyl sulfonyl chlorides provides convenient synthetic route to the sulfonyl fluorides. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract The importance of the sulfur-fluorine bond is starting to increase in modern medicinal chemistry literature. This is due to a better understanding of the stability and reactivity of this moiety depending on the various oxidation states of sulfur. Furthermore, several commercial reagents used for mild and selective fluorination of organic molecules are based on the known reactivity of S-F groups. In this review, we will show how these examples are translating into the 18F field, both for use as stable tags in finished radiopharmaceuticals and as mildly reactive fluoride-relay intermediates. Finally, we also discuss current opportunities where examples of non-radioactive S-F applications/chemistry may be translated into future 18F radiochemistry applications.

Fluorine‐18 is the most utilized radioisotope in positron emission tomography (PET), but the wide application of fluorine‐18 radiopharmaceuticals is hindered by its challenging labelling conditions. As such, many potentially important radiotracers remain underutilized. Herein, we describe the use of [18F]ethenesulfonyl fluoride (ESF) as a novel radiofluoride relay reagent that allows radiofluorination reactions to be performed in minimally equipped satellite nuclear medicine centres. [18F]ESF has a simple and reliable production route and can be stored on inert cartridges. The cartridges can then be shipped remotely and the trapped [18F]ESF can be liberated by simple solvent elution. We have tested 18 radiolabelling precursors, inclusive of model and clinically used structures, and most precursors have demonstrated comparable radiofluorination efficiencies to those obtained using a conventionally dried [18F]fluoride source. [ABSTRACT FROM AUTHOR]

Covalent inhibitors are widely used in drug discovery and chemical biology. Although covalent inhibitors are frequently designed to react with noncatalytic cysteines, many ligand binding sites lack an accessible cysteine. Here, we review recent advances in the chemical biology of lysine-targeted covalent inhibitors and chemoproteomic probes. By analyzing crystal structures of proteins bound to common metabolites and enzyme cofactors, we identify a large set of mostly unexplored lysines that are potentially targetable with covalent inhibitors. In addition, we describe mass spectrometry–based approaches for determining proteome-wide lysine ligandability and lysine-reactive chemoproteomic probes for assessing drug–target engagement. Finally, we discuss the design of amine-reactive inhibitors that form reversible covalent bonds with their protein targets. [ABSTRACT FROM AUTHOR]

Fluorine‐18 labelled prosthetic groups (PGs) are often necessary for radiolabelling sensitive biological molecules such as peptides and proteins. Several shortcomings, however, often diminish the final yield of radiotracer. In an attempt to provide higher yielding and operationally efficient tools for radiolabelling biological molecules, we describe herein the first radiochemical synthesis of [18F]ethenesulfonyl fluoride ([18F]ESF) and its Michael conjugation with amino acids and proteins. The synthesis of [18F]ESF was optimised using a microfluidic reactor under both carrier‐added (c.a.) and no‐carrier‐added (n.c.a.) conditions, affording, in a straightforward procedure, 30‐50% radiochemical yield (RCY) for c.a. [18F]ESF and 60‐70% RCY for n.c.a. [18F]ESF. The conjugation reactions were performed at room temperature using 10 mg/mL precursor in aqueous/organic solvent mixtures for 15 min. The radiochemical stability of the final conjugates was evaluated in injectable formulation and rat serum, and resulted strongly substrate dependent and generally poor in rat serum. Therefore, in this work we have optimised a straightforward synthesis of [18F]ESF and its Michael conjugation with model compounds, without requiring chromatographic purification. However, given the general low stability of the final products, further studies will be required for improving conjugate stability, before assessing the use of this PG for PET imaging. [ABSTRACT FROM AUTHOR]

Sulfonyl fluoride (SF) containing substances are currently attracting enormous attention among practitioners of both chemical biology and synthetic organic chemistry. The groups of Jones and Liskamp have demonstrated the potential of sulfonyl fluorides as selective covalent inhibitors in studies related to drug discovery and chemical biology, respectively, in the last few years. The Sharpless group has extended the repertoire of “click‐reactions” to those involving sulfonyl fluorides, that is, sulfur–fluoride exchange (SuFEx), a development that quickly triggered the interest in this functional group in the community of synthetic organic chemists. In this microreview, we aim to give an account of the synthetic chemistry surrounding sulfonyl fluoride containing substances from a historical perspective to present day developments. [ABSTRACT FROM AUTHOR]

Abstract: An efficient methodology has been developed for the two‐step synthesis of aliphatic sulfinate salts, sulfonamides, sulfonyl fluorides, and unsymmetrical sulfones on the basis of alkylation of a new versatile sulfonylating reagent. The new reagent is easily accessible in one step; the developed protocols are conducted under mild conditions and have a broad substrate scope. [ABSTRACT FROM AUTHOR]

The importance of the sulfur-fluorine bond is starting to increase in modern medicinal chemistry literature. This is due to a better understanding of the stability and reactivity of this moiety depending on the various oxidation states of sulfur. Furthermore, several commercial reagents used for mild and selective fluorination of organic molecules are based on the known reactivity of S-F groups. In this review, we will show how these examples are translating into the F field, both for use as stable tags in finished radiopharmaceuticals and as mildly reactive fluoride-relay intermediates. Finally, we also discuss current opportunities where examples of non-radioactive S-F applications/chemistry may be translated into future F radiochemistry applications. [ABSTRACT FROM AUTHOR]

Introduction: Covalent drug discovery has traditionally focused on targeting cysteine, but the amino acid is often absent in protein binding sites. This review makes the case to move beyond cysteine labeling using sulfur (VI) fluoride exchange (SuFEx) chemistry to expand the druggable proteome., Areas Covered: Recent advances in SuFEx medicinal chemistry and chemical biology are described, which have enabled the development of covalent chemical probes that site-selectively engage amino acid residues (including tyrosine, lysine, histidine, serine, and threonine) in binding pockets. Areas covered include chemoproteomic mapping of the targetable proteome, structure-based design of covalent inhibitors and molecular glues, metabolic stability profiling, and synthetic methodologies that have expedited the delivery of SuFEx modulators., Expert Opinion: Despite recent innovations in SuFEx medicinal chemistry, focused preclinical research is required to ensure the field moves from early chemical probe discovery to the delivery of transformational covalent drug candidates. The authors believe that covalent drug candidates designed to engage residues beyond cysteine using sulfonyl exchange warheads will likely enter clinical trials in the coming years.

Although the preparation of anomeric glycosylsulfonyl fluoride was unsuccessful, a tetra- O-acetylated C-glucosylpropanesulfonyl fluoride was synthesized starting from the corresponding thioacetate via sulfonate formation as the key intermediate. This sulfonyl fluoride was a bench-stable product that reacted promptly with primary and secondary alkylamines at 80 °C to give the corresponding sulfonamides in good yield. On the other hand, the same fluoride was inert toward arylamines whereas its precursor, the sulfonyl chloride, showed good reactivity. Another limitation of the acetylated sugar sulfonyl fluoride was its lack of reactivity with a multivalent aminated calixarene, this being due to acetyl transfer from the carbohydrate moiety to the amino groups of the scaffold. Fortunately, the tetra- O-benzylated C-glucosylpropanesulfonyl fluoride, prepared by the same reaction sequence employed for the synthesis of the acetylated analogue, reacted with the tetra-aminopropyl-calix[4]arene to afford the corresponding sulfonamide-linked sugar cluster in high isolated yield. A similar approach to the synthesis of calixarene-based iminosugar clusters was unsuccessful because 1-deoxynojirimycin sulfonyl fluoride derivatives could not be generated. However, a tetra-propylsulfonyl fluoride calixarene, obtained from the free-OH calix[4]arene through a three-step reaction sequence, underwent clean coupling with both C-glucosylpropylamine and N-aminopentyl-1-deoxy-deoxynojirimycin derivatives to give the corresponding tetravalent sugar and iminosugar clusters. This metal-free click reaction may constitute a valuable tool in the arsenal of ligation tools for the synthesis of multivalent carbohydrate architectures. [ABSTRACT FROM AUTHOR]

A protocol for the efficient conversion of sulfonyl fluorides into sulfonyl azides through Lewis base activation is described. The in situ generated sulfonyl azides are efficient diazo-transfer agents, affording diazo compounds and primary azides in excellent yields. [ABSTRACT FROM AUTHOR]

Small molecule ligands of cereblon (CRBN), a component of an E3 ubiquitin ligase complex, such as immunomodulatory drugs (IMiDs) or proteolysis targeting chimeras (PROTACs), induce new interactions between the E3 and a target protein that is subsequently polyubiquitinated and proteasomally degraded. The development of new degraders requires validation of CRBN-dependence and existing methods include the use of engineered CRBN knockout cell lines, or PROTACs directed to CRBN itself. Technical limitations of these approaches necessitate a simple and rapid pharmacological method of CRBN inhibition. We developed a sulfonyl fluoride covalent CRBN ligand based on the IMiD EM12 called EM12-SO 2 F that was designed to engage His353 on the surface of the IMiD binding site. EM12-SO 2 F does not act as a molecular glue degrader like other IMiDs, and instead serves as an inhibitor of such function by blocking the degrader binding site. We demonstrate utility of EM12-SO 2 F by inhibiting the degradation of the zinc-finger transcription factor and CRBN neosubstrate IKZF1 by the molecular glue degrader lenalidomide. Increasingly, libraries of degrader molecules are being screened phenotypically to identify starting points for hit elaboration, that simultaneously reveals new therapeutic targets amenable to degradation. Indeed, targeted protein degradation has become an exciting new therapeutic modality and EM12-SO 2 F augments the chemical biology toolbox that will advance this area of drug discovery research., Competing Interests: Conflicts of interest L.H.J serves on the SAB for, and holds equity in, Interline Therapeutics and Rapafusyn Pharmaceuticals, consults for Umbra Therapeutics, Ananke Therapeutics and Matchpoint Therapeutics, and holds equity in Jnana Therapeutics. The Center for Protein Degradation at DFCI receives research funding from Deerfield., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Abstract: The reaction of aromatic or benzylic disulfides with 2.5 equiv of Selectfluor™ in acetonitrile/water (10:1) at room temperature efficiently produced the corresponding thiosulfonates. Conversely, the reaction of disulfides with 6.5 equiv of Selectfluor™ or thiosulfonates with 4.5 equiv of Selectfluor™ in refluxing acetonitrile/water (10:1) provided sulfonyl fluorides in high yields. Accufluor™ and FP-T300™ are also effective in preparing sulfonyl fluorides from disulfides under the similar reaction conditions. Sulfonyl chlorides or sulfonyl bromides were effectively obtained from the reaction of disulfides with 6 equiv of either N-chlorosuccinimide or N-bromosuccinimide in acetonitrile/water (10:1) at room temperature. Some other electrophilic chlorinating or brominating reagents are also able to be used instead of N-chlorosuccinimide or N-bromosuccinimide for the syntheses of sulfonyl halides from disulfides. These reactions of disulfides with electrophilic halogenating reagents are convenient methods to prepare thiosulfonates and sulfonyl halides. [Copyright &y& Elsevier]

Abstract: The reaction of aromatic or benzylic disulfides with 2.5equiv of Selectfluor™ in acetonitrile/water (10:1) at room temperature efficiently produced the corresponding thiosulfonates. On the other hand, the reaction of disulfides with 6.5equiv of Selectfluor™ in refluxing acetonitrile/water (10:1) provided sulfonyl fluoride in high yields. [Copyright &y& Elsevier]

Various carboxylic acids were converted into acyl fluorides in excellent yields by treatment with trichloroacetonitrile, triphenylphosphine, and TBAF(t-BuOH)4 at room temperature. The reaction was applicable to the preparation of acid-sensitive amino acid fluorides without deprotection or rearrangement. [ABSTRACT FROM AUTHOR]

Abstract: 2-Methylprop-2-ene-1-sulfonyl fluorides can be easily prepared via the ene reaction of methallylsilanes and SO2. In the presence of a base, aldehydes and 2-methylprop-2-ene-1-sulfonyl fluorides give 1,3-(E) and (Z)-dienes. Their (Z)→(E) isomerization by classical means fails or leads to their polymerization. It is shown that SO2 can isomerize 1-aryl-3-methyl-1,3-dienes at low temperature, without formation of sulfolenes (cheletropic addition/elimination). Preliminary mechanistic studies suggest that SO2 adds to 1,3-dienes forming 1,4-diradical intermediates that are responsible for the (Z)→(E) isomerizations. [Copyright &y& Elsevier]