Perfluorooxosulfate Salts as SOF4-Gas-Free Precursors to Multidimensional SuFEx Electrophiles.

Sulfur(VI) Fluoride Exchange (SuFEx) chemistry stands as a well-established method for swiftly constructing complex molecules in a modular fashion. An especially promising segment of this toolbox is reserved for multidimensional SuFEx hubs: three or more substituents pluggable into a singular SVI centre to make 'beyond-linear' clicked constructions. Sulfurimidoyl difluorides (RNSOF2) stand out as the prime example of this, however their preparation from the scarcely available thionyl tetrafluoride (SOF4) limits this chemistry to only a few laboratories with access to this gas. In this work, we identify silver pentafluorooxosulfate (AgOSF5) as a viable SuFEx hub with reactivity equal to SOF4. The AgF2-mediated oxidation of SOCl2 gives rise to the hexacoordinate AgOSF5 adduct, which in contact with primary amines produces the sulfurimidoyl fluorides in high yields. In addition, we have found this workflow to be fully extendable to the trifluoromethyl homologue, AgOSF4CF3, and we propose the use of AgOSF4X salts as a general route to azasulfur SuFEx electrophiles from commercial starting materials.

De-Risking S-F Bond Formation: A Gas Cylinder-Free Strategy to Access S(IV) and S(VI) Fluorinated Compounds.

The sulfur-fluorine partnership occupies a privileged position in fluorine chemistry given the functional versatility that it imparts to organic structures. Despite this, available methodologies to forge S-F bonds are limited compared to C-F bond formation. Here, we describe a synthetic protocol that selectively enables the oxidative halogenation of aliphatic, aromatic, and heteroaromatic thiols to their corresponding SF4 Cl, SO2 F and SF3 derivatives. Selective oxidation of thiols to either S(IV)-F or S(VI)-F compounds is achieved by employing bench-stable calcium hypochlorite as chlorine surrogate (CLOgen), in the presence of KF as fluoride source. Density functional theory (DFT) calculations provided insight into the mechanistic aspects of the transformation and rationalized the observed isomeric preference towards the SF4 Cl derivatives. Ultimately, this glovebox-free method selectively dispatches three classes of compounds upon reaction condition fine-tuning. Furthermore, first-in-class transformations are reported, including the preparation of aliphatic SF4 Cl intermediates, their transformation into aliphatic sulfur pentafluoride analogs, and post-functionalizations that allow accessing highly complex SF4 -bridged scaffolds.

Ex situ Generation of Thiazyl Trifluoride (NSF3 ) as a Gaseous SuFEx Hub.

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.

Chemistry of Pentafluorosulfanyl Derivatives and Related Analogs: From Synthesis to Applications.

Pentafluorosulfanyl (SF5 )-containing compounds and corresponding analogs are a highly valuable class of fluorine-containing building blocks owing to their unique properties. The reason for that is the set of peculiar and tremendously beneficial characteristics they can impart on molecules once introduced onto them. Despite this, their application in distinct scientific fields remains modest, given the extremely harsh reaction conditions needed to access such compounds. The recent synthetic approaches via S-F, and C-SF5 bond formation as well as the use of SF5 -containing building blocks embody a "stairway-to-heaven" loophole in the synthesis of otherwise-inaccessible chemical scaffolds only a few years ago. Herein, we report and evaluate the properties of the SF5 group and analogs, by summarizing synthetic methodologies available to access them as well as following applications in material science and medicinal chemistry since 2015.

DNA double-strand break repair pathway choice is directed by distinct MRE11 nuclease activities.

MRE11 within the MRE11-RAD50-NBS1 (MRN) complex acts in DNA double-strand break repair (DSBR), detection, and signaling; yet, how its endo- and exonuclease activities regulate DSBR by nonhomologous end-joining (NHEJ) versus homologous recombination (HR) remains enigmatic. Here, we employed structure-based design with a focused chemical library to discover specific MRE11 endo- or exonuclease inhibitors. With these inhibitors, we examined repair pathway choice at DSBs generated in G2 following radiation exposure. While nuclease inhibition impairs radiation-induced replication protein A (RPA) chromatin binding, suggesting diminished resection, the inhibitors surprisingly direct different repair outcomes. Endonuclease inhibition promotes NHEJ in lieu of HR, while exonuclease inhibition confers a repair defect. Collectively, the results describe nuclease-specific MRE11 inhibitors, define distinct nuclease roles in DSB repair, and support a mechanism whereby MRE11 endonuclease initiates resection, thereby licensing HR followed by MRE11 exonuclease and EXO1/BLM bidirectional resection toward and away from the DNA end, which commits to HR.

Lighting Up the Plasma Membrane: Development and Applications of Fluorescent Ligands for Transmembrane Proteins.

Despite the fact that transmembrane proteins represent the main therapeutic targets for decades, complete and in-depth knowledge about their biochemical and pharmacological profiling is not fully available. In this regard, target-tailored small-molecule fluorescent ligands are a viable approach to fill in the missing pieces of the puzzle. Such tools, coupled with the ability of high-precision optical techniques to image with an unprecedented resolution at a single-molecule level, helped unraveling many of the conundrums related to plasma proteins' life-cycle and druggability. Herein, we review the recent progress made during the last two decades in fluorescent ligand design and potential applications in fluorescence microscopy of voltage-gated ion channels, ligand-gated ion channels and G-coupled protein receptors.

Synthetic Approaches to Trifluoromethylselenolated Compounds.

The association of trifluoromethyl group to chalcogens gives new fluorinated substituents with specific properties, mainly in term of lipophilicity. The trifluoromethylselenyl group is the last of the series that has been studied and despite pioneering approaches in the late 1960s, CF3 Se chemistry has been scarcely developed over the last decades. Some modern and efficient methods to obtain trifluoromethylselenolated molecules have recently emerged. This Review describes the advancements that have been reported.

Benzyltrifluoromethyl (or Fluoroalkyl) Selenide: Reagent for Electrophilic Trifluoromethyl (or Fluoroalkyl) Selenolation.

Trifluoromethylseleno substituent (CF3Se) is an emerging group, but its direct introduction onto organic molecules is still quite limited and mainly restricted to nucleophilic methods. Herein, we describe a new approach to easily and safely perform electrophilic trifluoromethylselenolation starting from a simple and easily accessible reagent, namely, benzyltrifluoromethyl selenide. This strategy can be generalized to various fluoroalkylselanyl groups, even functionalized ones.

Direct Electrophilic (Benzenesulfonyl)Difluoromethylthiolation with a Shelf-Stable Reagent.

The (benzenesulfonyl)difluoromethylsulfanyl (PhSO2CF2S) group is a valuable substituent with specific properties which can provide access to new applications of fluoroalkylthiolated compounds. Direct introduction of this moiety can be performed by in an electrophilic manner by using a new shelf-stable reagent, namely a (benzenesulfonyl)difluoromethanesulfenamide. Furthermore, mild magnesium-mediated reduction of the PhSO2CF2S group leads to a facile synthesis of difluoromethylthiolated molecules and their deuterated analogs.

Novel Far-Red Fluorescent 1,4-Dihydropyridines for L-Type Calcium Channel Imaging.

Upregulation of L-type calcium channels (LTCCs) is implicated in a range of cardiovascular and neurological disorders. Therefore, the development of toolboxes that unlock fast imaging protocols in live cells is coveted. Herein, we report a library of first-in-class far-red small-molecule-based fluorescent ligands (FluoDiPines), able to target LTCCs. All fluorescent ligands were evaluated in whole-cell patch-clamp and live-cell Ca2+ imaging whereby FluoDiPine 6 was found to be the best candidate for live-cell fluorescence imaging. Low concentration of FluoDiPine 6 (50 nM) and a quick labeling protocol (5 min) are successfully applied to fixed and live cells to image LTCCs with good specificity.

An Extrusion Strategy for On-Demand SF5Cl Gas Generation from a Commercial Disulfide.

Herein we report a novel methodology for the ex situ generation of SF5Cl by employing 4,4'-dipyridyl disulfide as a safe commercial reagent, obviating the need for lecture bottles. The method is applicable to certain SF5Cl-involving transformations by using a two-chamber reactor. Moreover, easily applying SF5Cl in different solvents is rendered feasible, while avoiding the use of glovebox techniques. This report also suggests 1H-19F HOESY as a simple and fast stereochemistry indication for chloropentafluorosulfanylated olefins.

A Metal-Free Route to Heterocyclic Trifluoromethyl- and Fluoroalkylselenolated Molecules.

A metal-free methodology to easily synthesize various CF3Se-containing heterocyclic compounds has been developed through intramolecular ring closures of alkynes promoted with CF3SeCl. Moreover, this strategy has also been extended to other fluoroalkylselenyl groups.