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.

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 SF4Cl, SO2F 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. DFT calculations provided insight into the mechanistic aspects of the transformation and rationalized the observed isomeric preference towards the SF4Cl derivatives. Ultimately, this glovebox-free method selectively dispatches three classes of compounds upon reaction condition finetuning. Furthermore, first-in-class transformations are reported, including the preparation of aliphatic SF4Cl intermediates, their transformation into aliphatic sulfur pentafluoride analogs, and posttransformations that allow accessing highly complex SF4-bridged scaffolds.

The 1,4-dihydropyridine is a ubiquitous scaffold employed not only in medicinal chemistry but also in organic synthesis, given its ability to act as a hydrogen transfer reagent, thus emulating NAD(P)H reducing agents. In this work, we describe the synthesis of 3-methyl 5-{3-[(4-methylbenzenesulfonyl)oxy]propyl} 4-(2,3-dichlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate as scaffold, which enables downstream derivatization towards new 1,4-dihydropyridine molecules. Inspired by the literature, a new two-step synthesis was planned that involved: (i) synthesis of a silylated 1,4-dihydropyridine derivative and (ii) deprotection and tosylation in one step using tosyl fluoride.

Receptorflix would ideally enable researchers to visualize any already‐targeted transmembrane receptor at the cell's surface. Tailor‐made fluorescent ligands accessed by coupling pharmacophores to organic fluorescent dyes are successfully employed to image GPCRs, LGICs, and VGICs. Recent advances in fluorescence microscopy and progress in dye synthesis enable their use in distinct techniques and model organisms. Read more about the literature of the last 25 years on the topic, including fluorescent ligand design and subsequent use in fluorescence imaging techniques to study the three most common classes of transmembrane receptors in the Review by S. Munck and E. Ismalaj et al. on 8605 ff.

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 SF4Cl, SO2F 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. DFT calculations provided insight into the mechanistic aspects of the transformation and rationalized the observed isomeric preference towards the SF4Cl derivatives. Ultimately, this glovebox-free method selectively dispatches three classes of compounds upon reaction condition finetuning. Furthermore, first-in-class transformations are reported, including the preparation of aliphatic SF4Cl intermediates, their transformation into aliphatic sulfur pentafluoride analogs, and posttransformations that allow accessing highly complex SF4-bridged scaffolds.