Boron-Promoted Umpolung Reaction of Sulfonyl Chlorides for the Stereospecific Synthesis of Thioglycosides via Reductive Deoxygenation Coupling Reactions

Synthesis of aryl thioglycosides by metal-free arylation of glycosyl thiols with diaryliodonium salts under basic conditions

Herein, we demonstrate the application of unsymmetrical iodonium salts towards S-arylation of glycosyl thiols under metal-free conditions, affording a various stereoretentive thioarylglycosides in moderate to good yields. The application of an inorganic base Cs2CO3 enables the C-S bond formation under mild and experimentally simple conditions at room temperature. The proper choice of auxiliary of the unsymmetrical iodonium salt enables the access to diverse functionalized aryl moieties including biphenyl groups and its incorporation into thioarylglycosides.

Exploring the Chemistry and Applications of Thio-, Seleno-, and Tellurosugars

Given the crucial roles of carbohydrates in energy supply, biochemical processes, signaling events and the pathogenesis of several diseases, the development of carbohydrate analogues, called glycomimetics, is a key research area in Glycobiology, Pharmacology, and Medicinal Chemistry. Among the many structural transformations explored, the replacement of endo- and exocyclic oxygen atoms by carbon (carbasugars) or heteroatoms, such as nitrogen (aza- and iminosugars), phosphorous (phosphasugars), sulfur (thiosugars), selenium (selenosugars) or tellurium (tellurosugars) have garnered significant attention. These isosteric substitutions can modulate the carbohydrate bioavailability, stability, and bioactivity, while introducing new properties, such as redox activity, interactions with pathological lectins and enzymes, or cytotoxic effects. In this manuscript we have focused on three major families of glycomimetics: thio-, seleno-, and tellurosugars. We provide a comprehensive review of the most relevant synthetic pathways leading to substitutions primarily at the endocyclic and glycosidic positions. The scope includes metal-catalyzed reactions, organocatalysis, electro- and photochemical transformations, free-radical processes, and automated syntheses. Additionally, mechanistic insights, stereoselectivity, and biological properties are also discussed. The structural diversity and promising bioactivities of these glycomimetics underscore their significance in this research area.

Palladium-Catalyzed Stereospecific Glycosylation Enables Divergent Synthesis of N-O-Linked Glycosides

We present a versatile palladium-catalyzed glycosylation platform that enables facile access to structurally diverse N-O-linked glycosides with constantly excellent regio- and stereoselectivities. Importantly, this approach offers a broad substrate scope, low catalyst loadings, and outstanding chemoselectivity, allowing for the selective reaction of oximes/hydroximic acids over hydroxyl groups that would otherwise pose challenges in conventional glycosylation methods. The synthetic utility of this method is further exemplified through a range of synthetic transformations and late-stage modification of bioactive molecules. Overall, our method provides an efficient toolkit for the synthesis of N-O-linked glycosides, which will facilitate their subsequent biological evaluations.

Synthesis of C(3) SCF3-Substituted Pyrrolidinoindoline by PIII/PV Redox Catalysis Using CF3SO2Cl as Electrophilic CF3S Reagent

This work reports a method for the catalytic synthesis of C(3) SCF3-substituted pyrrolidinindoline using a small-ring organophosphorus-based catalyst and a hydrosilane reductant, with trifluoromethanesulfonyl chloride as the electrophilic SCF3 reagent. This method can drive the conversion of tryptamine to the C(3) SCF3-substituted pyrrolidine indoline. The readily available, inexpensive trifluoromethanesulfonyl chloride could be activated as an electrophilic SCF3 source by PIII/PV redox catalysis and could efficiently participate in the reaction of tryptamines, thus providing various substituted C(3) SCF3-substituted pyrrolidinoindoline in moderate to excellent yields. This presented strategy features a broad substrate scope, and the structure has value for in-depth research.

Chemoselective Reactions of Functionalized Sulfonyl Halides

Chemoselective transformations of functionalized sulfonyl fluorides and chlorides are surveyed comprehensively. It is shown that sulfonyl fluorides provide an excellent selectivity control in their reactions. Thus, numerous conditions are tolerated by the SO2 F group - from amide and ester formation to directed ortho-lithiation and transition-metal-catalyzed cross-couplings. Meanwhile, sulfur (VI) fluoride exchange (SuFEx) is also compatible with numerous functional groups, thus confirming its title of "another click reaction". On the contrary, with a few exceptions, most transformations of functionalized sulfonyl chlorides typically occur at the SO2 Cl moiety.

A Method for the Synthesis of Thioindoles through Copper-Catalyzed C-S Bond Coupling Reaction

We herein report the copper-catalyzed C-S bond coupling reaction of indoles with N-thiosuccinimides, resulting in moderate to excellent yields of mono- and bis-sulfenylated compounds such as arylthioindoles, alkylthioindoles, selenylated indoles, and cysteine-substituted indoles. Thioarylation and thioglycosylation at the C2 position of indole alkaloids in the Radix Isatidis were achieved via structural modification. The first total syntheses of isatindigotindolosides III and IV have been successfully carried out. The electrophilic sulfenyl bromides generated in situ can play an important role in the catalytic cycle.

Facile and stereospecific synthesis of diverse β-N-glycosyl sulfonamide scaffolds via palladium catalysis

Glycosylation is an important strategy to improve the druggability of lead compounds. Here, we present a palladium-catalysed stereospecific N-glycosylation of sulfonamides. This approach stands out with wide substrate scope, high functional group tolerance, and easy scalability, furnishing a broad spectrum of densely functionalized β-N-glycosyl sulfonamides with good efficiency and exceptional regio-/stereoselectivity. Diverse drug-like glycosulfonamido scaffolds have been constructed via a late-stage diversification strategy and various facile synthetic transformations of the products. Collectively, the established protocol provides a valuable tool for efficiently preparing glycosyl sulfonamides to facilitate drug discovery.

New syntheses of thiosaccharides utilizing substitution reactions

Novel synthetic methods published since 2005 affording carbohydrates containing sulfur atom(s) are reviewed. The review is divided to subchapters based on the position of sulfur atom(s) in the sugar molecule. Only those methods that take advantage of substitution are discussed.

A Robust Copper-Catalyzed Cross-Coupling of Glycosyl Thiosulfonate and Boronic Acids Enables the Construction of Thioglycosides

An efficient and stereoretentive copper-catalyzed cross-coupling of glycosyl thiosulfonate and boronic acid for the construction of thioglycosides is described. The good functional group compatibility of this method allows the preparation of many bioactive aryl/alkenyl thioglycosides, including the hSGLT1 inhibitor.

Organophosphorus-Catalyzed "Dual-Substrate Deoxygenation" Strategy for C-S Bond Formation from Sulfonyl Chlorides and Alcohols/Acids

A green method to construct C-S bonds using sulfonyl chlorides and alcohols/acids via a P^III/P^V═O catalytic system is reported. The organophosphorus-catalyzed umpolung reaction promotes us to propose the "dual-substrate deoxygenation" strategy. Herein, we adopt the "dual-substrate deoxygenation" strategy, which achieves the deoxygenation of sulfonyl chlorides and alcohols/acids to synthesize thioethers/thioesters driven by P^III/P^V═O redox cycling. The catalytic method represents an operationally simple approach using stable phosphine oxide as a precatalyst and shows broad functional group tolerance. The potential application of this protocol is demonstrated by the late-stage diversification of drug analogues.

Chemical synthesis of oligosaccharides and their application in new drug research

Oligosaccharides are the ubiquitous molecules of life. In order to translate human bioglycosylation into clinical applications, homogeneous samples of oligosaccharides and glycoconjugates can be obtained by chemical, enzymatic or other biological methods for systematic studies. However, the structural complexity and diversity of glycans and their conjugates present a major challenge for the synthesis of such molecules. This review summarizes the chemical synthesis methods of oligosaccharides, the application of oligosaccharides in the field of medicinal chemistry according to their related biological activities, and shows the great prospect of oligosaccharides in the field of pharmaceutical chemistry.

Nonbasic Synthesis of Thioethers via Nickel-Catalyzed Reductive Thiolation Utilizing NBS-Like N-Thioimides as Electrophilic Sulfur Donors

The nonbasic synthesis of unsymmetrical thioethers via nickel-catalyzed reductive thiolation between aryl(hetero) iodides and N-thioimides is illustrated. N-Bromosuccinimide (NBS)-like N-thioimides were found quite reactive toward thiolation with carbon electrophiles, and a series of structurally varied thioethers were successfully prepared under mild reaction conditions. The transformation was featured with the new application of the NBS-like reagents, good functional group tolerance, and late-stage modification of biologically active scaffolds, thus providing an expeditious and efficient platform to construct polyfunctional thioethers.

Copper-Catalyzed C2- or C3-Thioglycosylation of Indoles with N-(Thioglycosides)succinimides: An Effective Strategy for the Total Synthesis of Isatindigotindolosides

Isatindigotindolosides, indoles containing a 1-S-β-glucopyranosyl unit at position C2, show promising bioactivity. Here, we report a copper-catalyzed C2- or C3-thioglycosylation of indoles with N-(thioglycosides)succinimides to construct indole alkaloid glucosides. This reaction is widely tolerant of functional groups, as various indoles and thioglycosides are suitable. It also provides a reliable method for performing late-stage modifications of natural products, such as gramine and melatonin. Total syntheses of isatindigotindolosides I and II were successfully accomplished using the C2-thioglycosylation reaction as a key step.

Controllable synthesis of disulfides and thiosulfonates from sodium sulfinates mediated by hydroiodic acid using ethanol and H2O as solvents

A controllable and rapid synthesis of disulfides and thiosulfonates from sodium sulfinates mediated by hydroiodic acid is presented for the first time. In these reactions, ethanol and H2O were employed as solvents to generate different products.

“Thiol-free synthesized” and sustainable thiolating synthons for nickel-catalyzed reductive assembly of sulfides with high efficiency

Unsymmetrical sulfides are widely found in the pharmaceutical industry, organic synthesis, and materials science.