Aryl sulfonyl chlorides and sodium aryl sulfinates: non-volatile, non-stench, and non-toxic aryl thiol surrogates for direct aryl-sulfenylation of C–H bonds

Synthesis of disulfides and 3-sulfenylchromones from sodium sulfinates catalyzed by TBAI

A new synthetic method for disulfides and 3-sulfenylchromones is reported. This innovative approach is based on the tetrabutylammonium iodide (TBAI)/H2SO4 reduction system using sodium sulfinate as key component, thus eliminating the need for thiols and redox reagents commonly used in traditional methods. Various disulfides and 3-sulfenylchromones were obtained in moderate to excellent yields through this methodology. Mechanistic studies indicate that thiosulfonates play an important role in the reaction process.

Direct C-H Sulfuration: Synthesis of Disulfides, Dithiocarbamates, Xanthates, Thiocarbamates and Thiocarbonates

In light of the important biological activities and widespread applications of organic disulfides, dithiocarbamates, xanthates, thiocarbamates and thiocarbonates, the continual persuit of efficient methods for their synthesis remains crucial. Traditionally, the preparation of such compounds heavily relied on intricate multi-step syntheses and the use of highly prefunctionalized starting materials. Over the past two decades, the direct sulfuration of C-H bonds has evolved into a straightforward, atom- and step-economical method for the preparation of organosulfur compounds. This review aims to provide an up-to-date discussion on direct C-H disulfuration, dithiocarbamation, xanthylation, thiocarbamation and thiocarbonation, with a special focus on describing scopes and mechanistic aspects. Moreover, the synthetic limitations and applications of some of these methodologies, along with the key unsolved challenges to be addressed in the future are also discussed. The majority of examples covered in this review are accomplished via metal-free, photochemical or electrochemical approaches, which are in alignment with the overraching objectives of green and sustainable chemistry. This comprehensive review aims to consolidate recent advancements, providing valuable insights into the dynamic landscape of efficient and sustainable synthetic strategies for these crucial classes of organosulfur compounds.

Recent advances in selective mono-/dichalcogenation and exclusive dichalcogenation of C(sp2)-H and C(sp3)-H bonds

Organochalcogen compounds are prevalent in numerous natural products, pharmaceuticals, agrochemicals, polymers, biological molecules and synthetic intermediates. Direct chalcogenation of C-H bonds has evolved as a step- and atom-economical method for the synthesis of chalcogen-bearing compounds. Nevertheless, direct C-H chalcogenation severely lags behind C-C, C-N and C-O bond formations. Moreover, compared with the C-H monochalcogenation, reports of selective mono-/dichalcogenation and exclusive dichalcogenation of C-H bonds are relatively scarce. The past decade has witnessed significant advancements in selective mono-/dichalcogenation and exclusive dichalcogenation of various C(sp2)-H and C(sp3)-H bonds via transition-metal-catalyzed/mediated, photocatalytic, electrochemical or metal-free approaches. In light of the significance of both mono- and dichalcogen-containing compounds in various fields of chemical science and the critical issue of chemoselectivity in organic synthesis, the present review systematically summarizes the advances in these research fields, with a special focus on elucidating scopes and mechanistic aspects. Moreover, the synthetic limitations, applications of some of these processes, the current challenges and our own perspectives on these highly active research fields are also discussed. Based on the substrate types and C-H bonds being chalcogenated, the present review is organized into four sections: (1) transition-metal-catalyzed/mediated chelation-assisted selective C-H mono-/dichalcogenation or exclusive dichalcogenation of (hetero)arenes; (2) directing group-free selective C-H mono-/dichalcogenation or exclusive dichalcogenation of electron-rich (hetero)arenes; (3) C(sp3)-H dichalcogenation; (4) dichalcogenation of both C(sp2)-H and C(sp3)-H bonds. We believe the present review will serve as an invaluable resource for future innovations and drug discovery.

(Hetero)aryl-SVI Fluorides: Synthetic Development and Opportunities

(Hetero)arylsulfur compounds where the S atom is in the oxidation state VI represent a large percentage of the molecular functionalities present in organic chemistry. More specifically, (hetero)aryl-SVI fluorides have recently received enormous attention because of their potential as chemical biology probes, as a result of their reactivity in a simple, modular, and efficient manner. Whereas the synthesis and application of the level 1 fluorination at SVI atoms (sulfonyl and sulfonimidoyl fluorides) have been widely studied and reviewed, the synthetic strategies towards higher levels of fluorination (levels 2 to 5) are somewhat more limited. This Minireview evaluates and summarizes the progress in the synthesis of highly fluorinated aryl-SVI compounds at all levels, discussing synthetic strategies, reactivity, the advantages and disadvantages of the synthetic procedures, the proposed mechanisms, and the potential upcoming opportunities.

Sulfonyl Chlorides as Thiol Surrogates for Carbon-Sulfur Bond Formation: One-Pot Synthesis of Thioethers and Thioesters

A method to synthesize thioethers and thioesters directly from readily available sulfonyl chlorides is reported. We demonstrate that a transient intermediate formed during phosphine-mediated deoxygenation of sulfonyl chlorides can be trapped in situ by activated alcohols or carboxylic acids to effect carbon-sulfur bond formation. The method is operationally simple and tolerates a broad range of functional groups. Special attention has been focused on the late-stage diversification of densely functionalized natural products and pharmaceuticals.

Unconventional approaches for the introduction of sulfur-based functional groups

Organosulfur compounds have a pivotal role in the functionalities of many natural products, pharmaceuticals and organic materials. For these reasons, the search for new methodologies for the formation of carbon-sulfur bonds has been the object of intensive work for organic chemists. However, the proposed strategies suffer from various drawbacks, such as volatility, toxicity, and instability of the sulfur sources or the use of VOC solvents. In this review, we summarise the recent protocols which have the goal of obtaining sulfones, thioethers, thiazines, thiazepines and sulfonamides in an unconventional and/or sustainable way. The use of starting materials less invasive and toxic with respect to the traditional reagents, alternative solvents such as water, ionic liquids or deep eutectic solvents, the exploitation of ultrasound and electrochemistry, increasing the efficiency of the process, are reported. Moreover, representative reaction mechanisms are also discussed.

Recent advances in intermolecular 1,2-difunctionalization of alkenes involving trifluoromethylthiolation

Trifluoromethylthiolative difunctionalization of alkenes, a cheap and abundant feedstock, which installs a trifluoromethylthiol (SCF3) group and another unique functional group across the carbon-carbon double bonds, provides an ideal strategy for the preparation of β-functionalized alkyl trifluoromethyl sulfides and has become a hot topic recently. This review aims to summarize the major progress in this exciting research area, with particular emphasis on the mechanistic aspects of the reaction pathways.

A Unified Strategy for Arylsulfur(VI) Fluorides from Aryl Halides: Access to Ar-SOF3 Compounds

A convenient protocol to selectively access various arylsulfur(VI) fluorides from commercially available aryl halides in a divergent fashion is presented. Firstly, a novel sulfenylation reaction with the electrophilic N-(chlorothio)phthalimide (Cl-S-Phth) and arylzinc reagents afforded the corresponding Ar-S-Phth compounds. Subsequently, the S(II) atom was selectively oxidized to distinct fluorinated sulfur(VI) compounds under mild conditions. Slight modifications on the oxidation protocol permit the chemoselective installation of 1, 3, or 4 fluorine atoms at the S(VI) center, affording the corresponding Ar-SO2 F, Ar-SOF3 , and Ar-SF4 Cl. Of notice, this strategy enables the effective introduction of the rare and underexplored -SOF3 moiety into various (hetero)aryl groups. Reactivity studies demonstrate that such elusive Ar-SOF3 can be utilized as a linchpin for the synthesis of highly coveted aryl sulfonimidoyl fluorides (Ar-SO(NR)F).

Cross-dehydrogenative Coupling Reactions Between Formamidic C(sp2)-H and X-H (X = C, O, N) Bonds

In the last decade, the scientific community has witnessed explosive growth in research on the direct carbamoylation of C-H and X-H (X = N, O) bonds with formamides via cross-dehydrogenative coupling reactions. This novel approach is an effective means of preparing a variety of carboxamide, carbamate as well as urea derivatives, which are prevalent in medicinal chemistry and natural product synthesis. This review elaborates the most important advances and developments in the field, with an emphasis on the reaction patterns and mechanisms.

N-Fluorobenzenesulfonimide: a useful and versatile reagent for the direct fluorination and amination of (hetero)aromatic C–H bonds

This review updates recent advances and developments in the direct fluorination and amination of (hetero)aromatic C–H bonds utilizing N-fluorobenzenesulfonimide, classified according to the type of catalyst.

This review updates recent advances and developments in the direct fluorination and amination of (hetero)aromatic C–H bonds utilizing N-fluorobenzenesulfonimide, classified according to the type of catalyst.