Metal-Free S-Arylation of Phosphorothioate Diesters and Related Compounds with Diaryliodonium Salts

Synthesis of Dithioester Derivatives by Base-Mediated Fragmentation of 1,3-Dithiolanes

Dithioesters are important agents for chain transfer in polymer chemistry and precursors in the synthesis of heterocycles. Straightforward approaches to their synthesis are therefore in demand. Outlined herein is a method to access such compounds in one-pot. 2-Aryl-1,3-dithiolanes undergo ring fragmentation with LiHMDS in CPME to generate aryl-dithiocarboxylates in 5 min at 100 °C. These anions are subsequently captured in the second step by addition of various alkyl halides and diaryliodonium salts to furnish a large library of dithioesters in good yields. The method can be also employed in a one-pot, one-step manner for alkyl bromides and allows the synthesis of dithioesters in gram scale.

Iodoarene Activation: Take a Leap Forward toward Green and Sustainable Transformations

Constructing chemical bonds under green sustainable conditions has drawn attention from environmental and economic perspectives. The dissociation of (hetero)aryl-halide bonds is a crucial step of most arylations affording (hetero)arene derivatives. Herein, we summarize the (hetero)aryl halides activation enabling the direct (hetero)arylation of trapping reagents and construction of highly functionalized (hetero)arenes under benign conditions. The strategies for the activation of aryl iodides are classified into (a) hypervalent iodoarene activation followed by functionalization under thermal/photochemical conditions, (b) aryl-I bond dissociation in the presence of bases with/without organic catalysts and promoters, (c) photoinduced aryl-I bond dissociation in the presence/absence of organophotocatalysts, (d) electrochemical activation of aryl iodides by direct/indirect electrolysis mediated by organocatalysts and mediators acting as electron shuttles, and (e) electrophotochemical activation of aryl iodides mediated by redox-active organocatalysts. These activation modes result in aryl iodides exhibiting diverse reactivity as formal aryl cations/radicals/anions and aryne precursors. The coupling of these reactive intermediates with trapping reagents leads to the facile and selective formation of C-C and C-heteroatom bonds. These ecofriendly, inexpensive, and functional group-tolerant activation strategies offer green alternatives to transition metal-based catalysis.

Visible-Light-Induced Phosphorothioation of Alkenyl Sulfonium Salts with S8 and H-Phosphonates

An efficient and practical method for synthesizing vinyl phosphorothioates has been demonstrated through a visible-light-induced three-component reaction of alkenyl sulfonium salts, S8, and H-phosphonates. This method facilitates the synthesis of a diverse range of vinyl phosphorothioates with a wide substrate scope and functional group tolerance. Preliminary mechanistic studies suggest that the reaction involves a phosphorothioate radical-triggered process.

New Frontiers in phosphorothioate formation: harnessing inorganic phosphorus sources

Organic phosphorothioates are a class of organic compounds containing the C-S-P structural motif, known for their unique physical and chemical properties. These compounds hold significant value in various fields, including agriculture, pharmaceuticals, and materials science, particularly playing a crucial role in agrochemicals and nucleotide modification. Traditionally, phosphorothioates have been synthesized primarily through the formation of P-S bonds or direct phosphorothioation reactions from organic phosphorus sources such as P(O)H and P(O)SH. In recent years, new strategies utilizing inorganic phosphorus sources, such as P4S10 and white phosphorus (P4), have emerged as a dynamic area of research. This review highlights the latest advancements in the synthesis of phosphorothioates and phosphoropolythioates from inorganic phosphorus sources, focusing on their applicability, mechanisms, current limitations, and potential future directions.

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

Diaryliodonium salts have become widely recognized as arylating agents in the last two decades. Both, symmetrical and unsymmetrical forms of these salts serve as effective electrophilic arylating reagents in various organic syntheses. The use of diaryliodoniums in C-C and carbon-heteroatom bond formations, particularly under metal-free conditions, has further enhanced the popularity of these reagents. In this review, we concentrate on various arylation reactions involving carbon and other heteroatoms, encompassing rearrangement reactions in the absence of any metal catalyst, and summarize advancements made in the last five years.

Identification of O-arylated huperzinines as novel cholinergic anti-inflammatory pathway agonists against gout arthritis

Lycodine alkaloids are important natural products with diverse biological effects. In this manuscript, we set out the first structural optimization of the 2-pyridone moiety of Lycodine alkaloid via selective O-arylation under metal-free conditions and obtained a series of potent bioactive molecules against monosodium urate (MSU)-induced IL-1β production. Further investigations demonstrated that these natural product derivatives could activate the neuro-immunomodulatory cholinergic anti-inflammatory pathway (CAP) to block the initial phase of NLRP3 inflammasome activation. Compared with the clinical drugs hydrocortisone and indomethacin, as well as commercially available CAP agonists GTS-21 and pnu282987, 3k and 3q possessed greater potency against MSU-induced IL-1β production. Meanwhile, these molecules possessed less cytotoxicity against promonocytic THP-1 macrophages when compared with colchicine. This work reports a concise strategy for direct modification of 2-pyridone moiety from natural Lycodine alkaloids, and provides novel frameworks for discovering CAP activators and drugs for gout arthritis.

Visible Light/Copper Catalysis-Enabled Arylation and Alkenylation of Phosphorothioates via Site-Selective C-H Thianthrenation

An efficient visible light/copper-enabled arylation and alkenylation of phosphorothioates with thianthrenium salts via a C(sp2)-S cross-coupling reaction have been demonstrated. This strategy uses aryl/alkenyl thianthrenium salts as new electrophilic reagents, which can be easily prepared by the site-selective C-H thianthrenation of arenes/alkenes with high regioselectivity. Mechanistic studies revealed a crucial role of the in situ formed copper-sulfur complex, which undergoes a facile SET process with the thianthrenium salts under visible light conditions, thereby successfully achieving the desired cross-coupling reactivity.

Hydro-phosphorothiolation of Styrene and Cyclopropane with S-Hydrogen Phosphorothioates under Ambient Conditions

A metal-free hexafluoroisopropanol-mediated hydro-phosphorothiolation of styrenes and donor-acceptor cyclopropanes with S-hydrogen phosphorothioates in a Markovnikov fashion has been developed under ambient reaction conditions to afford a library of S-alkyl phosphorothioates. Notably, this strategy provides a simple and efficient way to produce biologically significant kitazin and iprobenfos derivatives. Mechanistic studies disclose that the reaction proceeds through a carbocation intermediate.

A highly efficient catalytic method for the synthesis of phosphite diesters

In contrast to conventional methods that rely on stoichiometric activation of phosphonylating reagents, we have developed a highly efficient catalytic method for the synthesis of phosphite diesters using a readily available phosphonylation reagent and alcohols with environmentally benign Zn(ii) catalysts. Two alcohols could be introduced consecutively on the P center with release of trifluoroethanol as the sole byproduct, without any additive, under mild conditions. The products could be oxidized smoothly to access phosphate triesters. A range of alcohols, including sterically demanding and highly functionalized alcohols such as carbohydrates and nucleosides, can be applied in this reaction.

TsCl promoted deoxygenative phosphorothiolation of quinoline N-oxides towards S-quinolyl phosphorothioates

A convenient, efficient and practical approach for the synthesis of S-quinolyl phosphorothioates via cheap TsCl promoted deoxygenative C2-H phosphorothiolation of quinoline N-oxides with readily available triethylammonium O,O-dialkylphosphorothioates was developed. The reaction performed well under transition-metal-free conditions at room temperature with a very short reaction time (10-20 min). Preliminary studies showed that the current transformation underwent a nucleophilic substitution process.

Synthesis of unsymmetric phosphorotrithioates by sequential coupling of 1,1-dichloro-N,N-diethylphosphanamine with thiols and sulfenyl chloride

Herein, we present the first, one-step, direct synthesis of unsymmetric phosphorotrithioates through a process involving sequential coupling of 1,1-dichloro-N,N-diethylphosphanamine with thiols and sulfenyl chloride. This method showcases excellent functional group tolerance, substrate compatibility, and mild reaction conditions, offering a streamlined approach for the challenging phosphorotrithioate synthesis. Additionally, the applicability of this method can be extended to the synthesis of mixed phosphoroselenodithioates.

Metal-free and atom-efficient protocol for diarylation of selenocyanate by diaryliodonium salts

We developed an atom- and reaction mass efficient strategy for the preparation of diarylselenides using iodonium salts as reactants. The developed approach allows the obtaining of diarylselenides from the corresponding trimethoxyphenyl-substituted iodonium salts via a two-step one-pot reaction sequence. The proposed metal-free methodology is based on the involvement of both iodonium aryl groups for diarylation.