Synthesis of deuteriodifluoromethylthiolated isocoumarins-1-imines and isocoumarins enabled by multi-component reagents system (MCRS).

The combining use of BnSCF2D, mCPBA and Tf2O serves as an efficient multi-component reagents system (MCRS) for the synthesis of deuteriodifluoromethylthiolated isocoumarins-1-imines/isocoumarins via intramolecular cyclization/deuteriodifluoromethylthiolation of 2-alkynylbenzamides/2-alkynylbenzoates. The approach features the generation of the crucial reactive electrophilic sulfonium salt through a sequence process involving the oxidation of BnSCF2D by mCPBA followed by Tf2O promoted activation.

Synthesis of 4-functionalized pyrazoles via oxidative thio- or selenocyanation mediated by PhICl2 and NH4SCN/KSeCN.

A series of 4-thio/seleno-cyanated pyrazoles was conveniently synthesized from 4-unsubstituted pyrazoles using NH4SCN/KSeCN as thio/selenocyanogen sources and PhICl2 as the hypervalent iodine oxidant. This metal-free approach was postulated to involve the in situ generation of reactive thio/selenocyanogen chloride (Cl-SCN/SeCN) from the reaction of PhICl2 and NH4SCN/KSeCN, followed by an electrophilic thio/selenocyanation of the pyrazole skeleton.

In Situ Growth of Iron Sulfide on Fast Charge Transfer V2 C-MXene for Superior Sodium Storage Anodes.

Due to the upstream pressure of lithium resources, low-cost sodium-ion batteries (SIBs) have become the most potential candidates for energy storage systems in the new era. However, anode materials of SIBs have always been a major problem in their development. To address this, V2 C/Fe7 S8 @C composites with hierarchical structures prepared via an in situ synthesis method are proposed here. The 2D V2 C-MXene as the growth substrate for Fe7 S8  greatly improves the rate capability of SIBs, and the carbon layer on the surface provides a guarantee for charge-discharge stability. Unexpectedly, the V2 C/Fe7 S8 @C anode achieves satisfactory sodium storage capacity and exceptional rate performance (389.7 mAh g-1  at 5 A g-1 ). The sodium storage mechanism and origin of composites are thoroughly studied via ex situ characterization techniques and first-principles calculations. Furthermore, the constructed sodium-ion capacitor assembled with N-doped porous carbon delivers excellent energy density (135 Wh kg-1 ) and power density (11 kW kg-1 ), showing certain practical value. This work provides an advanced system of sodium storage anode materials and broadens the possibility of MXene-based materials in the energy storage.

Divergent synthesis of 2-methylthioindole and 2-unsubstituted indole derivatives mediated by SOCl2 and dimethyl/diethyl sulfoxides.

A metal-free divergent synthesis of indole compounds dependent on a reagent via intramolecular C(sp2)-H amination was described. The reaction of 2-vinylanilines with DMSO/SOCl2 at 70 °C was found to give 2-thiomethylindoles, while replacing DMSO with diethyl sulfoxide afforded 2-unsubstituted indoles in a highly selective manner.

Unexpected Substituent Effects in Spiro-Compound Formation: Steering N-Aryl Propynamides and DMSO toward Site-Specific Sulfination in Quinolin-2-ones or Spiro[4,5]trienones.

A highly substituent-dependent rearrangement allows for the novel and SOCl2-induced divergent synthesis of 3-methylthioquinolin-2-ones and 3-methylthiospiro[4.5]trienones through intramolecular electrophilic cyclization of N-aryl propyamides. DMSO acts as both solvent and sulfur source, and use of DMSO-h6/d6 enables the incorporation of SCH3 or SCD3 moieties to the 3-position of the heterocyclic framework. Different para-substituents trigger divergent reaction pathways leading to the formation of quinolin-2-ones for mild substituents and spiro[4,5]trienones for both electron-withdrawing and -donating substituents, respectively. On the basis of both computational and experimental results, a new mechanism has been put forward that accounts for the exclusive spirolization/defluorination process and the surprising substituent effects.

Thianthrene/TfOH-catalyzed electrophilic halogenations using N-halosuccinimides as the halogen source.

Organohalides are vital organic building blocks with applications spanning various fields. However, direct halogenation of certain neutral or unreactive substrates by using solely the regular halogenating reagents has proven challenging. Although various halogenation approaches via activating halogenating reagents or substrates have emerged, a catalytic system enabling broad substrate applicability and diverse halogenation types remains relatively underexplored. Inspired by the halogenation of arenes via thianthrenation of arenes, here we report that thianthrene, in combined use with trifluoromethanesulfonic acid (TfOH), could work as an effective catalytic system to activate regular halogenating reagents (NXS). This new protocol could accomplish multiple types of halogenation of organic compounds including aromatics, olefins, alkynes and ketones. The mechanism study indicated that a highly reactive electrophilic halogen thianthrenium species, formed in situ from the reaction of NXS with thianthrene in the presence of TfOH, was crucial for the efficient halogenation process.

Design of dual carbon encapsulated porous micron silicon composite with compact surface for enhanced reaction kinetics of lithium-ion battery anodes.

Developing high-performance composites with fast charging and superior cycle life is paramount for lithium-ion batteries (LIBs). Herein, we synthesized a double-shell carbon-coated porous structure composite with a compact surface (P-Si@rGO@C) using low-cost commercial micron-sized silicon (Si) instead of nanoscale silicon. Results reveal that the unique P-Si@rGO@C features high adaptability to volume expansion, accelerates electron/ion transmission rate, and forms a stable solid electrolyte interphase (SEI) film. This phenomenon arises from the synergistic effect of abundant internal voids and an external double-layer carbon shell with a dense surface. Specifically, the P-Si@rGO@C anode exhibits a high initial coulombic efficiency (ICE) (88.0 %), impressive rate-capability (612.1 mAh/g at 2C), and exceptional long-term cyclability (972.2 mAh/g over 500 cycles at 0.5C). Further kinetic studies elucidate the diffusion-capacitance hybrid energy storage mechanism and reveal an improved Li+ diffusion coefficient (from 3.47 × 10-11 to 2.85 × 10-9 cm2 s-1). Ex-situ characterization confirms the crystal phase change of micron-sized Si and the formation of a stable LiF-rich SEI. Theoretical calculations support these findings by demonstrating an enhancement in the adsorption ability of Si to Li+ (from -0.89 to -0.97 eV) and a reduction in the energy migration barrier (from 0.35 to 0.18 eV). Additionally, practical LixSi powder is shown to increase the ICE of full cells from 67.4 % to 87.9 %. Furthermore, a pouch cell utilizing the prelithiated P-Si@rGO@C anode paired with LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode delivers a high initial reversible capacity of 7.2 mAh and 76.8 % capacity retention after 100 cycles. This work provides insights into the application of commercial silicon-aluminum alloy powder in the anode of high-energy LIBs.

Intramolecular Heterocyclization/Fluoromethylthiolation of Alkynes Enabled by a Multicomponent Reagent System.

The BnSRf (Rf = CF2H or CF3)/mCPBA/Tf2O system was found to be an effective multicomponent reagent system for the one-pot synthesis of di/trifluoromethylthiolated heterocycles from alkynes. The reaction was postulated to proceed via a cascade sequence involving the oxidation of BnSRf by mCPBA, activation of the in situ-generated sulfoxide by Tf2O, and intramolecular cyclization/fluoromethylthiolation of the alkyne substrates enabled by the formed electrophilic sulfonium salt to give di/trifluoromethylthiolated heterocycles.

Aryl iodine-catalysed divergent synthesis of isobenzofuranones and isocoumarins via oxidative 1,2-aryl migration/elimination.

The divergent synthesis of isobenzofuranones and isocoumarins was realized from the reaction of 2-alkenyl benzoic acids and mCPBA in the presence of catalytic aryl iodine and (±)-10-camphorsulfonic acid (CSA). The organocatalytic oxidative reaction is assumed to undergo a cascade process involving lactonization, 1,2-aryl migration and elimination enabled by a modified Koser reagent generated in situ.

Trifluoromethylthiolation/Selenolation and Lactonization of 2-Alkynylbenzoate: The Application of Benzyl Trifluoromethyl Sulfoxide/Selenium Sulfoxides as SCF3/SeCF3 Reagents.

The combined use of BnS(O)CF3/BnSe(O)CF3 with Tf2O as SCF3/SeCF3 reagents was implemented to realize an efficient synthesis of biologically interesting 4-(trifluoromethylthio/trifluoromethylseleno)isocoumarins from 2-alkynylbenzoates. The mechanistic pathway was postulated to involve formation of the electrophilic SCF3/SeCF3 species via interrupted Pummerer reactions followed by a concerted trifluoromethylthiolation/selenolation and lactonization process.

Synthesis of 3-SCF2H-/3-SCF3-chromones via Interrupted Pummerer Reaction/Intramolecular Cyclization Mediated by Difluoromethyl or Trifluoromethyl Sulfoxide and Tf2O.

The reaction of alkynyl aryl ketones bearing an o-methoxy group with difluoromethyl sulfoxide in the presence of Tf2O was found to conveniently afford the corresponding 3-SCF2H-substituted chromones. The combining use of difluoromethyl sulfoxide/Tf2O could represent the first reagents system that can introduce the biologically important SCF2H moiety under base-free conditions via an interrupted Pummerer reaction. The same protocol could also be applied to the synthesis of 3-SCF3-substituted chromones by replacing difluoromethyl sulfoxide with trifluoromethyl sulfoxide and CH3CN with toluene.

DMSO/SOCl2-mediated C(sp2)-H amination: switchable synthesis of 3-unsubstituted indole and 3-methylthioindole derivatives.

The reaction of 2-alkenylanilines with SOCl2 in DMSO was found to selectively afford 3-unsubstituted indoles and 3-methylthioindoles. This switchable approach was found to be temperature-dependent: at room temperature, the reaction afforded 3-unsubstituted indoles through intramolecular cyclization and elimination; while at higher temperature, the reaction gave 3-methylthioindoles via further electrophilic methylthiolation.