Defluorinative Alkylboration of Alkenes Enabled by Dual Photoredox and Copper Catalysis.

A regioselectivity reversed three-component defluorinative alkylboration of alkenes with trifluoromethyls and bis(pinacolato)diboron via dual photoredox/copper catalysis is reported. The mild conditions are compatible with a wide array of nonactivated trifluoromethyl aromatics bearing electron-donating or electron-neutral substituents, trifluoroacetamides, and various nonactivated terminal and internal alkenes, enabling straightforward access to synthetically valuable γ-gem-difluoroalkyl boronates with high efficiency. Furthermore, this protocol is applicable to alkene-tethered trifluoromethyl aromatics to furnish gem-difluoromethylene-containing cyclic compounds. Synthetic applications and preliminary mechanistic studies are also presented.

Catalyst-Free Intermolecular Sulfonyl/Fluoromethyl Heteroarylation of Vinyl Ethers via Visible-Light-Induced Charge Transfer.

We report a visible-light-induced three-component sulfonyl-heteroarylation of vinyl ethers with sulfinates and five-membered heteroaryl chlorides. This protocol proceeds via electron-donor-acceptor (EDA) complexes between sulfinates and heteroaryl chlorides, giving ß-sulfonyl alkyl five-membered heteroarenes with high efficiency and excellent regioselectivity under mild and catalyst-free conditions. Utilization of CF3 SO2 Na or CF2 HSO2 Na as coupling partners further achieves three-component fluoromethyl-arylation of vinyl ethers, furnishing a series of valuable CF3 /CF2 H-incorporated alkyl heterocycles under mild conditions.

Electromagnetic forces in nanoparticles made of multilayer hyperbolic metamaterials.

We theoretically study the electromagnetic forces (optical gradient force, optical torque and vacuum friction) acting on a spherical anisotropic nanoparticle, which can be characterized by multilayer hyperbolic metamaterials (mHMMs). We find three important results about these forces: (i) Firstly, we theoretically demonstrate that the optical gradient force produced on a mHMMs nanoparticle can be flexibly tuned, from pushing the particle to pulling it, just via changing incident angle of illuminating plane light wave. (ii) Secondly, we find the optical torque acting on the mHMMs nanoparticle (its filling factor is around 0.3) can be tuned between positive and negative via changing the incident angle of circularly polarized plane light. Therefore, the rotating mHMMs nanoparticle with designed filling factor can be accelerated or decelerated by the optical torque. (iii) Finally, due to the large fluctuations of dipole polarizability of mHMMs nanoparticle with appropriate filling factor, we propose a new method to obtain the large enhancement of vacuum friction torque by designing the filling factor of the rotating mHMMs nanoparticle.

Catalytic three-component dicarbofunctionalization reactions involving radical capture by nickel.

The catalytic dicarbofunctionalization of unsaturated π bonds represents a powerful platform for the rapid construction of complex motifs. Despite remarkable progress, novel and efficient methods for achieving such transformations under milder conditions with chemo-, regio-, and stereoselectivity still remain a significant challenge; thus, their development is highly desirable. Recently, the merging of nickel catalysis with radical chemistry offers a new and benign platform for the catalytic dicarbofunctionalization of unsaturated π bonds with unprecedented reactivity and selectivity. In this review, we summarize the recent advances in this area by underpinning the catalytic domino transformations involving radical capture by nickel to provide a clear overview of reaction designs and mechanistic scenarios.

Selective Fluoromethyl Couplings of Alkynes via Nickel Catalysis.

We describe here a Ni-catalyzed intermolecular carbo-fluoromethylation of alkynes with aliphatic halides and fluoromethyl halides (BrCF2 H and ICH2 F) in the presence of zinc, enabling the facile and selective access to a diverse range of biologically valuable CF2 H/CH2 F-incorporated alkenes with excellent regio- and stereoselectivity. Notably, merging intramolecular radical cyclization with fluoromethyl coupling enables the expedient constructions of CF2 H/CH2 F-incorporated lactones and lactams with high efficiency and selectivity. Mechanistic studies disclose that this catalytic protocol proceeds via a radical addition to an alkyne followed by selective coupling with the fluoromethyl unit.

Light-Induced Divergent Cyanation of Alkynes Enabled by Phosphorus Radicals.

A photochemically induced selective and divergent cyanation reaction of alkynes, enabled by phosphorus radicals, is described. With the use of simple triarylphosphine as a co-catalyst, three cyanation reactions, including di-hydrocyanation, anti-Markovnikov hydrocyanation, and domino hydrocyanation/reduction, can be divergently achieved, furnishing a wide array of alkyl dinitriles, alkenyl nitriles, and alkyl nitriles under mild conditions. Terminal and internal alkynes are applicable with high efficiency and excellent selectivity. Synthetic applications for biologically active agents and preliminary experimental and computational mechanistic studies are reported.

Silver-Enabled General Radical Difluoromethylation Reaction with TMSCF2 H.

A silver-mediated oxidative difluoromethylation of styrenes and vinyl trifluoroborates with TMSCF2 H is reported for the first time. This method enables direct and facile access to CF2 H-alkenes from abundant alkenes with excellent functional-group compatibility. Moreover, this Ag/TMSCF2 H protocol could further enable a series of radical difluoromethylation reactions of a wide array of substrates, offering a generic and complementary platform for the construction of diversified C-CF2 H bonds.

Divergent Aminocarbonylations of Alkynes Enabled by Photoredox/Nickel Dual Catalysis.

A metallaphotoredox-catalyzed strategy for the selective and divergent aminocarbonylation of alkynes with amines and 1 atm of CO is reported. This synergistic protocol not only enables the Markovnikov-selective hydroaminocarbonylation of alkynes to afford α,ß-unsaturated amides, but also facilitates a sequential four-component hydroaminocarbonylation/radical alkylation in the presence of tertiary and secondary alkyl boronate esters, which allows for straightforward conversion of alkynes into corresponding amides. Preliminary mechanistic studies disclose that a photoinduced oxidative insertion of aniline and CO into nickel followed by a migratory insertion of (carbamoyl)nickel species could be involved.

General Method for Enantioselective Three-Component Carboarylation of Alkenes Enabled by Visible-Light Dual Photoredox/Nickel Catalysis.

A visible-light-promoted photoredox/nickel protocol for the enantioselective three-component carboarylation of alkenes with tertiary and secondary alkyltrifluoroborates and aryl bromides is described. This redox-neutral protocol allows for facile and divergent access to a wide array of enantioenriched ß-alkyl-α-arylated carbonyls, phosphonates, and sulfones in high yields and excellent enantioselectivities from readily available starting materials. We also report a modular and enantioselective synthesis of flurbiprofen analogs and piragliatin lead compound to demonstrate synthetic utility. Experimental and computational mechanistic studies were performed to gain insights into the mechanism and origin of chemo- and enantioselectivity.

Enantioselective Three-Component Fluoroalkylarylation of Unactivated Olefins through Nickel-Catalyzed Cross-Electrophile Coupling.

A nickel-catalyzed, enantioselective, three-component fluoroalkylarylation of unactivated alkenes with aryl halides and perfluoroalkyl iodides has been described. This cross-electrophile coupling protocol utilizes a chiral nickel/BiOx system as well as a pendant chelating group to facilitate the challenging three-component, asymmetric difunctionalization of unactivated alkenes, providing direct access to valuable chiral ß-fluoroalkyl arylalkanes with high efficiency and excellent enantioselectivity. The mild conditions allow for a broad substrate scope as well as good functional group toleration.

Direct and Regioselective C-H Oxidative Difluoromethylation of Heteroarenes.

The difluoromethyl group (CF2H) is of great interest in the area of medicinal chemistry. However, the investigation of molecular scaffolds containing this group has been hampered by the limitation of synthetic methods for the introduction of CF2H into heteroarenes. Herein we disclose a new strategy for the direct introduction of a difluoromethyl group into heteroarenes via the copper-mediated C-H oxidative difluoromethylation of heteroarenes with TMSCF2H. This mild and regioselective method enables the convenient synthesis of a range of difluoromethylated heteroarenes in high yields. The usage of 9,10-phenanthrenequinone (PQ) as an oxidant is critical to the success of this new difluoromethylation reaction.

Divergent 1,2-carboallylation of terminal alkynes enabled by metallaphotoredox catalysis with switchable triplet energy transfer.

We report a metallaphotoredox strategy for stereodivergent three-component carboallylation of terminal alkynes with allylic carbonates and alkyl trifluoroborates. This redox-neutral dual catalytic protocol utilizes commercially available organic photocatalyst 4CzIPN and nickel catalysts to trigger a radical addition/alkenyl-allyl coupling sequence, enabling straightforward access to functionalized 1,4-dienes in a highly chemo-, regio-selective, and stereodivergent fashion. This reaction features a broad substrate generality and a tunable triplet energy transfer control with pyrene as a simple triplet energy modulator, offering a facile synthesis of complex trans- and cis-selective skipped dienes with the same set of readily available substrates.

Ligand-controlled stereodivergent alkenylation of alkynes to access functionalized trans- and cis-1,3-dienes.

Precise stereocontrol of functionalized alkenes represents a long-standing research topic in organic synthesis. Nevertheless, the development of a catalytic, easily tunable synthetic approach for the stereodivergent synthesis of both E-selective and even more challenging Z-selective highly substituted 1,3-dienes from common substrates remains underexploited. Here, we report a photoredox and nickel dual catalytic strategy for the stereodivergent sulfonylalkenylation of terminal alkynes with vinyl triflates and sodium sulfinates under mild conditions. With a judicious choice of simple nickel catalyst and ligand, this method enables efficient and divergent access to both Z- and E-sulfonyl-1,3-dienes from the same set of simple starting materials. This method features broad substrate scope, good functional compatibility, and excellent chemo-, regio-, and stereoselectivity. Experimental and DFT mechanistic studies offer insights into the observed divergent stereoselectivity controlled by ligands.

High-Rate Lithium-Selenium Batteries Boosted by a Multifunctional Janus Separator Over a Wide Temperature Range of -30 °C to 60 °C.

Lithium-selenium batteries are characterized by high volumetric capacity comparable to Li-S batteries, while ≈1025 times higher electrical conductivity of Se than S is favorable for high-rate capability. However, they also suffer from the "shuttling effect" of lithium polyselenides (LPSes) and Li dendrite growth. Herein, a multifunctional Janus separator is designed by coating hierarchical nitrogen-doped carbon nanocages (hNCNC) and AlN nanowires on two sides of commercial polypropylene (PP) separator to overcome these hindrances. At room temperature, the Li-Se batteries with the Janus separator exhibit an unprecedented high-rate capability (331 mAh g-1 at 25 C) and retain a high capacity of 408 mAh g-1 at 3 C after 500 cycles. Moreover, the high retained capacities are achieved over a wide temperature range from -30 °C to 60 °C, showing the potential application under extreme environments. The excellent performances result from the "1+1>2" synergism of suppressed LPSes shuttling by chemisorption and electrocatalysis of hNCNC on the cathode side and suppressed Li-dendrite growth by thermally conductive AlN-network on the anode side, which can be well understood by the "Bucket Effect". This Janus separator provides a general strategy to develop high-performance lithium-chalcogen (Se, S, SeS2 ) batteries.

Anion Exchange Affinity-Based Controllable Surface Imprinting Synthesis of Ultrathin Imprinted Films for Protein Recognition.

Anion exchange affinity-based controllable surface imprinting is an effective approach to overcome low imprinting efficiency and high non-specific binding capacity. The template proteins were first immobilized on the anchored tetraalkylammonium groups of the nanoparticles via anion exchange affinity-based interactions, enabling monolayer sorption using a low template concentration. The combined use of surface-initiated photoiniferter-mediated polymerization to precisely control the imprinted film thickness, allowing the formation of homogeneous binding cavities, and the construction of effective binding sites resulted in a low non-specific binding capacity and high imprinting efficiency. The obtained imprinted films benefited from the anion exchange mechanism, exhibiting a higher imprinting factor and faster binding rate than the reference material. Binding tests revealed that the binding strength and selective recognition properties could be tuned to a certain extent by adjusting the NaCl concentration. Additionally, in contrast to the harsh template elution conditions of the covalent immobilization approach, over 80% of the template molecules were readily removed from the imprinted films using supersonic elution with an aqueous mixture of NaCl and HAc. Introducing template immobilization by anion exchange interactions to the synthesis of imprinted materials may provide a new approach for effective biomacromolecular imprinting.

Reductive hydrobenzylation of terminal alkynes via photoredox and nickel dual catalysis.

A photoredox/nickel dual catalyzed reductive hydrobenzylation of alkynes and benzyl chlorides by employing alkyl amines as a stoichiometric reductant is described. This synergistic protocol proceeds via Markovnikov-selective migratory insertion of an alkyne into nickel hydride, followed by cross-coupling with benzyl chloride, providing facile access to important 1,1-disubstituted olefins. This reaction enables the generation of nickel hydride by utilizing readily available alkyl amines as the hydrogen source. The mild conditions are compatible with a wide range of aryl and alkyl alkynes as well as chlorides.

Organic-photoredox-catalyzed three-component sulfonylative pyridylation of styrenes.

An efficient, metal-free protocol for the three-component sulfonylative pyridylation of styrenes via organic-photoredox catalysis is described. This metal-free process enables the direct and selective installation of sulfonyl and heteroaryl motifs and tolerates a wide array of functional groups as well as complex molecular scaffolds, that could complement previous methods and would be of interest in pharmaceutical research.

Identifying critical outbreak time window of controversial events based on sentiment analysis.

The response of netizens toward controversial events plays an important guiding role in the development of events. Based on the identification of such responses, this study aimed to determine the critical outbreak time window of events. The microblog texts related to an event were divided into seven emotional categories via multi-emotional analysis to capture the subtle emotions of netizens toward an event, i.e., public opinion. By detecting the characteristics of the text and regional coverage of emotions, an emotional coverage index that reflects the intensity of emotional impact was proposed to determine the mainstream emotion of netizens. By capturing the mutation characteristics of the impact intensity of mainstream emotions, the critical time window of the public opinion toward the event was obtained. The experimental results demonstrated that the proposed method can effectively identify the critical outbreak time window of controversial events, which can help authorities in preventing the further aggravation of events.

Sequential C-O decarboxylative vinylation/C-H arylation of cyclic oxalates via a nickel-catalyzed multicomponent radical cascade.

A selective, sequential C-O decarboxylative vinylation/C-H arylation of cyclic alcohol derivatives enabled by visible-light photoredox/nickel dual catalysis is described. This protocol utilizes a multicomponent radical cascade process, i.e. decarboxylative vinylation/1,5-HAT/aryl cross-coupling, to achieve efficient, site-selective dual-functionalization of saturated cyclic hydrocarbons in one single operation. This synergistic protocol provides straightforward access to sp3-enriched scaffolds and an alternative retrosynthetic disconnection to diversely functionalized saturated ring systems from the simple starting materials.

Photoredox-catalyzed branch-selective pyridylation of alkenes for the expedient synthesis of Triprolidine.

Alkenylpyridines are important pharmaceutical cores as well as versatile building blocks in organic synthesis. Heck reaction represents one of the most powerful platform for the construction of aryl-substituted alkenes, nevertheless, examples for Heck type coupling of alkenes with pyridines, particularly with branched selectivity, remain elusive. Here we report a catalytic, branch-selective pyridylation of alkenes via a sulfinate assisted photoredox catalysis. This reaction proceeds through a sequential radical addition/coupling/elimination, by utilizing readily available sodium sulfinates as reusable radical precursors as well as traceless elimination groups. This versatile protocol allows for the installation of important vinylpyridines with complete branched selectivity under mild conditions. Furthermore, this catalytic manifold is successfully applied to the expedient synthesis of Triprolidine.