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The homolysis of chemical bonds represents one of the most fundamental reactivities of excited molecules. Historically, it has been exploited to generate radicals under ultraviolet (UV) light irradiation. However, unlike most contemporary radical-generating mechanisms, the direct excitation to homolyze chemical bonds and produce aliphatic carbon-centered radicals under visible light remains rare, especially in metallaphotoredox cross couplings. Herein, we present our design of the dihydropyrimidoquinolinone (DHPQ) reagents derived from ketones, which can undergo formal deacylation and homolytic C-C bond cleavage to release alkyl radicals without external photocatalysts. Spectroscopic and computational analysis reveal unique optical and structural features of DHPQs, rationalizing their faster kinetics in alkyl radical generation than a structurally similar but visible-light transparent radical precursor. Such a capability allows DHPQ to facilitate a wide range of Ni-metallaphotoredox cross couplings with aryl, alkynyl and acyl halides. Other catalytic and non-catalyzed alkylative transformations of DHPQs are also feasible with various radical acceptors. We believe this work would be of broad interest, aiding the synthetic planning with simplified operation and expanding the synthetic reach of photocatalyst-free approaches in cutting-edge research., (© 2024 Wiley-VCH GmbH.)

The condensation of amino acids into peptides plays a crucial role in protein synthesis and is thus essential for understanding the origins of life. However, the spontaneous formation of peptides from amino acids in bulk aqueous media is energetically unfavorable, posing a challenge for elucidating plausible abiotic mechanisms. In this study, we investigate the formation of amide bonds between amino acids within highly supersaturated aerosol droplets containing dicyandiamide (DCD), a cyanide derivative potentially present on primordial Earth. Metastable states, i.e. supersaturation, within individual micron-sized droplets are studied using both an optical trap and a linear quadrupole electrodynamic balance. When irradiated with intense visible light, amide bond formation is observed to occur and can be monitored using vibrational bands in Raman spectra. The reaction rate is found to be strongly influenced by droplet size and kinetic modelling suggests that it is driven by the photochemical product of a DCD self-reaction. Our results highlight the potential of atmospheric aerosol particles as reaction environments for peptide synthesis and have potential implications for the prebiotic chemistry of early Earth., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Articular cartilage defects are a global challenge, causing substantial disability. Repairing large defects is problematic, often exceeding cartilage's self-healing capacity and damaging bone structures. To tackle this problem, a scaffold-mediated therapeutic ion delivery system is developed. These scaffolds are constructed from poly(ε-caprolactone) and strontium (Sr)-doped bioactive nanoglasses (SrBGn), creating a unique hierarchical structure featuring macropores from 3D printing, micropores, and nanotopologies due to SrBGn integration. The SrBGn-embedded scaffolds (SrBGn-µCh) release Sr, silicon (Si), and calcium (Ca) ions, which improve chondrocyte activation, adhesion, proliferation, and maturation-related gene expression. This multiple ion delivery significantly affects metabolic activity and maturation of chondrocytes. Importantly, Sr ions may play a role in chondrocyte regulation through the Notch signaling pathway. Notably, the scaffold's structure and topological cues expedite the recruitment, adhesion, spreading, and proliferation of chondrocytes and bone marrow-derived mesenchymal stem cells. Si and Ca ions accelerate osteogenic differentiation and blood vessel formation, while Sr ions enhance the polarization of M2 macrophages. The findings show that SrBGn-µCh scaffolds accelerate osteochondral defect repair by delivering multiple ions and providing structural/topological cues, ultimately supporting host cell functions and defect healing. This scaffold holds great promise for osteochondral repair applications., (© 2024 The Authors. Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

Biomimetic stress-relaxing hydrogels with reversible crosslinks attract significant attention for stem cell tissue regeneration compared with elastic hydrogels. However, stress-relaxing hyaluronic acid (HA)-based hydrogels fabricated using conventional technologies lack stability, biocompatibility, and mechanical tunability. Here, it is aimed to address these challenges by incorporating calcium or phosphate components into the HA backbone, which allows reversible crosslinking of HA with alginate to form interpenetrating networks, offering stability and mechanical tunability for mimicking cartilage. Diverse stress-relaxing hydrogels (τ1/2; SR50, 60-2000 s) are successfully prepared at ≈3 kPa stiffness with self-healing and shear-thinning abilities, favoring hydrogel injection. In vitro cell experiments with RNA sequencing analysis demonstrate that hydrogels tune chondrogenesis in a biphasic manner (hyaline or calcified) depending on the stress-relaxation properties and phosphate components. In vivo studies confirm the potential for biphasic chondrogenesis. These results indicate that the proposed stress-relaxing HA-based hydrogel with biphasic chondrogenesis (hyaline or calcified) is a promising material for cartilage regeneration., (© 2024 The Authors. Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

Pathological dermal scars such as keloids present significant clinical challenges lacking effective treatment options. Given the distinctive feature of highly stiffened scar tissues, deciphering how matrix mechanics regulate pathological progression can inform new therapeutic strategies. Here, it is shown that pathological dermal scar keloid fibroblasts display unique metamorphoses to stiffened matrix. Compared to normal fibroblasts, keloid fibroblasts show high sensitivity to stiffness rather than biochemical stimulation, activating cytoskeletal-to-nuclear mechanosensing molecules. Notably, keloid fibroblasts on stiff matrices exhibit nuclear softening, concomitant with reduced lamin A/C expression, and disrupted anchoring of lamina-associated chromatin. This nuclear softening, combined with weak adhesion and high contractility, facilitates the invasive migration of keloid fibroblasts through confining matrices. Inhibiting lamin A/C-driven nuclear softening, via lamin A/C overexpression or actin disruption, mitigates such invasiveness of keloid fibroblasts. These findings highlight the significance of the nuclear mechanics of keloid fibroblasts in scar pathogenesis and propose lamin A/C as a potential therapeutic target for managing pathological scars., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Osteoarthritis is a degenerative disease characterized by abnormal neurovascularization at the osteochondral junctions, the regulatory mechanisms of which remain poorly understood. In the present study, a murine osteoarthritic model with augmented neurovascularization at the osteochondral junction is used to examine this under-evaluated facet of degenerative joint dysfunction. Increased extracellular RNA (exRNA) content is identified in neurovascularized osteoarthritic joints. It is found that the amount of exRNA is positively correlated with the extent of neurovascularization and the expression of vascular endothelial growth factor (VEGF). In vitro binding assay and molecular docking demonstrate that synthetic RNAs bind to VEGF via electrostatic interactions. The RNA-VEGF complex promotes the migration and function of endothelial progenitor cells and trigeminal ganglion cells. The use of VEGF and VEGFR2 inhibitors significantly inhibits the amplification of the RNA-VEGF complex. Disruption of the RNA-VEGF complex by RNase and polyethyleneimine reduces its in vitro activities, as well as prevents excessive neurovascularization and osteochondral deterioration in vivo. The results of the present study suggest that exRNAs may be potential targets for regulating nerve and blood vessel ingrowth under physiological and pathological joint conditions., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

A novel method for the formation of Csp 3 -P III bonds via the nickel-catalyzed cross-coupling of Umpolung carbonyls and phosphine chlorides is reported herein. This process leads to a series of alkylphosphines, which are characterized as sulfides or borane-phosphine complexes after undergoing further transformation with moderate to good yields. Invaluable free alkylphosphines can be easily obtained by desulfurization or deboration of the products. A possible mechanistic pathway is also discussed. This report represents the first example of using renewable carbonyls as latent organometallic reagent surrogates for cross-coupling with heteroatom electrophiles., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The synthesis of arylamines from renewable resources under mild reaction conditions is highly desired for the sustainability of the chemical industry, where the production of hazardous waste is a prime concern. However, to date, there are very few tools in chemists' toolboxes that are able to produce arylamines in a sustainable manner. Herein, a robust one-pot approach for constructing bio-based arylamines via a combined photooxidative dearomatization-rearomatization strategy is presented. The developed methodology enables the synthesis of structurally complex amines in moderate-to-good isolated yields using biomass-derived phenols, natural α-amino acids, and naphthols under remarkably mild reaction conditions. For the photooxygenation of phenols, a novel chrysazine-based catalyst system was introduced, demonstrating its efficiency for the synthesis of natural products - hallerone, rengyolone, and the pharmaceutically relevant prodrug DHED., (© 2022 Wiley-VCH GmbH.)

The simple and efficient conversion of carbonyl compounds into functionalized alkanes via deoxygenation is highly enabling in chemical synthesis. This Review covers the recent methodology development in carbonyl and carboxyl deoxygenative functionalizations, highlighting some representative and significant contributions in this field. These advances are categorized based on the reactivity patterns of some oxygenated feedstock compounds, including aldehydes, ketones and carboxylic acids. Four types of reactive intermediates arising from aldehydes and ketones during the deoxygenation, namely, bis-electrophiles, carbenoids, bis-nucleophiles and alkyl radical equivalents, are presented, while the carboxylic acids mainly behave as tris-electrophiles when deoxygenated. In each subcategory, selected examples are organized according to the type of bond formation and discussed from a generalized mechanistic perspective., (© 2021 Wiley-VCH GmbH.)

Conventional approaches for Pd-catalyzed ring-opening cross-couplings of gem-difluorocyclopropanes with nucleophiles predominantly deliver the β-fluoroalkene scaffolds (linear selectivity). Herein, we report a cooperative strategy that can completely switch the reaction selectivity to give the alkylated α-fluoroalkene skeletons (branched selectivity). The unique reactivity of hydrazones that enables analogous inner-sphere 3,3'-reductive elimination driven by denitrogenation, as well as the assistance of steric-embedded N-heterocyclic carbene ligand, are the key to switch the regioselectivity. A wide range of hydrazones derived from naturally abundant aryl and alkyl aldehydes are well applicable, and various gem-difluorocyclopropanes, including modified pharmaceutical and biological molecules, can be efficiently functionalized with high value alkylated α-fluorinated alkene motifs under mild conditions., (© 2021 Wiley-VCH GmbH.)

Phenols are common precursors and core structures of a variety of industrial chemicals ranging from pharmaceuticals to polymers. However, the synthesis of site-specifically substituted phenols is challenging, and thus the development of new methods for this purpose would be highly desirable. Reported here is a protocol for palladium-catalyzed ortho-selective alkylation reactions of phenols with primary alcohols by a dearomatization-rearomatization strategy, with water as the sole by-product. Various substituted phenols and primary alcohols were compatible with the standard reaction conditions. The detailed mechanism of this transformation was also investigated., (© 2020 Wiley-VCH GmbH.)

We have developed an unprecedented Pd-catalyzed formal hydroalkylation of alkynes with hydrazones, which are generated in situ from naturally abundant aldehydes, as both alkylation reagents and hydrogen donors. The hydroalkylation proceeds with high regio- and stereoselectivity to form (Z)-alkenes, which are more difficult to generate compared to (E)-alkenes. The reaction is compatible with a wide range of functional groups, including hydroxy, ester, ketone, nitrile, boronic ester, amine, and halide groups. Furthermore, late-stage modifications of natural products and pharmaceutical derivatives exemplify its unique chemoselectivity, regioselectivity, and synthetic applicability. Mechanistic studies indicate the possible involvement of Pd-hydride intermediates., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Controlling reaction selectivity is a permanent pursuit for chemists. Regioselective catalysis, which exploits and/or overcomes innate steric and electronic bias to deliver diverse regio-enriched products from the same starting materials, represents a powerful tool for divergent synthesis. Recently, the 1,2-Markovnikov hydroalkylation of 1,3-dienes with simple hydrazones was reported to generate branched allylic compounds when a nickel catalyst was used. As part of the effort, shown here is that a complete switch of Markovnikov to anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type "carbanions" and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Transition-metal-catalyzed cross-couplings between aromatic electrophiles and nucleophiles have revolutionized modern chemical syntheses. Nevertheless, transition-metal-free approaches are preferable, considering the various issues caused by metal catalysts. This Minireview summarizes the recent progress in the light-enabled transition-metal-free formation of carbon-carbon and carbon-heteroatom bonds in aromatics, which opens a new avenue in aromatic reactions. From the mechanistic perspective, it classifies different reaction types of aryl electrophiles in an excited state with various nucleophiles. We believe this will provide more rationales for metal-free aromatic substitutions and cross-couplings with light, and guide the development of novel transformations of aromatic compounds facilitated by light., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Mechanical robustness is a central concern for moving artificial superhydrophobic surfaces to application practices. It is believed that bulk hydrophilic materials cannot be use to construct micro/nanoarchitectures for superhydrophobicity since abrasion-induced exposure of hydrophilic surfaces leads to remarkable degradation of water repellency. To address this challenge, the robust mechanical durability of a superhydrophobic surface with metal (hydrophilic) textures, through scalable construction of a flexible coral-reef-like hierarchical architecture on various substrates including metals, glasses, and ceramics, is demonstrated. Discontinuous coral-reef-like Cu architecture is built by solid-state spraying commercial electrolytic Cu particles (15-65 µm) at supersonic particle velocities. Subsequent flame oxidation is applied to introduce a porous hard surface oxide layer. Owing to the unique combination of the flexible coral-reef-like architecture and self-similar manner of the fluorinated hard oxide surface layer, the coating surface retains its water repellency with an extremely low roll-off angle (<2°) after cyclic sand-paper abrasion, mechanical bending, sand-grit erosion, knife-scratching, and heavy loading of simulated acid rain droplets. Strong adhesion to glass, ceramics, and metals up to 34 MPa can be achieved without using adhesive. The results show that the present superhydrophobic coating can have wide outdoor applications for self-cleaning and corrosion protection of metal parts., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Arylamines are commercially and synthetically useful compounds with a wide variety of applications. Their preparation has been traditionally achieved using metal-catalyzed C-N coupling reactions with aryl halides. In this work, 17 different diarylamines are prepared from phenols by using ammonium formate as the aminating reagent. Phenolic compounds are more desirable feedstocks, owing to their availability from lignin, making them valuable biorenewable alternatives to aryl halides. Ammonium formate is found to be a convenient surrogate for ammonia and a useful aminating reagent for phenols. Diarylamine products are obtained in good to excellent yields while only water and CO 2 are generated as byproducts of the transformation., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Transition metal catalyzed C-H functionalizations have been developed as powerful methods for C-C bond formations. Directing groups, removable directing groups, traceless directing groups, and transient directing groups (TDGs) have been successfully used to improve the reaction efficiencies. For the development of greener and more sustainable methods, C-H functionalization using a TDG that also serves as a reagent in aqueous solvent was investigated. The palladium-catalyzed C-H functionalization of tryptamine derivatives using ketones in water successfully generated tetrahydro-β-carbolines with a quaternary carbon center at C1. Deuterium-labeling experiments are discussed to provide insight into the mechanism. The C2-position of pyridine was also successfully functionalized by this strategy., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Converting organoboron compounds into the corresponding radicals has broad synthetic applications in organic chemistry. To achieve these transformations, various strong oxidants such as Mn(OAc) 3 , AgNO 3 /K 2 S 2 O 8 , and Cu(OAc) 2 , in stoichiometric amounts are required, proceeding by a single-electron transfer mechanism. Established herein is a distinct strategy for generating both aryl and alkyl radicals from organotrifluoroborates through an S H 2 process. This strategy is enabled by using water as the solvent, visible light as the energy input, and diacetyl as the promoter in the absence of any metal catalyst or redox reagent, thereby eliminating metal waste. To demonstrate its synthetic utility, an efficient acetylation to prepare valuable aryl (alkyl) methyl ketones is described and applications to construct C-C, C-I, C-Br, and C-S bonds are also feasible. Experimental evidence suggests that triplet diacetyl serves as the key intermediate in this process., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two series of isostructural lanthanide coordination complexes, namely, LIFM-42(Ln) (Ln=Eu, Tb, Gd, in which LIFM stands for the Lehn Institute of Functional Materials) and LIFM-43(Ln) (Ln=Er, Yb), were synthesized through the self-assembly of an excited-state intramolecular proton transfer (ESIPT) ligand, 5-[2-(5-fluoro-2-hydroxyphenyl)-4,5-bis(4-fluorophenyl)-1H-imidazol-1-yl]isophthalic acid (H 2 hpi2cf), with different lanthanide ions. In the coordination structures linked by the ligands and oxo-bridged Ln III 2 clusters (for LIFM-42(Ln) series) or isolated Ln III ions (for LIFM-43(Ln) series), the ESIPT ligand can serve as both the host and antenna for protecting and sensitizing the photoluminescence (PL) of Ln III ions. Meanwhile, the -OH⋅⋅⋅N active sites on the ligands are vacant, which provides availability to systematically explore the PL behavior of Ln complexes with ESIPT interference. Based on the accepting levels of different lanthanide ions, energy transfer can occur from the T 1 (K*) or T 1 (E*) (K*=excited keto form, E*=excited enol form) excited states of the ligand. Furthermore, the sensitized lanthanide luminescence in both visible and near-infrared regions, as well as the remaining K* emission of the ligand, can be modulated by the ESIPT responsiveness to different solvents, anions, and temperature., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C-C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)-O bond cleavages form valuable nitrogen-containing derivatives., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The oxidative cleavage of 1,2-diols is a fundamental organic transformation. The stoichiometric oxidants that are still predominantly used for such oxidative cleavage, such as H 5 IO 6  , Pb(OAc) 4  , and KMnO 4  , generate stoichiometric hazardous waste. Herein, we describe a widely applicable and highly selective silver(I)-catalyzed oxidative cleavage of 1,2-diols that consumes atmospheric oxygen as the sole oxidant, thus serving as a potentially greener alternative to the classical transformations., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lithium (Li) metal is a promising anode material for high-energy density batteries. However, the unstable and static solid electrolyte interphase (SEI) can be destroyed by the dynamic Li plating/stripping behavior on the Li anode surface, leading to side reactions and Li dendrites growth. Herein, we design a smart Li polyacrylic acid (LiPAA) SEI layer high elasticity to address the dynamic Li plating/stripping processes by self-adapting interface regulation, which is demonstrated by in situ AFM. With the high binding ability and excellent stability of the LiPAA polymer, the smart SEI can significantly reduce the side reactions and improve battery safety markedly. Stable cycling of 700 h is achieved in the LiPAA-Li/LiPAA-Li symmetrical cell. The innovative strategy of self-adapting SEI design is broadly applicable, providing opportunities for use in Li metal anodes., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Li anodes have been rapidly developed in recent years owing to the rising demand for higher-energy-density batteries. However, the safety issues induced by dendrites hinder the practical applications of Li anodes. Here, Li metal anodes stabilized by regulating lithium plating/stripping in vertically aligned microchannels are reported. The current density distribution and morphology evolution of the Li deposits on porous Cu current collectors are systematically analyzed. Based on simulations in COMSOL Multiphysics, the tip effect leads to preferential deposition on the microchannel walls, thus taking full advantage of the lightening rod theory of classical electromagnetism for restraining growth of Li dendrites. The Li anode with a porous Cu current collector achieves an enhanced cycle stability and a higher average Coulombic efficiency of 98.5% within 200 cycles. In addition, the resultant LiFePO 4 /Li full battery demonstrates excellent rate capability and stable cycling performance, thus demonstrating promise as a current collector for high-energy-density, safe rechargeable Li batteries., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In many heterogeneous catalysts, the interaction of supported metal species with a matrix can alter the electronic and morphological properties of the metal and manipulate its catalytic properties. III-nitride semiconductors have a unique ability to stabilize ultra-small ruthenium (Ru) clusters (ca. 0.8 nm) at a high loading density up to 5 wt %. n-Type III-nitride nanowires decorated with Ru sub-nanoclusters offer controlled surface charge properties and exhibit superior UV- and visible-light photocatalytic activity for ammonia synthesis at ambient temperature. A metal/semiconductor interfacial Schottky junction with a 0.94 eV barrier height can greatly facilitate photogenerated electron transfer from III-nitrides to Ru, rendering Ru an electron sink that promotes N≡N bond cleavage, and thereby achieving low-temperature ammonia synthesis., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

One of the classical ways to synthesize amines involves the coupling of carbonyl compounds and imines, either through enolate chemistry or acyl-based carbanion equivalents. We herein report an alternative strategy that is based on the use of aldehydes as alkyl carbanion equivalents in a reductive coupling with aryl imines. A wide array of secondary amines can be synthesized in moderate to high yields. This reaction is mediated by hydrazine and catalyzed by ruthenium(II) complexes, and it tolerates various functional groups, such as esters, amides, and nitriles., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Conjugate addition of carbon nucleophiles to electron-deficient olefins is one of the most powerful methods for forming carbon-carbon bonds. Despite great achievements in controlling the selectivity, variation of the carbon nucleophiles remains largely underexplored, with this approach relying mostly on organometallic reagents. Herein, we report that naturally abundant carbonyls can act as latent carbon nucleophiles for conjugate additions through a ruthenium-catalyzed process, with water and nitrogen as innocuous byproducts. The key to our success is homogeneous ruthenium(II) catalysis, combined with phosphines as spectator ligands and hydrazine as the reducing agent. This chemistry allows the incorporation of highly functionalized alkyl fragments into a vast array of electron-deficient olefins under mild reaction conditions in a reaction complementary to the classical organometallic-reagent-based conjugate additions mediated or catalyzed by "soft" transition metals., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We describe herein a palladium-catalyzed tandem oxidative arylation/olefination reaction of aromatic tethered alkenes/alkynes for the synthesis of dihydrobenzofurans and 2 H-chromene derivatives. This reaction features a 1,2-difunctionalization of C-C π-bond with two C-H bonds using O 2 as terminal oxidant at room temperature. The products obtained are valuable synthons and important scaffolds in biological agents and natural products., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein, we report a simple, redox-neutral and pH-neutral photo-induced carboiodination reaction under very mild conditions. This protocol employs readily available and cheap aryl bromides and sodium iodide as the starting materials to synthesize valuable functionalized dihydrobenzofurans and indolines in good to excellent yields with broad functional-group compatibility. As examples to demonstrate the utility of this protocol, gram-scale reactions and further transformations of the products were accomplished towards the synthesis of bioactive drug candidates. Most significantly, to the best of our knowledge, this reaction represents the first example of a cascade atom-radical-transfer addition involving the cleavage of aromatic C-Br bond., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The first example of homogeneous copper-catalyzed aerobic oxidation of aldehydes is reported. This method utilizes atmospheric oxygen as the sole oxidant, proceeds under extremely mild aqueous conditions, and covers a wide range of various functionalized aldehydes. Chromatography is generally not necessary for product purification., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A catalyst-free multicomponent CDC reaction is rarely reported, especially for the intermolecular tandem CDC cyclization, which represents an important strategy for constructing cyclic compounds. Herein, a three-component tandem CDC cyclization by a Pummerer-type rearrangement to afford biologically relevant isoindolinones from aromatic acids, amides, and DMSO, is described. This intermolecular tandem reaction undergoes a C(sp(2) )-H/C(sp(3) )-H cross-dehydrogenative coupling, C-N bond formation, and intramolecular amidation. A notable feature of this novel protocol is avoiding a catalyst and additive (apart from oxidant)., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A direct transition-metal-free coupling between alkynes and α-bromo carbonyl compounds has been developed with ultraviolet (UV) light in aqueous media. This method represents a facile approach to synthetically useful β,γ-alkynyl esters and amides stereoselectively from two readily available starting materials. As an example of the synthetic application of the products, the alkynyl esters were readily converted into allenoates., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The transition-metal-catalyzed amination of aryl halides has been the most powerful method for the formation of aryl amines over the past decades. Phenols are regarded as ideal alternatives to aryl halides as coupling partners in cross-couplings. An efficient palladium-catalyzed formal cross-coupling of phenols with various amines and anilines has now been developed. A variety of substituted phenols were compatible with the standard reaction conditions. Secondary and tertiary aryl amines could thus be synthesized in moderate to excellent yields., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An efficient Fe(III)-catalyzed cross-dehydrogenative arylation (CDA) of 3-substituted oxindoles with activated arenes under an air atmosphere was developed to provide 3,3'-disubstituted oxindoles in good yields., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

2,2'-Diaryl acids are key building blocks for some of the most important and high-performance polymers such as polyesters and polyamides (imides), as well as structural motifs of MOFs (metal-organic frameworks) and biological compounds. In this study, a direct, regiospecific and practical dimerization of simple aromatic acids to generate 2,2'-diaryl acids has been discovered, which proceeds through two rhodium-catalyzed C-H activations in water. This reaction can be easily scaled up to gram level by using only 0.4-0.6 mol % of the rhodium catalyst. As a proof-of-concept, the natural product ellagic acid was synthesized in two steps by this method., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Based on the analogous kagomé [Co3 (imda)2 ] layers (imda=imidazole-4,5-dicarboxylate), a family of pillar-layered frameworks with the formula of [Co3 (imda)2 (L)3 ]⋅(L)n ⋅xH2 O (1: L=pyrazine, n=0, x=8; 2: L=4,4'-bipyridine, n=1, x=8; 3: L=1,4-di(pyridin-4-yl)benzene, n=1, x=13; 4: L=4,4'-di(pyridin-4-yl)-1,1'-biphenyl, n=1, x=14) have been successfully synthesized by a hydrothermal/solvothermal method. Single-crystal structural analysis shows a significant increase in the interlayer distances synchronized with the extension of the pillar ligands, namely, 7.092(3) (1), 10.921(6) (2), 14.780(5) (3), and 19.165(4) Å (4). Despite the wrinkled kagomé layers in complexes 2-4, comprehensive magnetic characterizations revealed weakening of interlayer magnetic interactions and an increase in the degree of frustration as the pillar ligand becomes longer from 1 to 4; this leads to characteristic magnetic ground states. For compound 4, which has the longest interlayer distance, the interlayer interaction is so weak that the magnetic properties observed within the range of temperature measured would correspond to the frustrated layer., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The rhodium-catalyzed amidation of substituted benzoic acids with isocyanates by directed CH functionalization followed by decarboxylation to afford the corresponding N-aryl benzamides is demonstrated, in which the carboxylate serves as a unique, removable directing group. Notably, less common meta-substituted N-aryl benzamides are generated readily from more accessible para- or ortho-substituted groups by employing this strategy., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The thermal catalytic activity of GaN in non-oxidative alkane dehydroaromatization has been discovered for the first time. The origin of the catalytic activity was studied experimentally and theoretically. Commercially available GaN powders with a wurtzite crystal structure showed superior stability and reactivity for converting light alkanes, including methane, propane, n-butane, n-hexane and cyclohexane into benzene at an elevated temperature with high selectivity. The catalyst is highly robust and can be used repeatedly without noticeable deactivation., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Controlling reaction selectivity is an eternal pursuit for chemists working in chemical synthesis. As part of this endeavor, our group has been exploring the possibility of constructing different natural product skeletons from the same simple starting materials by using different catalytic systems. In our previous work, an isoflavanone skeleton was obtained from the annulation of a salicylaldehyde and an alkyne when a gold catalyst was employed. In this paper, it is shown that a coumarin skeleton can be efficiently obtained through an annulation reaction with the same starting materials, that is, terminal alkynes and salicylaldehydes, by simply switching to a rhodium catalyst. A plausible reaction mechanism is proposed for this new annulation based on isotopic substitution experiments., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The aniline carbamate is introduced as a new removable directing group for C-H activation. Its versatility and ability as a directing group are demonstrated by its use in the ortho-arylation of a wide variety of aniline derivatives under palladium(II) catalysis, with symmetric diaryliodonium salts as aryl donors. The reaction differs from previously reported arylations in its selectivity and its mechanism, as elucidated by kinetic and isotopic experiments. The directing group can also be easily removed under a variety of conditions., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Over the last decade, substantial research has led to the introduction of an impressive number of efficient procedures which allow the selective construction of CC bonds by directly connecting two different CH bonds under oxidative conditions. Common to these methodologies is the generation of the reactive intermediates in situ by activation of both CH bonds. This strategy was introduced by the group of Li as cross-dehydrogenative coupling (CDC) and discloses waste-minimized synthetic alternatives to classic coupling procedures which rely on the use of prefunctionalized starting materials. This Review highlights the recent progress in the field of cross-dehydrogenative C sp 3C formations and provides a comprehensive overview on existing procedures and employed methodologies., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Iron-oxide nanocrystals (IONCs) have been widely researched, owing to their unique physical and chemical properties. Herein, a new strategy that involves an electrospinning technique with the addition of a surfactant is reported as an effective method for the fabrication of shaped IONCs. With the same precursor compositions, only iron-oxide nanoparticles were obtained by using a sol-gel method without electrospinning. However, when the electrospinning technique was introduced, IONCs with special geometrical shapes (e.g., octahedral) were obtained. Characterization data indicated that the IONCs were composed of magnetite (Fe3O4) and maghemite (γ-Fe2O3), the ratio of which could be tuned by changing the concentration of the surfactants in the precursor solutions. A mechanism for the formation of IONCs is also proposed. The effect of surfactant on the decomposition of the iron complex is the main motivation for the formation of IONCs. In the sol-gel method without electrospinning, this effect is completely inhibited by the disturbance of long molecular chains. However, in the electrospinning strategy, such disturbance can be completely or partially diminished by the electrical force field during the electrospinning process and by the spatial effect of the nanofibers, thus leading to the formation of IONCs. Finally, the magnetic properties of the obtained IONCs were investigated. This strategy is versatile and environmentally friendly and it will be applicable to the synthesis of many other functional inorganic materials., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new strategy for the construction of biaryls by a transition-metal-free process is presented. A sequence of a Grignard reaction, dehydration, and oxidative aromatization affords the desired products in a one-pot fashion., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [BMIm][BF(4)] has demonstrated high efficiency when applied as a solvent in the oxidative nitro-Mannich carbon--carbon bond formation. The copper-catalyzed cross-dehydrogenative coupling (CDC) between N-phenyltetrahydroisoquinoline and nitromethane in [BMIm][BF(4)] occurred with high yield under the described reaction conditions. Both the ionic liquid and copper catalyst were recycled nine times with almost no lost of activity. The electrochemical behavior of the tertiary amine substrate and beta-nitroamine product was investigated employing [BMIm][BF(4)] as electrolyte solvent. The potentiostatic electrolysis in ionic liquid afforded the desired product with a high yield. This result and the cyclic voltammetric investigation provide a better understanding of the reaction mechanism, which involves radical and iminium cation intermediates.

An effective multi-component reaction (MCR) protocol has been developed for the construction of propargyl amines from aldehydes, amines and terminal alkynes by using microwave-assisted continuous-flow organic synthesis (MACOS). The process is catalysed by thin films of either copper or gold that achieve temperatures in excess of 900 degrees C when irradiated with low levels of microwave power. The process works equally well for premixed solutions of the three starting materials, or as three separate streams, which improves the combinatorial efficiency of the method. The process tolerates a wide variety of functional groups and heterocycles, and conversion over these diverse substrates ranges from 70-90 %.