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Single-atom site (SAS) catalysts have attracted considerable attention due to their excellent performance. However, most of the current research models of SAS catalysts are based on inorganic catalysts, where “metal and coordination atom interaction” cannot simulate the fine-tuning effect of organic ligands on metal catalytic centers in homogeneous catalysts. Therefore, certain chemical transformations in homogeneous catalysis cannot be perfectly replicated. Here, we used porous organic ligand polymers as the carrier, which effectively changes the charge regulation of nanoparticles and monoatomic metal catalysts. Drawing lessons from traditional homogeneous metal/ligand catalysis, we introduced various functional groups into the ligand polymers to adjust the electronic properties, and successfully realized the hydrosilylation of internal alkynes with high catalytic performance. The selectivity and catalytic efficiency under the Pd@POL-1 catalyst system were improved compared with previous studies. The internal alkynes with various structures can complete this reaction, and the ratio of E/Z can reach up to 100:1.

A series of 1,3-diphenylurea quinoxaline derivatives were synthesized and characterized by 1H, 13C NMR, and HR-ESI-MS analyses. In vitro cytotoxicity of the synthesized compounds was evaluated by MTT assay against MGC-803, H460, T-24, HeLa, HepG2, and SMMC-7721 human cancer cell lines. The results showed that most of the compounds exhibited effective cytotoxicity to the tested cancer cell lines. The mechanism of action of the two best active quinoxaline derivatives, compounds 2d and 2g was also investigated. They may be potent anticancer agents.

This study proposes two different methods of photocatalytic-controlled and visible light-induced selective oxidation of pyridiniums with air as the terminal oxidant. The key to these transformations is to choose the appropriate light source and photocatalyst. Pyridiniums are successfully converted into pyrroles through oxygen-mediated cycloaddition, proton-coupled electron transfer (PCET), pyridine ring opening, and recyclization. The other route is that pyridiniums selectively form 4-carbonyl pyridines through free radical rearrangement/aerobic oxidation under the catalysis of cobalt (II).

The study reported an electrochemically mediated method for the preparation of 2,1-benzoxazoles from o-nitrophenylacetylenes. Different from the traditional electrochemical reduction of nitro to ni...

Organic reactions using metal–organic frameworks (MOFs) as catalysts are promising with regard to their environmentally friendly features and potential catalyst recyclability. A robust Co(II)-MOF {[Co2(L-mac)(4,4-bpt)(H2O)]·3.5H2O}n (1) and its enantiomer {[Co2(D-mac)(4,4-bpt)(H2O)]·3.5H2O}n (2) (L/D-mac = basic forms of L/D-malic acid, 4,4-Hbpt = 3,5-di(pyridin-4-yl)-4H-1,2,4-triazole) have been gram-scale prepared under solvothermal conditions. Structural analysis reveals that mac manages Co(II) ions to form 1-D chains, which are further extended via 4,4-bpt connectors into a noninterpenetrating 3D framework architecture. It was found that 1 can be as a heterogeneous catalyst for multiple organic reactions, such as azide-alkyne cycloaddition and Friedel–Crafts reactions with good isolated yields and good recycle runs (at least five times without substantial degradation). Additionally, 1 can promote hydrosilylation of alkynes under harsh conditions with moderate yield.

An electrocatalyzed three-component cascade reaction of CO2, amines, and N-alkenylsulfonamides is developed, providing an environmentally friendly and efficient method of synthesizing a series of new carbamate compounds. This reaction meets the needs of green chemistry and promotes the participation of carbon dioxide in the three-component reaction by electro-oxidation. Pharmacological activity studies further prove that carbamate compounds have better activity than diamination by-products.

The novel method for the synthesis of gem-bisarylthio enamines and α-phenylthio ketones was developed via the coupling of α-substituted vinyl azides with thiols in the presence of tetrabutylammonium iodide (TBAI) as a redox catalyst and electrolyte at room temperature. Electronic properties were crucial in the generated products. This protocol features metal- and oxidant-free materials, broad tolerance of substrates, and mild reaction conditions.

Summary Single-atom-site (SAS) catalyst, as a highly reactive heterogeneous catalytic system, is one of the effective tools for complex organic synthesis. However, excessive attention on the catalysis and regulation of metal atoms has led to the neglect of the role of supports and ligands. Here, we employed a P-doped porous organic polymer as a support, as well as a ligand in the developed Pd SAS catalysts. The enrichment of the substrates by the pores, ligand action of the support, and high chemoselectivity and anti-agglomeration of SAS catalysts were the most striking features of this SAS catalyst. A highly selective distannylation of terminal alkynes with a new mechanism was achieved by using the multiple properties of SAS catalyst. This catalytic system offers an effective strategy to utilize the enrichment of the substrate by the pores to regulate the reaction mechanism, which opens a new frontier to use pores, ligands, and SASs for synergistic controlling reaction paths.

A metal-free and efficient visible-light-induced spirocyclization of indolyl-ynones with diselenides at room temperature under air atmosphere to prepare 3-selenospiroindolenines in moderate to good yields has been developed. The resulting products were tested for in vitro anticancer activity by MTT assay, and compounds 3 c and 3 e showed potent cancer cell-growth inhibition activities.

Methanol plays a crucial role in organic synthesis as a green C1 source. Herein, the concise α-methoxymethylation and aminomethylation of propiophenones are achieved via electrochemical reactions with methanol as both the solvent and reactant. Methanol plays dual roles in this reaction: it is oxidized to formaldehyde (HCHO) and functions as a nucleophile. This protocol was performed under oxidant- and transition metal-free conditions.

Owing to the inert nature of the pyridine ring and high activity of iminyl radicals, the reaction between pyridine and iminyl radicals remains a significant challenge. In this paper, we report the synthesis of sulfide imidazo[1,2-a]pyridines from vinyl azides, thiophenols, and pyridines via a radical [3 + 2] cycloaddition. Promoting inert pyridine and highly active iminyl radicals to participate in this intermolecular cycloaddition process is the striking feature of this protocol. The excellent antitumor activity of the prepared sulfide imidazopyridine scaffold demonstrated the synthetic utility of the developed synthetic protocol.

We developed an electrochemically enabled dehydrogenative annulation reaction of amides and alkynes for the synthesis of antitumor polycyclic isoquinolinones through a double C-H activation route. No external oxidant is required in this reaction, and electricity is used for Ru catalyst circulation. The most remarkable feature of this reaction is the effective improvement of product regioselectivity under mild electrolytic conditions in comparison with previously set strong oxidant conditions.

A visible-light mediated multicomponent cascade reaction of diselenides, alkynes, and sulfur dioxide was developed, in which multiple C-Se and C-S bonds were constructed, and unexpected β-sulfonylvinylselane compounds were generated with high selectivity for E configuration. β-Sulfonylvinylselane transformation into 1,4-oxathiine-4,4-dioxide and sulfonylethyne derivates was then investigated. A plausible mechanism involving a selenium radical-initiated cascade reaction and sulfur dioxide insertion was proposed.

Background Huangkui capsule (HKC), an anti-inflammatory Chinese modern patent medicine, has been now widely applied to the clinical therapy of diabetic nephropathy (DN). However, the overall therapeutic mechanisms in vivo are still unclear. Renal tubular epithelial-to-mesenchymal transition (EMT) is one of the major pathogenesis of renal interstitial fibrosis in DN. Recently, the physiological roles of NLRP3 inflammasome activation and toll-like receptor 4 (TLR4)/nuclear factor (NF)-κB signaling are closely linked to EMT. But, it remains elusive whether HKC regulates renal tubular EMT in vivo through targeting NLRP3 inflammasome activation and TLR4/NF-κB signaling in the kidneys. Purpose This study thereby aimed to clarify the therapeutic effects of HKC on renal tubular EMT in DN and its underlying mechanisms in vivo, compared to rapamycin (RAP). Methods Thirty-two rats were randomly divided into 4 groups: the Sham group, the Vehicle group, the HKC group and the RAP group. The early DN rat models were induced by unilateral nephrectomy combined with intraperitoneal injection of streptozotocin, and administered with HKC suspension or RAP suspension or vehicle after modeling for 4 weeks. Changes in the incipient renal lesions-related parameters in urine and blood were analyzed, respectively. Renal interstitial tissues were isolated for histomorphometry, immunohistochemistry and Western blotting at sacrifice. Results For the early DN rat models, HKC at the suitable dose of 2 g/kg/day ameliorated the general condition and biochemical parameters partially including kidney weight (KW), urinary albumin (UAlb), serum creatinine (Scr) and serum albumin (Alb), attenuated renal tubular EMT significantly and inhibited the activation of NLRP3 inflammasome in the kidneys obviously, which was superior to RAP generally. In addition to these, HKC also suppressed TLR4/NF-κB signaling in the kidneys of the DN model rats accurately, which was different from RAP specifically. Conclusion The results of this study further indicated that HKC, different from RAP, can alleviate renal tubular EMT in the DN model rats, likely by inhibiting NLRP3 inflammasome activation and TLR4/NF-κB signaling in the kidneys. Our findings thus provide the more accurate information in vivo about a clinical value of HKC, a traditional anti-inflammatory phytomedicine, in the treatment of the early DN patients.

Selective C1–H/C4–H carbonylation of N-methylene iminium salts, catalyzed by visible-light photoredox and oxygen in the air, has been reported. A ruthenium complex acts as a chemical switch to conduct two different reaction pathways and to afford two different kinds of products. In the absence of the ruthenium complex, the Csp2–H bonds adjacent to the nitrogen atoms are oxidized to α-lactams by the N-methyleneiminium substrates themselves as photosensitizers. In the presence of the ruthenium complex, the oxidation reaction site of quinoliniums is switched to the C4 region, resulting in the formation of 4-quinolones. The use of two transformations directly introduces oxygen into the nitrogen heterocyclic skeletons under an air atmosphere.

Background Recently, progression of chronic renal failure (CRF) has been closely associated with gut microbiota dysbiosis and intestinal metabolite-derived microinflammation. In China, total flavones of Abelmoschus manihot (TFA), a component of Abelmoschus manihot, has been widely used to delay CRF progression in clinics for the past two decades. However, the overall therapeutic mechanisms remain obscure. In this study, we designed experiments to investigate the renoprotective effects of TFA in CRF progression and its underlying mechanisms involved in gut microbiota and microinflammation, compared with febuxostat (FEB), a potent non-purine selective inhibitor of xanthine oxidase. Methods In vivo, the CRF rat models were induced by uninephrectomy, potassium oxonate, and proinflammatory diet, and received either TFA suspension, FEB, or vehicle after modeling for 28 days. In vitro, the RAW 264.7 cells were exposed to lipopolysaccharide (LPS) with or without TFA or FEB. Changes in parameters related to renal injury, gut microbiota dysbiosis, gut-derived metabolites, and microinflammation were analyzed in vivo. Changes in macrophage polarization and autophagy and its related signaling were analyzed both in vivo and in vitro. Results For the modified CRF model rats, the administration of TFA and FEB improved renal injury, including renal dysfunction and renal tubulointerstitial lesions; remodeled gut microbiota dysbiosis, including decreased Bacteroidales and Lactobacillales and increased Erysipelotrichales; regulated gut-derived metabolites, including d-amino acid oxidase, serine racemase, d-serine, and l-serine; inhibited microinflammation, including interleukin 1β (IL1β), tumor necrosis factor-α, and nuclear factor-κB; and modulated macrophage polarization, including markers of M1/M2 macrophages. More importantly, TFA and FEB reversed the expression of beclin1 (BECN1) and phosphorylation of p62 protein and light chain 3 (LC3) conversion in the kidneys by activating the adenosine monophosphate-activated protein kinase-sirtuin 1 (AMPK-SIRT1) signaling. Further, TFA and FEB have similar effects on macrophage polarization and autophagy and its related signaling in vitro. Conclusion In this study, we demonstrated that TFA, similar to FEB, exerts its renoprotective effects partially by therapeutically remodeling gut microbiota dysbiosis and inhibiting intestinal metabolite-derived microinflammation. This is achieved by adjusting autophagy-mediated macrophage polarization through AMPK-SIRT1 signaling. These findings provide more accurate information on the role of TFA in delaying CRF progression.

In general, halogenide anions are anodically oxidized into active species, which can be elemental halogen, halogen cations, or halogen radicals. These species subsequently react with substrates, such as olefins, ketones, or amines, to generate halogenated products. We review the mechanisms of these reactions.

A convenient and efficient palladium-catalyzed approach has been developed for the synthesis of 5-amino-1,2,4-oxadiazoles from amidoximes and isocyanides. Various 5-amino-1,2,4-oxadiazoles were obtained in moderate to high yields under mild conditions. The key to the success of this strategy involves new C-N bond and C-O bond formation via palladium-catalyzed isocyanide insertion.

An environmentally benign electrochemically enabled site-selective functionalization of indole or aniline derivatives with hexafluoroisopropanol in the presence of tetrabutyl ammonium hexafluorophosphate as the redox catalyst and electrolyte was demonstrated in this work. Under mild electro-oxidation conditions, a series of hexafluoroisopropoxy indole and aniline derivatives with pharmacological activity were obtained. This conversion does not need transition metals and oxidants, and has good functional group tolerance. The in vitro cytotoxicity of all compounds was evaluated by the MTT assay against four human cancer cell lines. The results revealed that hexafluoroisopropoxy indoles have good antitumor activity and compound 2i increased the intracellular levels of ROS and inhibited apoptosis in HeLa cells.

Environmentally benign electrochemically enabled chemoselective sulfonylation and hydrazination of C2,C3-unsubstituted indoles with arylsulfonyl hydrazide in the presence of ammonium bromide as a redox catalyst and electrolyte have been demonstrated in this work. Under mild electro-oxidation conditions, a series of indole hydrazination products with pharmacological activity were obtained. In vitro, the hydrazination products exhibited a better anti-cancer activity compared with the diazotization products. Further mechanistic studies showed that compound 3ae inhibits cell migration and tubulin aggregation in T-24 cells, thereby leading to cell apoptosis.

Substrates are directly oxidized at the anode without using any metal catalyst and oxidant to obtain a series of nitrogen heterocyclic compounds, including benzimidazoles and quinolinones. These compounds are highly tolerant to various functional groups and heterocycle-containing substrates. In addition, natural alkaloids, such as rutaecarpine and deoxyvasicinone, can be synthesized by this method.

A photocatalyst-free visible-light-promoted sulfenylation of quinoxalinones with thiols via cross-dehydrogenative coupling was developed. This protocol allowed the direct formation of diverse 3-sulfenylquinoxalin-2(1H)-ones under metal- and catalyst-free conditions and using air (O2) as an oxidant. Furthermore, a range of readily accessible thiols and quinoxalin-2(1H)-ones was applied in this coupling, resulting in an attractive process of accessing 3-substituted quinoxalinones.

Building new biological molecules is challenging. Herein, imidazo[1,2-c]thiazoles were synthesized as a new class of heterobicyclic analogs through Pd-catalyzed cascade bicyclization from isonitriles with thioamides. The bicyclic scaffolds were constructed by inserting three molecules of isonitrile into two molecules of thioamide and then cyclizing them in a one-pot procedure. In vitro antitumor studies of these new compounds were conducted by using the MTT assay, and compound 3c showed excellent inhibitory effects against HepG2 at 7.06 ± 0.68 μM.

The kidney is a typical organ undergoing age and injury. Hyperoside is reported to be useful for preventing aging induced by D-galactose (D-gal). However, therapeutic mechanisms remain unclear. We thereby aimed to verify whether hyperoside, compared to vitamin E (VE), could alleviate renal aging and injury by regulating autophagic activity and its related signaling pathways. In vivo, rats were administered with either hyperoside or VE after renal aging modeling induced by D-gal. Changes in renal aging and injury markers, autophagic activity and AMPK-ULK1 signaling pathway in the kidneys were analysed. In vitro, the NRK-52E cells exposed to D-gal were used to investigate regulative actions of hyperoside and VE on cell viability, renal tubular cellular aging markers, autophagic activity and its related signaling pathways by histomorphometry, immunohistochemistry, immunofluorescence, lentiviral transfection and Western blot. Aging and injury in the kidneys and renal tubular cells induced by D-gal were ameliorated by hyperoside and VE. Hyperoside and VE inhibited autophagic activity through mTOR-independent and AMPK-ULK1 signaling pathways. Hyperoside, as a component of phytomedicine similar to VE, attenuated renal aging and injury induced by D-gal via inhibiting AMPK-ULK1-mediated autophagy. This study provides the first evidence that hyperoside contributes to the prevention of age-associated renal injury.

A porous organic polymer (POL-Xantphos) was synthesized and employed as a heterogeneous ligand for selective hydrosilylation of alkynes. It exhibits high selectivity and catalytic efficiency toward a broad range of alkynes. Owing to the confinement effect of the micropore structure, POL-Xantphos was far superior to the monomeric Xantphos ligands in controlling the selectivity. By performing hydrosilylation in a flow reactor system, separation and regeneration of the Ni/POL-Xantphos catalyst are easily achieved without any loss in selectivity or activity.

A Co(acac)2 /POL-Xantphos@10PPh3 -catalyzed hydrosilylation of unsymmetrical internal alkynes with Ph2 SiH2 has been developed for the synthesis of highly selective syn-α-vinylsilane products. Furthermore, terminal alkynes were also used and gave the products with excellent regioselectivity and a wide functional group tolerance. Because this porous organic polymer combines the selectivity and activity merits of Xantphos with the stability advantage derived from the high concentration of PPh3 , the Co(acac)2 /POL-Xantphos@10PPh3 can be recycled multiple times without loss of activity and selectivity. This heterogeneous catalyst is expected to find promising applications in industrial synthesis.

A new method for the synthesis of multisubstituted guanidines through tandem intermolecular insertion of isonitriles with un­activated amides has been developed. In this study, isonitriles could be used not only as reaction materials but also as the source of amines.

A concise strategy for the synthesis of substituted 4-acylpyrazole derivatives from N-propargylic sulfonylhydrazones and diaryliodonium salts has been developed. The pyrazole derivatives are formed through a five-step cascade sequence that includes intramolecular cyclization, hydroxylation, elimination, copper-catalyzed aerobic oxidation, and intramolecular rearrangement.

Ethnopharmacological relevance Huangkui capsule (HKC), extracted from Abelmoschus manihot (L.) medic (AM), as a patent proprietary Chinese medicine on the market for approximately 20 years, has been clinically used to treat chronic glomerulonephritis. Renal fibrosis has been implicated in the onset and development of diabetic nephropathy (DN). However, the potential application of HKC for preventing DN has not been evaluated. Aim of the study This study was designed to investigate the efficacy and underlying mechanisms of HKC combined with metformin (MET), the first-line medication for treating type 2 diabetes, in the treatment of renal interstitial fibrosis. Materials and methods A rat model of diabetes-associated renal fibrosis was established by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg) combined with a high-fat and high-glucose diet. The rats were randomly divided into five groups: normal control, DN, HKC (1.0 g/kg/day), MET (100 mg/kg/d), and HKC plus MET (1.0 g/kg/day + 100 mg/kg/d). Following drug administration for 8 weeks, we collected blood, urine, and kidney tissue for analysis. Biochemical markers and metabolic parameters were detected using commercial kits. Histopathological staining was performed to monitor morphological changes in the rat kidney. High-glucose-induced human kidney HK-2 cells were used to evaluate the renal protective effects of HKC combined with MET (100 μg/mL+10 mmol/L). MTT assay and acridine orange/ethidium bromide were used to examine cell proliferation inhibition rates and apoptosis. Immunofluorescence assay and Western blot analysis were performed to detect renal fibrosis-related proteins including Klotho, TGF-β1, and phosphorylated (p)-p38. Results Combination therapy (HKC plus MET) significantly improved the weight, reduced blood glucose (BG), blood urea nitrogen (BUN), total cholesterol (T-CHO), triglycerides (TG), low-density lipoprotein (LDL) and increased the level of high-density lipoprotein (HDL) of DN rats. Combination therapy also significantly reduced urine serum creatinine (SCR) and urine protein (UP) levels as well as reduced the degrees of renal tubule damage and glomerulopathy in DN rats. Combination therapy ameliorated renal fibrosis, as evidenced by reduced levels of alpha-smooth muscle actin and fibronectin and increased expression of E-cadherin in the kidneys. Moreover, HKC plus MET alleviated the degree of DN in part via the Klotho/TGF-β1/p38MAPK signaling pathway. In vitro experiments showed that combination therapy significantly inhibited cell proliferation and apoptosis and regulated fibrosis-related proteins in high-glucose (HG)-induced HK-2 cells. Further studies revealed that combination therapy suppressed cell proliferation and fibrosis by inhibiting the Klotho-dependent TGF-β1/p38MAPK pathway. Conclusions HKC plus MET in combination suppressed abnormal renal cell proliferation and fibrosis by inhibiting the Klotho-dependent TGF-β1/p38MAPK pathway. Collectively, HKC combined with MET effectively improved DN by inhibiting renal fibrosis-associated proteins and blocking the Klotho/TGF-β1/p38MAPK signaling pathway. These findings improve the understanding of the pathogenesis of diabetes-associated complications and support that HKC plus MET combination therapy is a promising strategy for preventing DN.

A simple and efficient Cu-catalyzed decarboxylative/click reaction for the preparation of 1,4-disubstituted 5-arylselanyl-1,2,3-triazoles from propiolic acids, diselenides, and azides has been developed. The mechanistic study revealed that the intermolecular AAC reaction of an alkynyl selenium intermediate occurred. The resulting multisubstituted 5-seleno-1,2,3-triazoles were tested for in vitro anticancer activity by MTT assay, and compounds 4f, 4h, and 4p showed potent cancer cell-growth inhibition activities.

An efficient electrochemical transformation of structurally diverse sulfonyl hydrazides and thiols into thiosulfonates in the presence of ammonium iodide as redox catalyst and electrolyte in acetonitrile at ambient temperature is reported. Transition metal- and oxidant-free conditions are the striking features of this protocol. The in vitro cytotoxicity of all compounds is evaluated by MTT assay against four human cancer cell lines. The results reveal that 3ac and 3ag exhibit potential inhibitory activity against tumor cells. Furthermore, 3ag inhibits cell migration ability and tubulin polymerization in T-24 cells, leading to cell cycle arrest and apoptosis.

Herein, a transition metal-free and efficient cascade reaction of ynones with 2-methylbenzimidazoles under mild conditions has been revealed. This cascade reaction involved a Michael addition/intramolecular cycloaddition/dehydration and provided the desired benzo[4,5]imidazo[1,2-a]pyridines in moderate to good yield. Furthermore, three benzo[4,5]imidazo[1,2-a]pyridines (3d, 3i, and 3q) exhibited good activities against Hep-G2 (human liver cancer), T-24 (human bladder cancer cell), and SK-OV-3 (human ovarian cancer) cell lines with IC50 values in the range of 8.05–10.67 μmol L−1. To investigate the mechanism of the effective inhibition of cell growth, further studies, including cell cycle analysis, apoptosis ratio detection, measurement of Ca2+ generation, ROS, mitochondrial membrane potential assay, and caspase-3/9 activation, were carried out on compound 3i.

A new type of phosphorus-doped porous organic polymer (POP) has been readily synthesized through a Heck reaction, which could be used not only as a support but also a ligand for palladium nanoparticles. The dual-functional material supported palladium nanocatalyst was used for the efficient and chemoselective hydrogenation of varieties of nitroarenes and α,β-unsaturated compounds, as well as for the synthesis of indoles from 2-nitrophenylacetonitrile under 1 atm hydrogen in green solvents at room temperature. No obvious aggregation and loss of catalytic activity of the new nanocatalyst were observed after 10 runs in the reaction.

A new strategy for the synthesis of (E)-4-benzylidene-4,5-dihydro-1H-pyrazoles through tandem intermolecular addition–intramolecular cyclization of N-propargylic sulfonylhydrazones has been developed. In this study, we firstly report that N-propargylic sulfonylhydrazones react with electrophilic reagents to afford 4-substituted pyrazole derivatives.

C-centered radical cyclization under electrochemical conditions is a feasible strategy for constructing cyclic structures. Reported herein is the electrochemical synthesis of highly functionalized 1-naphthols using alkynes and 1,3-dicarbonyl compounds by (4 + 2) annulation of C-centered radical. Electrolysis was conducted with Cp2Fe as redox catalyst, thereby eliminating the use of oxidants and transition-metal catalysts. The synthesized 1-naphthol compounds showed good antitumor activity in vitro, and further studies indicated that compound 3bl induced tumor cell apoptosis.

An expeditious strategy for the synthesis of pyrazolo[5,1-a]isoquinolines has been developed. The tricyclic scaffolds are formed through a four-step cascade sequence, including copper(II)-catalyzed regioselective bicyclization, nucleophilic addition of H2O, aerobic oxidation, and aromatization through eliminating a molecule of TsH. The synthetic utility of this method is demonstrated through the synthesis of a potential CDC25B inhibitor.

In addition to being associated with energy supply, lipid droplets (LDs) play vital roles in many other important physiological and some pathological processes. Fluorescent probes are useful tools for studying the biological functions of LDs. In this study, we develop three new highly fluorescent LD-specific bioprobes, which can be excited by one- and two-photon, with favorable biocompatibility. They have little crosstalk with some commonly used commercially-available green- and red-emissive probes, such as BODIPY 493/503, MitoTracker Red CMXRos (MTR) and LysoTracker Red DND-99 (LTR), thus allowing the simultaneous multicolor imaging. Notably, one of the probes, BIP-1, has superior photostability and allows excellent 3D imaging of cellular LDs. BIP-1 can be used to monitor the number and morphological changes of LDs, and the interactions of LDs with other organelles (e.g. mitochondria) under specific physiological conditions (e.g. starvation). Overall, BIP-1 is a promising alternative fluorescent bioprobe for live-cell LD-specific imaging and long-term tracking during LD-related research.

Heterogeneous, metal, single-site catalysts often exhibit higher catalytic performance than other catalysts because of their maximized atom efficiency of 100 %. Reported herein is a precoordination/solvothermal polymerization strategy to fabricate a stable mononuclear Pd-metalized porous organic polymer catalyst (Pd@POP). Pd@POP was easy to use in regioselective organic reactions because the internal structure of this Pd@POP can be easily modified. The catalyst was used to solve the intractable regioselectivity problems of Heck reactions. Pd@POP-9 can efficiently activate the ends of olefins, thereby leading to high selectivity for substitution at the external position. To understand the reason underlying the high selectivity and activity of the catalyst, the systemic characterization of Pd@POP-9 and density-functional theory calculations were conducted. This Heck reaction is the first to be catalyzed by a recyclable mononuclear metal catalyst with unprecedented catalytic activity and regioselectivity.

An unexpected cyclization of thioamides with p-quinone methides promoted by acridinium salt under the irradiation of visible light furnished 1,2,4-dithiazoles in moderate to good yields. In addition, the reaction of the obtained 1,2,4-dithiazoles with isocyanides offered a new entry for the synthesis of thiazol-5(4 H)-imines in moderate yields.