Search

Porous carbon materials have attracted much attention in the field of organic synthesis in recent years, due to their tunable properties, excellent catalytic activity and stability. Biomass-based carbohydrates emerge as an ideal precursor for the generation of these materials owing to their renewability, low cost, non-toxicity and high content of functional groups. Thus, carbon materials prepared from carbohydrates is of considerable importance for the sustainable development of organic chemistry. The present review not only summarizes recent examples of carbohydrate-derived porous carbon material-catalyzed organic reactions including the oxidation, hydrogenation, cross-coupling, esterification and condensation reactions, but also introduces the preparation and functionalization strategies of these materials. Furthermore, the challenges and opportunities of organic synthesis over these sustainable materials have also been addressed. This review will stimulate further research on exploring novel carbohydrate-derived porous carbon materials and new sustainable organic synthetic processes over these materials.

ZIF-derived metal/N-doped porous carbon have emerged as efficient heterogeneous catalysts in organic reactions, due to controllable 3D structure, uniformly dispersed metal sites, tunable metal–support interactions and superior catalytic performance.

A Fe–FeOx@NC catalyst with N-doped carbon encapsulated Fe–FeOx nanoparticles has excellent performance in the synthesis of quinazolines.

BackgroundPediatric intracerebral hemorrhage (pICH) remains a considerable cause of mortality. This study aimed to explore functional prognosis predictors in Chinese patients with pICH and attempted to develop and validate a nomogram for estimating individual risk probability of short-term unfavorable functional prognosis.MethodsA retrospective case-control study through records reviewing was conducted, non-neonate patients with nontraumatic pICH discharged from the Children’s Hospital of Fudan University between January 2012 and December 2021 were all originally included. The primary outcome was unfavorable functional prognosis at 3 months post pICH defined as a score of 3–6 as measured using the modified Rankin Scale (ranging from 0 [asymptomatic] to 6 [death]). Multivariate logistic regression analysis was performed to screen prognosis predictors, a prediction model-based nomogram was developed. Internal validation was assessed and quantified as receiver operating characteristic (ROC) curve and bootstrapped calibration curve.ResultsA total of 269 pICH patients were enrolled, the median age was 57.2 months (interquartile range, 5.4–115.1), and 157 (58.4%) patients were male. The median follow-up time was 3.2 months (interquartile range, 2.8–3.6), 112 (41.6%) patients had unfavorable functional outcome. Cerebral vascularmalformation as etiology, modifiedGlasgow Coma Score on admission,brainstem location, and intracerebral hemorrhage volume aspercentage of total brain volume were identified as functional prognosis predictors. A nomogram was established comprising these four predictors, abbreviated to MGBP, the area under the ROC curve of the nomogram was 0.827 (95% Confidence Interval, 0.778–0.877) with good calibration (P=0.803 for the Spiegelhalter’s Z-test).ConclusionsThe MGBP nomogram is the first model developed and validated in a consecutive cohort to predict 3-month unfavorable functional prognosis post nontraumatic pICH in Chinese children, which may provide clinicians with a potentially effective approach for early prediction and timely management of pICH.

A green and scalable strategy has been developed for the synthesis of lignin-derived Zn single atom/N-codoped porous carbon (LCN@Zn-SAC) containing similar ZnNx sites with carbonic anhydrases. This catalyst exhibits superior activity on the α-alkylation of ketones with alcohols via borrowing hydrogen strategy (TON up to 15 h−1) than most of previously reported works. The dehydrogenation of benzyl alcohol is the rate-determining step based on kinetic experiment results. According to experimental and theoretical calculation results, Zn electron density is inversely proportional to reaction energy barriers, because Zn sites with less positive charge (ZnN4 and ZnN3C) in Zn-SACs display better borrowing hydrogen ability than other Zn sites. Furthermore, this catalyst can be recycled by simple centrifugation, which can be reused at least 8 runs with no obvious lose in activity. To the best of our knowledge, this is the first example of non-noble metal-SAC-catalyzed α-alkylation via borrowing hydrogen strategy.

N-Heterocycles, such as pyrroles, pyrimidines, quinazolines, and quinoxalines, are important building blocks for organic chemistry and the fine-chemical industry. For their synthesis, catalytic borrowing hydrogen and acceptorless dehydrogenative coupling reactions of alcohols as sustainable reagents have received significant attention in recent years. To overcome the problems of product separation and catalyst reusability, several metal-based heterogeneous catalysts have been reported to achieve these transformations with good yields and selectivity. In this Minireview, we summarize recent developments using both noble and non-noble metal-based heterogeneous catalysts to synthesize N-heterocycles from alcohols and N-nucleophiles via acceptorless dehydrogenation or borrowing hydrogen methodologies. Furthermore, this Minireview introduces strategies for the preparation and functionalization of the corresponding heterogeneous catalysts, discusses the reaction mechanisms and the roles of metal electronic states, and the influence of support Lewis acid-base properties on these reactions.

A facile, gram-scale and sustainable approach has been established for the synthesis of single-atomic-site iron on N-doped carbon (FeSA@NC-20A) via the pyrolysis of aniline modified FeZn-ZIFs, in which the synthesis of zeolitic imidazolate frameworks (ZIFs) can be accomplished in water at room temperature, and no acid etching is required. The as-synthesized catalyst exhibits better performance on the chemoselective hydrogenation of nitroarenes with a broad substrate scope (turnover frequency (TOF) up to 1,727 h−1, 23 examples) than most of previously reported works. Based on high-angle annular dark field scanning transmission microscopy (HAADF-STEM) images in combination with X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), electron spin resonance (ESR), and Mossbauer spectroscopy, Fe is dispersed as single atoms via forming FeNx (x = 4–6). This work not only determines the active sites of FeSA@NC-20A for hydrogenation (FeN4), but also proposes tentative pathways for both N-H activation of hydrazine and the reduction of nitroarene on FeN4 site, both of which are the key steps for the hydrogenation of nitroarenes. In addition, this catalyst shows excellent stability, and no significant activity degradation is observed when recycling for 10 times or restoring in air for 2 months.

Organosilicon compounds play an important role in the fields of materials science, pharmacy, and organic synthesis. The development of effective approaches for the preparation of these compounds have also become a research focus in organic synthesis. In recent years, free radical synthesis of organosilicons has been vigorously developed, which generally has the advantages of milder synthesis conditions, higher yields and selectivity, and free of precious metal catalysts compared with traditional strategies. This article reviews research progresses in the synthesis of organosilicon compounds by free radical pathways since 2016. In most cases, the radical silylation is achieved based on the reaction of silyl radicals, which are triggered by four routes including peroxide, transition-metal-induced peroxide decomposition, alkali, photocatalysis. The alkyl radicals can also initiate the radical silylation for the generation of C(sp3) Si bonds.

Objective To investigate the expression and significance of human neutrophil lipocalin (HNL) and neutrophil CD64 (nCD64) in prostatic fluid of chronic prostatitis patients with different infection degrees. Methods One hundred and seventy-eight patients with chronic prostatitis admitted to the Affiliated Ethnic Hospital of Guangxi Medical University from February 2017 to October 2019 were selected as the research objects. According to whether they were infected with bacteria, the patients were divided into chronic prostatitis/chronic pelvic pain syndromes group (CP/CPPS group, n=40) and chronic bacterial prostatitis group (CBP group, n=138). According to National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) score, CBP group was divided into mild group (n=65), moderate group (n=46) and severe group (n=27), and another 40 healthy people were selected as control group. Age, body mass index (BMI), course of disease, white blood cell (WBC), and NIH-CPSI score were recorded and analyzed. The expression level of HNL in prostatic fluid was detected by enzyme linked immunosorbent assay (ELISA). The expression level of nCD64 in prostatic fluid was detected by flow cytometry. Pearson correlation was used to analyze the correlation between both HNL and NCD64 levels and NIH-CPSI score in the CBP group. Logistic regression analysis was used to analyze the influencing factors of CBP and CP/CPPS. ROC curve was used to evaluate the diagnostic value of HNL and nCD64 for CBP. Results Compared with the control group, WBC, HNL and nCD64 levels in CP/CPPS group, CBP group and its subgroups were significantly increased (P0.05), but NIH-CPSI score of moderate group was higher than that of mild group, and that of severe group was higher than that of moderate group and mild group (P

An efficient, sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons (Co@NCs) via pyrolysis of aniline-modified ZIFs, has been demonstrated. Aniline can coordinate and absorb on the surface of ZIF (ZIF-CoZn3-PhA), accelerate the precipitation of ZIFs, thus resulting in smaller ZIF particle size. Meanwhile, the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles, and increases nitrogen content of the catalyst. Because of these properties of Co@NC-PhA-3, the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions. According to our experimental and computational results, a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established, in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF. Moreover, the formation and release of active oxygen species in CoNx sites are reinforced by the electronic interaction between Co nanoparticles and CoNx.

Suzuki coupling reaction is a widely practiced protocol in organic synthesis for the formation of C–C bonds. The conventional process for this reaction usually involves high temperatures and noble metals. Hence, the development of a green, cost-effective photocatalytic system is an attractive and challenging strategy for the reaction. Here, we report a modified palladium-free Co-doped BiOCl/Ce-doped Bi2O2CO3 (CBCB) composite, which shows high photocatalytic activity under white LED irradiation. At room temperature, an excellent yield (91%) of the desired cross-coupling product biphenyl was obtained in environmentally friendly solvents. Density functional calculations, together with the experimental results, show that the presence of Co and Ce ions results in the appearance of some impurity levels near the Fermi level of pure BiOCl and Bi2O2CO3, which decreases their forbidden bandwidth, thus ensuring higher light absorption and superior electronic conductivity. Moreover, the intimate interfacial contact between Co-doped BiOCl and Ce-doped Bi2O2CO3 planes has a significant impact on the separation and transfer of photoinduced charge carriers, which ultimately leads to a remarkable increase in visible-light-driven photocatalytic activity.

Hydrogen auto-transfer (HAT) or borrowing hydrogen (BH) methodology which combines dehydrogenation, intermediate reaction and hydrogenation, is recognized as an excellent strategy for one-pot synthesis from an economic and environmental point of view. Although much effort has been made on the development of catalysts for HAT reactions, harsh conditions, external base or large amounts of noble metals are still required in most reported catalysis systems, and thus the exploration of a highly efficient and recyclable heterogeneous catalyst remains meaningful. In this work, a novel bimetallic catalyst, Fe10Pd1/NC500 derived from bimetallic MOF NH2-MIL-101(Fe10Pd1), has been prepared, and the catalyst exhibits superior catalytic performance for the N-alkylation of amines with alcohols via a hydrogen auto-transfer methodology. High yields of the desired products were achieved at 120 °C with an alcohol/amine molar ratio of 2 : 1 and required no external additive or solvent. A distinct enhancement in catalytic performance is observed when compared with monometallic catalysts, which can be ascribed to the “synergistic effects” inside the bimetallic alloys. The N-doped carbon support has been revealed to provide the necessary basicity which avoids the requirement of an external base. Moreover, a wide substrate range and remarkable reusability have been shown by Fe10Pd1/NC500, and this work highlights new possibilities for bimetallic catalysts applied in sustainable chemistry.

Nitriles are synthetic intermediates of great importance, so it is significant and appealing to develop novel approaches for the green synthesis of these compounds. Compared with other synthetic strategies, the ammoxidation of alcohols over heterogeneous catalysts emerges as a sustainable process for the preparation of nitriles owing to its atom and step economy, and the use of cheap and sustainable raw materials and recyclable catalysts. In this review, we summarized the latest progress in developing heterogeneous catalysts to achieve the transformation of alcohols into nitriles. Furthermore, this review not only introduces the preparation and functionalization strategies of heterogeneous catalysts, but also discusses the reaction mechanism and the roles of heterogeneous catalysts in these reactions.

A metal-free oxidative dehydrogenation of N-heterocycles utilizing a nitrogen/phosphorus co-doped porous carbon (NPCH) catalyst is reported. The optimal material is robust against traditional poisoning agents and shows high antioxidant resistance. It exhibits good catalytic performance for the synthesis of various quinoline, indole, isoquinoline, and quinoxaline 'on-water' under air atmosphere. The active sites in the NPCH catalyst are proposed to be phosphorus and nitrogen centers within the porous carbon network.

To solve the inherent defects of laccase, the first iron single-atom anchored N-doped carbon material (Fe1@CN-20) as a laccase mimic was disclosed. The FeN4 structure of this material can well mimic the catalytic activity of laccase. Although Fe1@CN-20 has a lower metal content (2.9 wt.%) than any previously reported laccase mimics, it exhibits kinetic constants comparable to those of laccase, as its Km (Michaelis constant) and Vmax (maximum rate) are 0.070 mM and 2.25 µM/min respectively, which are similar to those of laccase (0.078 mM, 2.49 µM/min). This catalyst displays excellent stability even under extreme pH (2-9), high temperature (100 oC), strong ionic strength (500 mM of NaCl), high ethanol concentration (volume ratio 40%) and long storage time (2 months). Additionally, it can be reused for at least 7 times with only a slight loss in activity. Therefore, this material has a much lower price and better stability and recyclability than laccase, which has been applied in the detection and degradation of a series of phenolic compounds. In the detection of adrenaline, Fe1@CN-20 achieved a detection limit of 1.3 µM, indicating it is more sensitive than laccase (3.9 µM).

The reaction mechanisms of Rh-catalyzed regioselective hydrothiolation of the allyl amine employing four bidentate phosphine ligands are investigated with DFT calculations. The free energy profiles of anti-Markovnikov and Markovnikov pathways arising from different alkene insertion types are computed to elucidate the ligand-controlled regioselectivity. For 1,2-bis(diphenylphosphino)benzene (dppbz) and 1,3-bis(diphenylphosphino)propane (dppp) ligands with small nature bite angle (βn ≤ 86°), the anti-Markovnikov pathway that features the 1,2-alkene insertion into Rh-H bond is favored by 2 ˜ 4 kcal/mol in barriers of elementary steps. While for 1,4-bis(diphenylphosphino)butane (dppb) and bis(2-diphenylphosphinophenyl)ether (DPEphos) ligands with large nature bite angle (βn ≥ 99°), the Markovnikov pathway with 1,2-alkene insertion into Rh-S bond is preferential by 2 ˜ 7 kcal/mol in barriers. The P-Rh-P bite angle is a reliable predictor and regulator of the regioselectivity of reaction as evidenced by good correlations between reaction barrier and P-Rh-P bite angle. Smaller P-Rh-P bite angle in TSs is generally found for small nature bite angle ligand dppbz and dppp in preferential anti-Markovnikov pathway, while TSs with larger P-Rh-P bite angle are favored by large nature bite angle ligand DPEphos and dppb. Larger difference in P-Rh-P bite angles of TSs between Markovnikov and anti-Markovnikov pathway generally leads to the greater disparity in barrier heights of two pathways, and hence greater regiodivergency of reaction.

Herein, we describe pH-responsive Pickering emulsions stabilized by a sodium carboxylate-derived selenium surfactant (C10-Se-C10·(COONa)2) in combination with positively charged alumina nanoparticles. Unlike other bola-type carboxylate surfactants (e.g., disodium eicosanoate), C10-Se-C10·(COONa)2 is soluble in water with a low Krafft temperature (36.1 °C). The emulsions are sensitive to pH variations, and efficient demulsification can be achieved by a pH trigger. The carboxylic sodium group in the C10-Se-C10·(COONa)2 structure can be reversibly cycled between its anionic and nonionic states (carboxylic acid), resulting in a pH-controlled electrostatic attraction between the surfactant and alumina. The Pickering emulsion can be reversibly switched between "on" (stable) and "off" (unstable) states by pH at least four times. Compared with the emulsions stabilized by specially synthesized stimuli-responsive particles or surfactants, the method reported here is much easier to implement and requires very low concentrations of the surfactant and nanoparticles, with potential applications in the fields of biomedicine, drug delivery, and cosmetics.

A highly efficient bimetallic nanoparticles (BMNPs) catalyst was reported, Pd1Ni4/AC, consisting of Pd1Ni4 BMNPs supported on active carbon, shown excellent catalytic performance and stablity in hydrodeoxygenation (HDO) of vanillin. HDO of vanillin and various aldehydes with high efficiency and selectivity could be achieved at low H2 pressure (2 bar) under mild conditions in the presence of the BMNPs catalyst, no obvious decrease on catalytic performance was observed after eight cycles. The superior catalytic performance of the Pd1Ni4/AC catalyst was mainly attributable to the synergetic electronic effect between Pd and Ni, which showcased the great potential of BMNPs in the catalysis field.

A cobalt catalyst derived from a unique core–shell structure based on hollow ZIF-8 and ZIF-67 (ZIF-67@ZIF-8) is prepared, which exhibits excellent catalytic efficiency for the synthesis of nitriles from alcohols in water under mild conditions (1 atm O2, 50 °C) owing to its large BET surface area, high pore volume, high basicity and hydrophilicity.

UiO-66(Ce)-encapsulated ruthenium nanoparticles (Ru@UiO-66(Ce)) was designed and used for dehydrogenation of primary amines to nitriles in water without any hydrogen acceptors and additives. Introduction of metal Ru to UiO-66(Ce) contributes to the formation of Lewis acid–base pairs on the catalyst owing to the metal–support interaction, acting as active sites for activation of amines and transfer of hydrogen. Ab initio calculation results further confirm the roles of Lewis acid–base pairs in the reaction.

A newly developed template protection-sacrifice (TPS) strategy is developed for the synthesis of hollow yolk–shell Co@CN with a large surface area and high pore volume. The catalyst exhibits excellent catalytic efficiency in base-free oxidative esterification of 5-hydroxymethylfurfural under mild conditions with excellent selectivity at a high concentration (2 M) of the reactant.

A concerted one-step addition mechanism for anti-Markovnikov hydrothiolation in [Hmim]Br catalyzed thiol–ene reactions is revealed by a combined DFT and experimental study for the first time. This special mechanism represents a typical “ionic liquid effect”, which is driven by the directional hydrogen bond and π+–π interactions that conjoin the substrates and [Hmim]Br into a prereactive complex. The transition state is stabilized and characterized by a planar 6-membered ring containing HBr and four substrate atoms at the reaction site. The concerted addition mechanism and the special structural feature of the TS render the reaction regiospecific, i.e. only the anti-Markovnikov product is produced. When the styrene is replaced by aliphatic alkenes, the substrates are loosely bound with the ionic liquid. As a result, the prereactive complex is destabilized and the reactivity drops significantly.

A newly developed chemoselective reaction of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes has been disclosed. The chemistry, in which non-toxic water and recyclable iron-based metal-organic frameworks are employed as the solvent and catalyst, respectively, provides an efficient approach for the generation of N-arylsulfonamides, which are widely present in biologically active compounds and drugs, rendering this methodology attractive to both synthetic and medicinal chemistry.

A strategy for the synthesis of coumarin derivatives via visible-light photoredox catalysis has been developed using fac-Ir(ppy)3 as the photocatalyst under mild conditions. Trifluoromethanesulfonyl chloride is utilized as the trifluoromethylation reagent, which is cheap and readily available. Aryl alkynoates are trifluoromethylated, then undergo a radical cyclization and a cascade ester migration to generate target products.

A highly selective anti-Markovnikov hydroboration reaction of alkenes with bis(pinacolato)diboron catalyzed by 4-cyanopyridine has been described. This strategy provides an efficient, practical and environmentally benign protocol for the construction of alkylboronates in moderate to good yields under metal-free conditions. A radical mechanism proceeding via a 4-cyanopyridine-ligated boryl radical was proposed.

The aerobic oxidative coupling of alkynes and phosphite esters can be catalyzed by Cu/Cu2O nanoparticles supported on Nb2O5 (Cu/Cu2O@Nb2O5) to efficiently afford alkynylphosphonates. The catalyst can be reused by filtration and reduction. According to the results of control experiments and characterization data, the supporter Nb2O5 can reduce the electronic density of Cu and absorb the phosphite esters due to its strong Lewis acid sites, which may enhance the reaction efficiently.