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BACKGROUND: Tobacco stalk, the main waste from tobacco planting, was used as raw material to produce levulinic acid, one of the most important platform chemicals. It was reported that steam explosion was an efficient method to treat lignocellulose to hydrolyze the hemicellulose component. Oxidation treatment combined with catalysis of Al2(SO4)3 proved to be efficient for the conversion of cellulose to levulinic acid in our recent report. Here, tobacco stalk was first treated by steam explosion, and then the solid residue was oxidized and converted to levulinic acid in the presence of Al2(SO4)3. RESULTS: A xylo‐oligosaccharide yield of 6.6 g 100 g−1 was obtained from tobacco stalk via steam explosion. 15.4 g 100 g−1 (39.6 mol%) yield of levulinic acid was obtained from oxidized tobacco stalk in water at 180 °C in 5 h using Al2(SO4)3 as a catalyst. As high as 20.8 g 100 g−1 (53.5 mol%) yield of levulinic acid can be obtained using NaCl as a co‐catalyst. CONCLUSION: Steam explosion was efficient for the depolymerization of the hemicellulose component of tobacco stalk to xylo‐oligosaccharide. A simple salt of Al2(SO4)3 showed good catalytic activity for conversion of oxidized tobacco stalk to levulinic acid. Nicotine in tobacco stalk promoted the formation of lactic acid. Thus, the yield of levulinic acid decreased in the presence of nicotine. NaCl enhanced the catalytic performance of Al2(SO4)3. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by‐products of agricultural biomass in crop‐producing filed, valorization of corn straw has attracted considerable attention. In this study, a two‐step depolymerizing strategy of high‐pressure CO2−H2O pretreatment and oxidation‐hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high‐pressure CO2−H2O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6 h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production. [ABSTRACT FROM AUTHOR]

This article discusses a case report of a patient with epidermodysplasia verruciformis (EV), a rare genetic disorder that leads to the development of cutaneous squamous cell carcinoma (cSCC) in situ. The traditional treatment for EV and cSCC in situ is surgical excision, but this can result in disfigured or dysfunctional outcomes. The article presents a successful alternative treatment using 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT), which showed satisfactory results in flattening and shrinking the cSCC in situ lesions. ALA-PDT is a noninvasive treatment that selectively targets abnormal skin tissues without damaging healthy tissues. The article suggests that ALA-PDT may be a promising therapy for multiple cSCC in situ and can potentially prevent cancer development and progression. [Extracted from the article]

In this review, the research progress on catalytic conversion of glycerol to lactic acid or lactate esters and the reaction mechanisms with different catalysis systems are summarized. Both homogeneous catalysts, including inorganic bases and metal complexes, and heterogeneous catalysts, including metal oxides, molecular sieves, polyoxometalates and noble and non‐noble metals, are discussed. In particular, the influence of catalyst components, the physical and chemical properties of the catalysts and additives and solvents on the catalytic performances are highlighted. In comparison, nano‐metal particles or bimetal catalysts could achieve good catalytic performance, in which the alloy and synergistic effects might form under certain conditions. For further improvement of the sustainable transformation of glycerol to lactic acid or lactate esters, attention should still be paid to rational design of novel cost‐effective, high‐efficiency and green catalytic systems. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A convenient and efficient copper‐catalyzed three‐component difluoromethylation‐peroxidation of alkenes with commercially‐available sodium difluoromethanesulfinate and tert‐butyl hydroperoxide has been developed. This protocol enables the synthesis of a variety of β‐difluoromethyl peroxides under mild conditions. Versatile synthetic transformations of the difluoromethyl peroxides have also been explored. [ABSTRACT FROM AUTHOR]

A facile protocol for the synthesis of 1,3,4‐oxadiazoles has been developed by [4+1] cyclization of α‐CF3 carbonyls and hydrazides. This method employs readily available starting materials and the reaction conditions are simple and mild. Synthetic transformation of the 1,3,4‐oxadiazole product has also been investigated. [ABSTRACT FROM AUTHOR]

The synthesis and photophysical properties of fluorescent pyrazolo[1,5‐a]pyrimidines (PPs) are explored. An array of 5,7‐disubstituted fluorescent PPs are prepared selectively by using β,β‐difluoro peroxides as the 1,3‐bis‐electrophiles. The synthesized PPs display a fairly significant stokes shift (up to 211 nm) and a large window of tunable emission wavelength that covers most of the visible spectrum (400 nm to 800 nm). Theoretical calculation indicates that the distinguished variation of intramolecular charge transfer (ICT) ability upon the varied substituents is responsible for the color‐tunable fluorescence emission. [ABSTRACT FROM AUTHOR]

The reasonable control of the dispersion of noble metals is an important topic for heterogeneous catalysts. In this manuscript, PdCu/C, AuCu/C and PdAuCu/C were prepared by the galvanic reduction method to ensure that Pd and Au follow the distribution of Cu nanoparticles. The catalysts were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy‐dispersive spectrometer elemental mappings and lines scans. Both the Pd and Au had very high dispersion no matter whether they were introduced individually or simultaneously. The Pd and Au were distributed mainly on the Cu nanoparticles as evidenced by the energy‐dispersive spectrometer elemental mappings and lines scans. The reduction of 4‐nitrophenol was used as a model reaction for the prepared catalysts. PdCu/C and AuCu/C showed high activity for this reaction compared to the literature, and the activity could be further increased by the introduction of Pd and Au in an appropriate ratio at the same time. The normalized reaction rate reached 2.005 s−1 mM−1 for the PdAuCu/C‐2.0, in which the mole ratio of Pd to Au was 2.0. [ABSTRACT FROM AUTHOR]

The isoxazole skeleton is one of key structural motifs, which displays widespread applications in drugs, agriculture, and synthetic intermediates. Herein, we disclose the DABCO‐mediated [4+1] cycloaddition of β,β‐dihalo peroxides and sodium azide for synthesis of multisubstituted isoxazoles. The cycloaddition proceeds through the formation of N−C and N−O bonds. This method shows excellent regioselectivity and good scalability. [ABSTRACT FROM AUTHOR]

Mammalian target of rapamycin inhibitors have shown promising results in the management of kaposiform hemangioendothelioma (KHE). The purpose of this study was to present our experience involving sirolimus therapy for KHE. A retrospective study was conducted to review the medical documents of 26 patients with KHE who were treated with sirolimus at our hospital between March 2012 and December 2016. Fifteen males and 11 females manifested KHE in infancy with an average age of 2.9 ± 1.8 months. Multiple anatomical sites were involved. Four patients had multifocal lesions, while 22 patients had solitary lesions. Twenty‐five patients had Kasabach–Merritt phenomenon (KMP). Twenty patients completed sirolimus therapy in 28.3 ± 12.5 months. Nineteen KHE lesions reduced to small residuals with platelet counts reaching normal levels 3.7 ± 2.8 weeks after treatment; one KHE lesion had no response to therapy. One patient with multifocal lesions died due to a severe infection, although the patient had previously responded to sirolimus. Five patients remained in treatment and had good responses with normal platelet counts. Nineteen patients with anemia had normal hemoglobin levels after 3.5 ± 1.9 weeks of treatment. Mild side effects were observed. The median follow‐up time was 32 months (26–60 months), with no evidence of recurrences. Sirolimus was shown to be efficacious in the management of KHE with an average course of 28 months. The time‐to‐response was variable, with an average of 1 week. After 4 weeks of treatment, the platelet count and hemoglobin level had normalized. Multifocal KHE with KMP is more severe than solitary KHE. [ABSTRACT FROM AUTHOR]

Axial N‐O alcohols, which have two large carboline moieties connected to the axis were synthesized and used in catalytic enantioselective 1,2‐ and 1,4‐transfer hydrogenations of total 26 ketimines and β‐enamino esters. Excellent levels of enantioselectivity ranging from 91% to 99% were achieved by using catalyst (aS)‐(S)‐3,3′‐bis((S)‐2‐(hydroxymethyl)pyrrolidine‐1‐carbonyl)‐9,9′‐dimethyl‐9H,9′H‐[1,1′‐bipyrido[3,4‐b]indole] 2‐oxide. Interestingly, a mixture of (aS)‐(S)‐3,3′‐bis((S)‐2‐(hydroxymethyl)pyrrolidine‐1‐carbonyl)‐9,9′‐dimethyl‐9H,9′H‐[1,1′‐bipyrido[3,4‐b]indole] 2‐oxide and (aR)‐(S)‐3,3′‐bis((S)‐2‐(hydroxymethyl)pyrrolidine‐1‐carbonyl)‐9,9′‐dimethyl‐9H,9′H‐[1,1′‐bipyrido[3,4‐b]indole] 2‐oxide was also able to provide high enantioselectivities up to 95% that is the same as that using pure (aS)‐(S)‐3,3′‐bis((S)‐2‐(hydroxymethyl)pyrrolidine‐1‐carbonyl)‐9,9′‐dimethyl‐9H,9′H‐[1,1′‐bipyrido[3,4‐b]indole] 2‐oxide. A plausible catalytic mechanism was suggested and total four kinds of transition states (TS) including almost 60 TS structures were investigated using density functional theory (DFT) with different basis sets such as 6‐311G(2d,p). The predicted activation energy data are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

The cross‐coupling reactions of propargylic ethers with aryl Grignard reagents were achieved by using a copper catalyst. The method presents a practical and highly selective approach for the synthesis of propargyl derivatives by using ethyl salicylate as a directing leaving group, which highlights the advantages of its easy preparation and recovery. [ABSTRACT FROM AUTHOR]

Conversion of non‐edible lignocellulosic biomass into value‐added chemicals is of great significance and also particularly attractive. However, owing to the complexity and inertness, valorization of native lignocellulose remains to be quite challenging. Herein, catalytic oxidative cleavage of raw poplar sawdust was studied, mono‐aromatics and organic acid esters with 34.8 wt% and 27.4 wt% yield respectively were achieved over MoO2(acac)2 with molecular oxygen, which was suggested to be attributed to a prior cleavage of the carbohydrate fractions. This catalytic oxidation approach demonstrates the feasibility of transformation of raw woody biomass into valuable chemicals. [ABSTRACT FROM AUTHOR]