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A substrate-dependent, highly β-regioselective one-pot multicomponent 1,3-dipolar cycloaddition reaction of 3-methyl-4-nitro-5-isatylidenyl-isoxazoles with azomethine ylides (thermally generated in situ from ninhydrin and sarcosine) is reported for the first time, furnishing a library of biologically useful bispiro[oxindole-isoxazole-indandione] hybrids. Target novel and structurally complex compounds have been obtained in good yields and diastereoselectivities (up to 91% yield and 20 : 1 dr) with two adjacent spiro quaternary centres. Furthermore, the described method, which is different from our previous work of α-regioselective cycloaddition of 3-methyl-4-nitro-5-isatylidenyl-isoxazoles, is a highly β-regioselective cycloaddition. The newly synthesized compounds potently inhibited the proliferation of various cancer cell lines. The most potent compound 4ah could induce the apoptosis of K562 cells through a caspase-dependent and -independent pathway. [ABSTRACT FROM AUTHOR]

Achieved herein is a novel diversity‐oriented one‐pot multicomponent synthesis of polycyclic pyrrolidinyl‐dispirooxindoles 3. The key pyrrolidine forming reaction is the 1,3‐dipolar cycloaddition event of isatylidenyl‐chromanones 2 with azomethine ylides (thermally generated in situ from isatins and proline or thioproline). Products bearing four consecutive stereocenters consist of two oxindole moieties and a pyrrolidinyl core, including vicinal spiroquaternary stereocenters fused in one ring structure, were smoothly obtained in high yields (up to 89% yield) with good diastereoselectivity (up to >20:1). Valuable feature of this method was the design of new hybrid architectures for biological screenings through creating molecular diversity and complexity by means of the generation of several bonds and rings in a single operation. In particular, their biological activity against human leukemia cells K562 and normal L929 cells have been evaluated. These results suggested changes of this chromanone group could obviously impact the activity, and a chromanone group located in the polycyclic pyrrolidinyl‐dispirooxindoles is beneficial for the activity. What is more, the results also indicated that chromanone‐fused polycyclic pyrrolidinyl‐dispirooxindoles 3 have selective cytotoxicity against cancer cells K562 compared with normal cells L929. [ABSTRACT FROM AUTHOR]

A new short approach to (--)-lepadins A--C has been developed based on a stereocontrolled Diels--Alder reaction employing a chiral dienophile. With this approach, (--)-lepadin B is synthesized from 5-deoxy-d-ribose in 13 steps with 14.8% overall yield. The cis-decahydroquinoline core containing five stereocenters could be rapidly constructed via stereoselective cycloaddition and subsequent five-step one-pot hydrogenation--cyclization. [ABSTRACT FROM AUTHOR]

A facile and efficient methodology was developed for the synthesis of isoxazole or coumarin-fused 3-quaternary carbon oxindoles and isoxazole-fused pyrrolidinones via DABCO-catalyzed sp 3 C–H activation of 5-methyl-isoxazole or 4-methylcoumarin. Furthermore, the biological activity of the isoxazole or coumarin-fused 3-quaternary carbon oxindoles 3 and 5 has been preliminarily demonstrated by in vitro evaluation against human prostate cancer cells PC-3 and human leukemia cells K562 by the MTT-based assays using the commercially available standard drug Cisplatin as a positive control. These results suggested that most of the compounds 3 and 5 showed considerable cytotoxicities to these two cell lines K562 and PC-3, and a methyl or an ethyl group of acrylates and an oxindole moiety located in the isoxazole-fused 3-quaternary carbon oxindoles 3 are beneficial for the activity. In addition, the activity of all the afforded isoxazole-fused pyrrolidinones 7 were also evaluated against Gram-positive bacteria Staphylococcus aureus (MTCC96) and Gram-negative bacteria Escherichia coli (ATCC25835) using Penicillin as a standard drug for Gram-positive organism or Streptomycin as standard drug for Gram-negative organism. The results demonstrated that most of the compounds 7 had comparable in vitro inhibitory activity against Gram-positive bacteria Staphylococcus aureus (MTCC96) with the positive control Penicillin. The results also indicated that isoxazole-fused pyrrolidinone analogs had significantly better inhibition ability against Gram-positive bacteria Staphylococcus aureus (MTCC96) than against Gram-negative bacteria Escherichia coli (ATCC25835). [ABSTRACT FROM AUTHOR]

In search of environmentally benign insecticides with high activity, low toxicity and low residue, a series of novel anthranilic diamides containing allyl ether were designed and synthesized. All the compounds were characterized by H NMR spectroscopy, HRMS or elemental analysis. The single crystal structure of 18e was determined by X-ray diffraction. The insecticidal activities of the new compounds were evaluated. The results showed that some compounds exhibited excellent insecticidal activities against Lepidoptera pests. Among this series compounds, 18l showed 100 % larvicidal activity against Mythimna separate Walker and Plutella xylostella Linnaeus at the test concentration. [ABSTRACT FROM AUTHOR]

Highlights: [•] Graphene–ZnO hybrid was synthesized by one-step electrochemical deposition. [•] Graphene–ZnO hybrid presents a special structure and wide UV–vis absorption spectra. [•] Graphene–ZnO hybrid exhibits an exceptionally higher photocatalytic activity for the degradation of dye methylene blue. [ABSTRACT FROM AUTHOR]

An Al-substituted tobermorite was prepared by hydrothermal treatment using 4A-zeolite, sodium silicate, and calcium hydroxide. The X-ray diffraction (XRD) patterns and FT-TR spectra confirmed that tobermorite was formed after the hydrothermal process. The removal of phosphorous using the synthesized tobermorite was studied. XRD patterns, FT-TR spectra, and scanning electron microscope (SEM) images showed the formation of hydroxyapatite after p-elimination. It was found that the best solid/liquid ratio is 1.0 g/L and the best pH value is 9. Kinetic models and thermodynamic parameters of p-elimination were discussed, and the p-elimination process was proved to follow pseudo-second-order rate kinetics; it was spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

l -theanine, the most represented non-proteinogenic amino acid in tea plants (Camellia sinensis), is extensively utilized as a food supplement and a pharmaceutical, nutraceutical, and cosmetic ingredient. Tea plants are major sources of l -theanine, however, successfully extracting l -theanine from plants is limited by environmental conditions. Furthermore, the chemical synthesis of l -theanine is inefficient owing to the coproduction of undesirable stereoisomers that affect downstream applications. To overcome these problems, microbial engineering processes based on enzymatic catalysis and fermentation have emerged as sustainable manufacturing approaches for l -theanine biosynthesis. Advantages of these processes include the availability of well-established microbial engineering tools and strategies and high production rates. In this review, we first introduced the natural biosynthetic pathway of l -theanine production and discussed the detailed microbial or enzymatic processes involved in l -theanine production. We then summarized the information from recently published studies on the production of l -theanine using microbial platforms, emphasizing the latest advances and most relevant process parameters in l -theanine biosynthesis. As an alternative approach to the non-environmentally friendly and largely energy-consuming traditional methods, the microbial production of l -theanine is expected to be successfully utilized in various industrial applications. • Recent advances of the l -theanine biosynthesis pathway in nature were introduced. • Several microbial enzymes with l -theanine biocatalysis ability were characterized. • The main three host strains for the production of l -theanine were discussed. • Fermentation plays an important role for improving the production of l -theanine. [ABSTRACT FROM AUTHOR]

Abstract Since pyrithiobac (PTB) is a successful commercial herbicide with very low toxicity against mammals, it is worth exploring its derivatives for an extensive study. Herein, a total of 35 novel compounds were chemically synthesized and single crystal of 6 – 6 was obtained to confirm the molecular structure of this family of compounds. The novel PTB derivatives were fully evaluated against various biological platforms. From the bioassay results, the best AHAS inhibitor 6–22 displayed weaker herbicidal activity but stronger anti -Candida activity than PTB did. For plant pathogenic fungi, 6–26 showed excellent activity at 50 mg/L dosage. Preliminary insecticidal activity and antiviral activity were also observed for some title compounds. Strikingly, 6–5 exhibited a promising inhibitory activity against SARS-CoV Mpro with IC 50 of 4.471 μM and a low cellular cytotoxicity against mammalian 293 T cells. Based on the results of molecular modeling, HOMO-1 was considered to be a factor that affects AHAS inhibition and a possible binding mode of 6 – 5 with SARS-CoV Mpro was predicted. This is the first time that PTB derivatives have been studied as biological agents other than herbicides. The present research hence has suggested that more attentions should be paid to compounds belonging to this family to develop novel agrochemicals or medicines. Graphical abstract Image 1 Highlights • A total of 35 novel pyrithiobac derivatives were chemically synthesized. • Compound 6–22 showed strong inhibition against fungal AHAS and plant AHAS. • Compound 6 – 5 showed potent inhibition against SARS-CoV Mpro. • Crystal structure of 6 – 6 was obtained and elucidated. • Molecular simulations were performed for the target compounds. [ABSTRACT FROM AUTHOR]

Highlights: [•] In situ formation of 2,5-disulfonylterephthalate acid derived from 5-sulfonyl-1,2,4-benzenetricarboxylic acid. [•] 2,5-Disulfonylterephthalate acid ligand. [•] Ni(II) and Mn(II) compounds. [•] Antiferromagnetic couplings between the Ni(II) ions. [•] Antiferromagnetic couplings between the Mn(II) ions. [ABSTRACT FROM AUTHOR]

Two isomorphous compounds [Eu(2,2′-bpdc)(NO3)(e-urea)3]n (1) and [Tb(2,2′-bpdc)(NO3)(e-urea)3]n (2) (2,2′-bpdc2−=2,2′-biphenyldicarboxylate and e-urea=ethyleneurea) have been synthesized using a deep-eutectic solvent of choline chloride/e-urea. The lanthanide ions are linked by the 2,2′-bpdc2− ligands to form one-dimensional helical chains in these compounds. Of special interest is the presence of parallel left- and right-handed single helices with the ratio of 1:1 in both compounds. Detailed photoluminescence studies show that both compounds exhibit typical lanthanide luminescent emissions and the excitation energy has been efficiently transferred to the lanthanide ions from the organic ligands. [ABSTRACT FROM AUTHOR]

A facile and efficient methodology is developed for the synthesis of multifunctional polycyclic spiropyrrolidine oxindoles via a three-component 1,3-dipolar cycloaddition reaction of dienones (III) with azomethine ylides (thermally generated in situ from isatin derivatives and proline or thioproline). [ABSTRACT FROM AUTHOR]

Optimized conditions allow the diastereoselective reaction of 3-aminooxindoles with α,α-dicyanoolefins to give the title compounds in high yields. [ABSTRACT FROM AUTHOR]