New Sesquiterpene Lactones from Carpesium Lipskyi

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Synthesis of 2,5-disubstituted tetrahydrofurans from organozinc halides and lactones

2,5-Disubstituted tetrahydrofurans were obtained from lactones and organozinc halides in moderate to high yield in the presence of Lewis acids.

Two New Eremophilane Sesquiterpene Lactones from Ligularia myriocephala Ling

Two new eremophilane sesquiterpene lactones, 1β-angeloyloxy-6β, 10β-dihydroxy-8β- methoxyeremophila-7（ll）en-8α,12-olide and 1β-angeloyloxy-6β,10α-dihydroxy-8α-methoxyeremo- phila-7（ 11）en-8β, 12-olide were isolated from the extract of the whole plant of Ligularia myriocephala Ling. Their structures and stereochemistry were elucidated by various spectroscopic methods including intensive 2D-NMR techniques （COSY, gHMQC, gHMBC and ^1H-^1H NOESY） and HR-ESIMS.

Synthesis of Macrocyclic Lactones Building on Double Calix[4]arenes

The macrocyclic lactones building on calix[4]arenes 3a-b and double calix[4]arenes 4a-b were synthesized by the reaction of p-tert-butylcalix[4]arene (1a) or calix[4]arene (1b) with glycol bis(2-chloroacetate) (2). The conditions to improve the yields of double calix[4]arenes have been discussed.

PREPARATION OF ENANTIOMERICALLY PURE SYN-4,5-DIHYDROXY CARBOXYLIC ACID LACTONES BY MICROBIAL REDUCTION

Enantiomerically pure syn-4,5-dihydroxy carboxylic acid lactones were prepared by microbial reduction of acyl lactones with resting cell of Aspergillus niger.

STUDIES ON CYCLOPENT-2-ENONE: (Ⅳ)PREPARATION OF UNSATURATED δ-LACTONES FROM THE ALDOLS OF CYCLOPRNT-2-ENONE

A new route was developed for diastereoselective preparation of δ-(α-hydroxyalkyl)-αβ-unsaturated δ-lactones. A single diastereoisomer(14) of the lactone was obtained after oxidation and elimination of (12).

THE STUDY OF ENZYMATIC SYNTHESIS OF MACROCYCLIC LACTONES

The effects of the chain length and stereo-factor of substrates and solvents on the lipase catalysed lactonization of ω-hydroxy-ester were studied, And also the catalytic effects of various enzymes were compared.

Sesquiterpene Lactones from Notoscris Porphyrolepis

Two new sesquiterpcne lactones, notoserolides A and B. along with 12 known compounds were isolated from the aerial parts of Notoseris porphyrolepis. By means of spectral methods including MS. NMR (1H NMR. 13C NMR. DEPT. HMQC. HMBC) and X-ray diffraction. as well as chemical reactions. the structures of notoserolides A and B were established as auslricin 8-O-β-D-glucopyranoside and 8-O-senecioylaustricin. respectively.

N-Acylhomoserine Lactones (AHLs), QseB/C Gene Detection, Virulence Factors and Antibiotics Resistance of <i>Aeromonas hydrophila</i>

The aim of this research was to detect the N-acyl homoserine lactones (AHLs) production and QseB/C gene of Aeromonas hydrophila. We analyzed the potentials of these isolates of Aeromonas hydrophila in causing biofilm formation, hemolysis, protease, and lipase. The antibiotic susceptibility of the 15 Aeromonas hydrophila isolates was also investigated. The detection of AHLs was carried out using the Chromobacterium violaceum strain CV026 as biosensors. The isolated strains were tested for the reaction of C. violaceum CV026 by cross-streaking on an agar plate. Production of AHLs was determined by the diffusing via the agar plates and the tinge of the biosensor strains. All isolated strains produced AHLs. A polymerase chain reaction (PCR) showed the isolated strains had qseB and qseC genes. Susceptibility tests of A. hydrophila isolates were administered against 25 different antibiotic disks representing 12 classes of antibiotics. The strains were highly resistant to β-Lactam with 96.7% showing resistibility, whereas 97.7% susceptibility was found towards Aminoglycoside class of the antibiotic used. 60% showed intermediate resistant to Polypeptide. 100% of the strains showed no resistant to Aminoglycoside, Polypeptide, Monobactam, and Carbapenems class of antibiotics. Each of the isolates was found to be associated with at least one virulent factor. Our results clearly demonstrated that there is a presence of QseB/C genes in A. hydrophila and also produces AHLs molecule and virulence factors. The investigated isolates showed the pathogenic potential of Aeromonas hydrophila which makes it a serious threat to public health.

Sesquiterpene Lactones from Elephantopus scaber

A new germacranolide sesquiterpene lactone, isoscabertopin, was isolated from Elephantopus scaber together with the known scabertopin. Their structures were determined by spectroscopic methods.

Synthesis of macrocyclic lactones with methoxysulfonyl side chain

Two representative macrocyclic lactones with methoxysulfonyl side chain（5a and 5b）were synthesized employing Michael addition with acrolein and ring enlargement as the key steps,starting from potassium,α-oxocycloaikylsulfonates（1）in total yields of 45 and 57%,respectively.

Occurrence of <i>N</i>-Acyl Homoserine Lactones in Extracts of Bacterial Strain of <i>Pseudomonas aeruginosa</i>and in Sputum Sample Evaluated by Gas Chromatography–Mass Spectrometry

This study presents a fast, accurate and sensitive technique using gas chromatography-mass spectrometry (GC-MS) for the identification and quantification of N-acyl homoserine lactones (AHLs) in the extracts of bacterial strain of Pseudomonas aeruginosa and sputum sample of a cystic fibrosis patient. This method involves direct separation and determination of AHLs by using GC-MS as simultaneous separation and characterization of AHLs were possible without any prior derivatiza-tion. Electron ionization resulted in a common fragmentation pattern with the most common fragment ion at m/z 143 and other minor peaks at 73, 57 and 43. The limit of detection for N-butanoyl, N-hexanoyl, N-octanoyl, N-decanoyl, N-dodecanoyl and N-tetradecanoyl homoserine lactones was 2.14, 3.59, 2.71, 2.10, 2.45 and 2.34 μg/L, respectively. The presence of AHLs in the culture of P. aeruginosa strain and spu-tum of a cystic fibrosis patient was achieved in selected ion monitoring (SIM) mode by using the prominent fragment at m/z 143.

Synthesis of Z and E-(2',5'-dimethoxyphenyl)-methylene-butyrolactones

A pair of Z and E isomers of cyclization of γ-ketoacid 7, which was prepared in six steps from 2,5-dimethoxyphenyl acetic acid 1, gave a pair of Z(20%) and E (4%) isomers of (2,5-dimethoxyphenyl)-methylene-butyrolactones

Three rare anti-inflammatory sesquiterpene lactones from Magnolia grandiflora

Four new sesquiterpene lactones(SLs)(1–4),along with a biosynthetically related SL(5),have been isolated from the leaves of Magnolia grandiflora.Magrandate A(1)is notable as the first C18 homogemarane type SL,featuring a unique 1,7-dioxaspiro[4.4]nonan-6-one core.Compounds 2 and 3,representing the first instances of chlorine-substituted gemarane-type SL analogs in natural products,were also identified.The structures of these isolates were elucidated through a combination of spectroscopic data analysis,electronic circular dichroism calculations,and X-ray single-crystal diffraction analysis.All isolates demonstrated anti-inflammatory activity in lipopolysaccharide-stimulated RAW264.7 cells.Notably,3–5 showed a significant inhibitory effect on nitric oxide production,with IC50 values ranging from 0.79 to 4.73μmol·L^(−1).Additionally,4 and 5 exhibited moderate cytotoxic activities against three cancer cell lines,with IC50 values between 3.09 and 11.23μmol·L^(−1).

Anti-inflammatory germacrane-type sesquiterpene lactones from Vernonia sylvatica

Nine new germacranolides,sylvaticalides A−H(1-9),and three known analogues(10-12)were isolated from the aeri-al part of Vernonia sylvatica.Their structures were established using comprehensive spectroscopic analysis,including high-resolution electrospray ionization mass spectroscopy(HR-ESI-MS)and 1D and 2D nuclear magnetic resonance(NMR)spectra.Their absolute configurations were determined by X-ray diffraction experiments.The anti-inflammatory activities of all isolated compounds were as-sessed by evaluating their inhibitory effects on the nuclear factor kappa B(NF-κB)pathway,which was activated by lipopolysacchar-ide(LPS)-stimulated human THP1-Dual cells,and the interferon-stimulated gene(ISG)pathway,activated by STING agonist MSA-2 in the same cell model.Compounds 1,2 and 6 showed inhibitory effects on the NF-κB and ISG signaling pathways,with IC_(50)values ranging from 4.12 to 10.57μmol·L^(−1).

Circular Polymers from Ring-Opening Polymerization of Five-Membered(Thio)lactones and Derivatives

The short lifespan of most commercial plastics as disposables and the failure to adequately address the end-of-life issues of synthetic polymers have led to outrageous global plastic pollution and resource depletion.To solve the problem,one of the most effective strategies is to develop circular polymers and thus establish a new circular material economy.Polymers from ring-opening polymerization of five-membered(thio)lactones contribute greatly to this field due to their excellent material performance and recyclability.The emerging topic emphasizes on the monomer design strategies based on five-membered(thio)lactones,and compares the thermal and mechanical properties and depolymerizability of the resulting polymers with different structures.

Difluoroalkylation/Lactonization of Alkenes with BrCF_(2)CO_(2)K via Photoredox Catalysis:Access toα,α-Difluoro-γ-lactones

Due to its unique electronic properties,the difluoromethylene group(CF2)has served as a valuable unity in the design of biologically active molecules.Sinceγ-lactones display a broad range of biological properties,α,α-difluoro-γ-lactones may exhibit unexpected biological activities,and thus their synthesis has received increasing attention.Traditional synthetic methods suffer from tedious multi-step processes,and very few effective methods have been reported recently.Herein,we describe the difunctionalization of alkenes with BrCF_(2)CO_(2)K under photoredox catalysis with the use of a boron-Lewis acid for the access toα,α-difluoro-γ-lactones.In this transformation,the alkene substrates and the used reagents,including BrCF_(2)CO_(2)K and the boron-Lewis acid,PhB(OH)2 or BF3·THF,are cheap and widely available.High efficiency and atom economy may make this protocol attractive.

One-step selective dehydrogenation of cyclic hemiacetal sugars toward to their chiral lactones

Chiral glycosyl lactone is an important class of bioactive compound and pharmaceutical intermediate in nature, especially for chiral lactones with 4 carbon atoms, which are very useful building blocks for synthesis of biologically interesting compounds. Herein, a selective dehydrogenation and solvent matched catalytic system under oxygen-free conditions was developed to try to achieve the one-step direct conversion of cyclic hemiacetal sugars toward their chiral glycosyl lactones. During the process, the inherent structural characteristics of sugar was efficiently utilized, and the transfer of its chiral centers was realized. Under the optimum condition, the corresponding lactones were successfully prepared from C_(4)-C6sugars with cyclic hemiacetal structure in acetonitrile. The reaction mechanism in acetonitrile was explored by the first principle density functional theory calculations and tracking reaction process. It was found that the high lactone yield in acetonitrile was due to the high proportion of α-conformation form among multiple tautomers in it. This selective dehydrogenation process may further extend the possibility of the preparation of chiral synthons from carbohydrates directly.

Bifurcated Rhodaelectro-catalyzed C−H Activation for the Synthesis of Pyrroles and Lactones

While electrocatalyzed alkyne annulations of arenes represent a powerful strategy for the assembly of heteroaromatic motives,electrochemical C(sp2)−H activations of alkenes remain scarce.Herein,a strategy for the rhodaelectro-catalyzed function-alization of enamides is presented for the efficient construction of pyrroles using electricity as a sustainable oxidant.Moreover,the tuning of the solvent system allowed a fascinating switch in chemoselectivity,which is not possible with traditionally used chemical oxidants,giving rise to lactone architectures.The rhoda-electrocatalysis features a broad scope as well as high regio-and chemoselectivities.