Copper-Mediated Oxidative Chloro- and Bromodifluoromethylation of Phenols.

The first oxidative chloro- and bromodifluoromethylation of phenols with (CH3)3SiCF2X and CuX (X = Cl or Br) in the presence of Selectfluor under mild reaction conditions was developed. This protocol provided a practical and efficient method for the synthesis of a diverse range of biologically valuable and synthetically challenging chloro- and bromodifluoromethyl aryl ethers. Preliminary mechanistic studies suggest that this reaction proceeded through a difluorocarbene-involved oxidative coupling process.

N-Trifluoromethoxyphthalimide: A Shelf-Stable Reagent for Nucleophilic Trifluoromethoxylation.

Due to the unique properties of the OCF3 group, trifluoromethyl ether compounds play an important role in pharmaceuticals and agrochemicals. Recently, considerable attention has been focused on the development of practical and convenient reagents for the direct incorporation of the OCF3 group into organic compounds. Herein, we reported a new trifluoromethoxylating reagent N-trifluoromethoxyphthalimide (Phth-OCF3). The reagent was a stable solid and released an OCF3 anion under mild reaction conditions. We demonstrated the application of Phth-OCF3 for the nucleophilic trifluoromethoxylation of various alkyl electrophiles.

The state of social science research on COVID-19.

Research on COVID-19 has proliferated rapidly since the outbreak of the pandemic at the end of 2019. Many articles have aimed to provide insight into this fast-growing theme. The social sciences have also put effort into research on problems related to COVID-19, with numerous documents having been published. Some studies have evaluated the growth of scientific literature on COVID-19 based on scientometric analysis, but most of these analyses focused on medical research while ignoring social science research on COVID-19. This is the first scientometric study of the performance of social science research on COVID-19. It provides insight into the landscape, the research fields, and international collaboration in this domain. Data obtained from SSCI on the Web of Science platform was analyzed using VOSviewer. The overall performance of the documents was described, and then keyword co-occurrence and co-authorship networks were visualized. The six main research fields with highly active topics were confirmed by analysis and visualization. Mental health and psychology were clearly shown to be the focus of most social science research related to COVID-19. The USA made the most contributions, with the most extensive collaborations globally, with Harvard University as the leading institution. Collaborations throughout the world were strongly related to geographical location. Considering the social impact of the COVID-19 pandemic, this scientometric study is significant for identifying the growth of literature in the social sciences and can help researchers within this field gain quantitative insights into the development of research on COVID-19. The results are useful for finding potential collaborators and for identifying the frontier and gaps in social science research on COVID-19 to shape future studies.

[Fingerprints of Curcuma wenyujin by RP-HPLC].

OBJECTIVE: To establish a mutual mode fingerprint of Curcuma wenyujin for quality control of C. wenyujin. METHODS: Waters Symmetry C18 column was used; the mobile phase was methanol-water in a linear gradient elution with the flow rate of 1.0 mL/ min, the temperature of column was 30 degrees C; the detection wavelength was set at 215 nm. 10 batches of C. wenyujin from different places and different time were determined, 3 batches of C. phaeocaulis and 3 batches of C. kwangsiensis were determined in the same chromatographic conditions. RESULTS: 11 mutual peaks in the fingerprint of the 10 groups of C. wenyujin, and the S peak among them represented germacrone. CONCLUSION: Curcuma wenyujin's fingerprints have strong feature and specificity, which can be combined with assaying in the quality control of C. wenyujin.

Diterpenes with potential treatment of vitiligo from the aerials parts of Euphorbia antiquorum L.

Six new diterpenes Euphonoids A-F including one ingenol (1), three lathyrane (2-5), one ent-abietane (6) and fifteen known derivatives (7-21) were isolated from the aerial parts of Euphorbia antiquorum L. Their structures were elucidated by physical data analysis. Compounds 1, 12, and 16 improve the melanogenesis in B16 cells in vitro.

12ß-Acetyloxyperforatin, a New Limonoid from Harrisonia Perforata.

A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11ß-HSD1 enzyme.

Abietane Diterpernoids from the Roots of Euphorbia ebracteolata.

A new ent-abietane diterpernoid, named ebracteolata D (1), along with 11 known analogues, was isolated from the roots of Euphorbia ebracteolata Hayata. The structure of 1 was elucidated on the basis of spectroscopic analysis and molecular modeling. Cytotoxicity of compounds 1-12 was evaluated as well as the effect on the NF-κB pathway. Among them, compound 12, jolkinolide B, displayed broad inhibitory effects against proliferation of tumor cell lines. Mechanistic studies indicated that the compound 12 can inhibit TNF-α induced NF-κB activation, thereby inducing tumor cell apoptosis.

(±)-Perforison A, A Pair of New Chromone Enantiomers from Harrisonia perforata.

(+)-Perforison A and (-)-perforison A, a new pair of chromone enantiomers, along with four known compounds, were isolated from the leaves and stems of Harrisonia perforata. Their structures and absolute configurations were determined on the basis of extensive analysis of spectroscopic data and electronic circular dichroism (ECD) calculations. The cytotoxic activities in vitro of these compounds were evaluated, but none showed significant activity.

Two novel diterpenoid heterodimers, Bisebracteolasins A and B, from Euphorbia ebracteolata Hayata, and the cancer chemotherapeutic potential of Bisebracteolasin A.

Rare ent-abietane-rosane diterpenoid heterodimers, Bisebracteolasins A and B (1 and 2, respectively), were isolated from the roots of Euphorbia ebracteolata Hayata. Their structures and absolute configurations were elucidated from spectroscopic data and X-ray diffraction analysis. Compounds 1 and 2 exhibited moderate cytotoxic effects against five cancer cell lines. Compound 1 showed more effective antiproliferative activities against human tumour cells, HL-60 and SMMC-7721, with IC50 values of 2.61 and 4.08 µM, respectively, than 2. Both compounds 1 and 2 inhibit the colorectal cancer stem cell line P6C with IC50 values of 16.48 and 34.76 µM, respectively. Moreover, preliminary biological tests showed compound 1 exhibited inhibitory activity towards tumoursphere formation and migration of the P6C cell line. Overall, we identified two novel diterpenoid heterodimers, and Bisebracteolasin A exhibits therapeutic potential in impeding tumour growth and metastatic ability of cancer stem cells.