The discovery of proper ligands to simultaneously modulate the reactivity and effectively control the stereoselectivity is a central topic in the field of enantioselective C−H activation. Herein, we reported the synthesis of axially chiral biaryls by Pd‐catalyzed atroposelective C−H olefination. A novel chiral spiro phosphoric acid, STRIP, was identified as a superior ligand for this transformation. A broad range of axially chiral quinoline derivatives were synthesized in good yields with excellent enantioselectivities (up to 98 % ee). Density functional theory was used to gain a theoretical understanding of the enantioselectivities in this reaction.

A simple and ubiquitously present group, free amine, is used as a directing group to synthesize axially chiral biaryl compounds by PdII‐catalyzed atroposelective C−H olefination. A broad range of axially chiral biaryl‐2‐amines can be obtained in good yields with high enantioselectivities (up to 97 % ee). Chiral spiro phosphoric acid (SPA) proved to be an efficient ligand and the loading could be reduced to 1 mol % without erosion of enantiocontrol in gram‐scale synthesis. The resulting axially chiral biaryl‐2‐amines also provide a platform for the synthesis of a set of chiral ligands.

Biaryl atropisomers are of great importance in natural products,p harmaceuticals,a nd asymmteric synthesis. The efficient synthesis of these chiral scaffolds with full enantiocontrol and high diversity remains challenging. Reported herein is aP d-catalyzed atroposelective CÀH allylation with tert-leucine as an efficient catalytic chiral transient auxiliary.Awide range of enantioenriched biaryl aldehydes were prepared in synthetically useful yields with excellent enantioselectivity (up to > 99 %e e) through b-O elimination. The reaction could be carried out on agram scale without erosion of the ee value.Avariety of axially chiral carboxylic acids could be obtained with high enantiopurity. The resulting axially chiral biaryl aldehydes and carboxylic acids might be used in asymmetric synthesis as chiral ligands and/or organocatalysts.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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The theoretical analysis and biomimetic conversion confirmed that the oxidative cleavage of the Δ 8,9 double bond of chloranthalactone A (I), an abundant lindenane-type sesquiterpenoid in Chloranthaceae plants, generates 8,9secolindenane (II) with active aldehyde and maleic anhydride fragments that can capture other fragments and produce oligomeric molecules. A careful phytochemical investigation of the leaves of Sarcandra glabra led to the discovery of eight novel 8,9-secolindenane-type sesquiterpenoid oligomers (sarglalactones A−H, compounds 1−8), including three unprecedented trimers (1−3), five unusual dimers (4−8), and five 8,9-secolindenane monomers (sarglalactones I−M, 9−13). Their structures were determined by comprehensive HRMS, NMR, circular dichroism, and X-ray diffraction analyses. Bioassay results showed that these oligomers significantly reversed the multidrug resistance of MCF-7/doxorubicin (DOX) cells and increased the sensitivity of U2 OS cells to DOX by downregulating the HMGB1 expression.

Rocaglates are a series of structurally complex secondary metabolites with considerable cytotoxicity that have been isolated from plants of the Aglaia genus (Meliaceae). A new rocaglate (aglapervirisinRocaglate, a class of structurally complex secondary metabolites from plants of the Aglaia genus (Meliaceae), have attracted great attentions for their considerable cytotoxicity [1][2][3][4][5] . Rocaglates could block cell cycle progression 6-13 from G2 to M and exhibited promising activity in human tumor cell lines and xenograft models. Their cytostatic effects are comparable to those of established anticancer drugs such as vinblastine sulphate, actinomycin D, and hydroxycamptothecine 14,15 . Rocaglates possess cyclopenta [b]benzofuran skeleton, which originates from the [3 + 2] cyclization products of flavonol and diamide (cyclopenta[bc]benzofurans). Silvestrols, featuring an unprecedented dioxanyloxy unit attached to phenyl ring A of the cyclopenta[b]benzofuran skeleton, is a rare subtype of rocaglate, mostly of marked cytotoxicity 8,11,13 . The structure complexity and the potent activities of silvestrols have attracted significant interest in their biosynthesis and total synthesis [16][17][18][19] .In the plant kingdom, silvestrol analogues are characteristically and exclusively present in Aglaia species, and only four silvestrols have been reported 4 as yet. Certain Aglaia species have been used as traditional medicines for treating fever, cough, diarrhoea, and contused wounds 4,5 . In continuation of the discovery of novel and bioactive natural products from plants of the Meliaceae family [20][21][22] , the species A. perviridis, a wild shrub indigenous to Yunnan Province of China 20-22 , was investigated to find cytotoxic rocaglates, particularly silvestrols. As a result, three silvestrol analogues including a new one (aglapervirisin A, 1), eight new biosynthetic precursors of rocaglates (cyclopenta[bc]benzopyrans, 2-9), and three known precursors (12-14) were isolated and purified from the leaves of A. perviridis (Fig. 1). Their structures were mainly elucidated through comprehensive analysis using spectroscopic methods, including IR, UV, MS, HRESIMS, 1D-NMR and 2D-NMR. The absolute configuration of 1 was determined by ECD analysis and chemical conversion, and that of 2 was established by single-crystal X-ray diffraction using Cu Kα radiation. These isolates (except for 6 and 12) were evaluated for their cytotoxicity against four human cancer cell lines: three silvestrol analogues (1, 10 and 11) showed potent activity with IC 50 values between 8.0 and 15.0 nM. Of them, 1 induced cell cycle arrest by reducing the Cdc2 and Cdc25C expression levels in a dose-dependent manner and induced the apoptosis of these cells at concentrations over 160 nM. Herein, we report the separation and structural elucidation of these isolated rocaglate derivatives, as well as the bioassay results.

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Hypermongones A-J (1-10), rare methylated polycyclic polyprenylated acylphloroglucinol derivatives, together with three known simple acylphloroglucinols (11-13) as their plausible biogenetic precursors, were identified from the flowers of Hypericum monogynum. The structures of 1-10 were elucidated by analysis of their 1D and 2D NMR spectroscopic data; the absolute configuration of their polycyclic skeleton was determined by the electronic circular dichroism exciton chirality method and was subsequently confirmed by an X-ray diffraction study of 1. The evaluation of their inhibitory effects on nitric oxide (NO) production in lipopolysaccharide-induced RAW264.7 cells revealed that compound 7 exhibited significant NO inhibition activity, with an IC50 value of 9.5 μM.