查看更多>>摘要：Reported herein is a visible light-induced C-H trifluoromethylation of quinoxalin-2(1H)-ones with CF3SO2Cl as CF3 radical source under photocatalyst-free conditions. The reaction proceeds smoothly through a radical process in the absence of photocatalyst and oxidant in moderate to good yields, thus offering an efficient and green method for the synthesis of 3-trifluoromethyl quinoxalin-2(1H)-ones.(C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Papiliomyces sp. was found in 2020, and its secondary metabolites have never been reported. Papililone A (1), a new tetracyclic diterpenoid with an unprecedented 5/5/5/6 ring system, was isolated from Papiliomyces sp. under the guidance of HPLC-MS/MS investigation. This structure was assigned by detailed spectroscopic analysis, calculated electronic circular dichroism, and computer-assisted structure elucidation. Moreover, 1 exhibited moderate inhibitory activity against lipopolysaccharide induced nitric oxide production in RAW264.7 cells with IC50 value of 30.9 +/- 1.52 mM. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Macrocyclic and cage structures preorganize functional groups around a central cavity providing unique properties in the field of supramolecular chemistry. Their synthesis requires an appropriate design of the building blocks that will form a macrocycle through a macrocyclization reaction or a cage through a cage formation reaction. Besides the importance of the appropriate geometry of the building blocks, it is necessary to design a suitable synthetic route with special attention to the final macrocyclization or cage formation reaction pathway. The kinetic and thermodynamic aspects are crucial factors to consider for a successful reaction that will be analyzed in this digest. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Since amines are present in many organic, biological, and drug molecules, a strategy of synthesizing desired compounds by nucleophilic substitution reactions of these amines is very attractive. By using triazine reagents, we have found that nucleophilic substitution reactions of unbranched alkyl amines via morpholine derivatives are feasible. This method can be performed under milder reaction conditions than those in previously reported methods. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Amino pyranosides are an important component of natural products like vancomycin and erythromycin. The amine moiety mediates interactions with the biological targets of the compounds and it also influences physicochemical properties. Seven-membered ring septanose carbohydrates hold potential as ring-expanded glycomimetics of pyranosides. Methods for the synthesis of septanose carbohydrates are an essential pre-requisite for their broader application in chemical glycobiology and medicinal chemistry. Here we present the first reported synthesis of 3-aminoseptanosides. Starting from D-ribofuranose, the synthesis Key steps in the sequence include addition by allyl Grignard to a furanosyl amine, ozonolysis, and glycosidation to form the seven-membered ring. Importantly, glycosidation with alcohols like propargyl alcohol introduced a reactivity handle onto the aglycon. Propargyl 3-amino septanosides were subjected to alkyne-azide click cycloaddition reactions with representative azides. This exercise illustrated the post-glycosylation diversification of septanosides, linking our interest in ring-expanded glycomimetics and methods for preparing collections of glycosylated small molecules. (c) 2022 Elsevier Ltd. All rights reserved.
An, Pei-PeiCui, Yong-ShengShi, Qiong-YuRen, Yu-Hao...
4页
查看更多>>摘要：Four new pregnanes (1-4), including one 21-norpregnane (4), together with two known pregnanes (5 and 6), were isolated from the twigs and leaves of Strophanthus divaricatus. Their structures were elucidated on the basis of spectroscopic data analysis, ECD data, and X-ray crystallographic study. The cytotoxic activities of these pregnanes against two human cancer cell lines were evaluated. CO 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A mild and efficient method for hydroxymethylation of active methenyl compounds has been described. In this transformation, the widely available solvents DMSO and H2O served as methylene and oxygen sources, respectively. Under promotion of activator and base, the reaction could be used for the construction of a series of alpha-hydroxymethylated carbonyl compounds with all-carbon quaternary carbon center in good to excellent yield. (C) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Three new merosesquiterpenoids, 24-methylsulfinyllancoquinone B (1), pelorol A (2), and epi-langconol A (3), along with eight known related analogues, were isolated from a marine sponge Spongia pertusa Esper. The compounds were completely characterized by NMR spectroscopy and HRESIMS. Compound 1 had a friedo-drimane sesquiterpenoid skeleton bearing a rare 3-(methylsulfinyl)propan-1-amine func-tionality, whereas 2 and 3 were members of the drimane-type sesquiterpenoid derivatives. Compounds 1, 4, 6, 7, and 8 exhibited moderate antifungal activity against three human pathogens, namely, Candida albicans, Trichophyton mentaqrophytes, and Trichophyton rubrum, with MIC50 values ranging from 12.5 to 50 lg/mL. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：Herein we report a synthetic a-amino acid featuring intensely fluorescent coumarin moiety and a strongly self-assembling ureidopyrimidinone (UPy) motif. This two-in-one synthetic amino acid, displaying both fluorescence and self-assembling property, has been synthesized in four easy steps starting from commercially available inexpensive starting materials. Suitably protected amino acid has been incorporated into various peptide sequences, following solution-phase peptide coupling protocols, to demonstrate its synthetic feasibility.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：A novel sulfur-and peroxy-bridged twelve-membered macrolide, cladosporioidin A (1), and a new iodinated dimeric naphtho-c-pyrone, (aS)-6-iodofonsecinone A (2), were obtained from a marine cold-seep isolate (8-1) of Cladosporium cladosporioides. Their structures and relative/absolute configurations were unequivocally established by combination of various spectroscopic techniques, mainly including NMR, MS, and ECD. Compounds 1 and 2 were assayed to feature antimicroalgal and antibacterial activities. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.
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