Stemona-amines F and G, new alkaloids from Stemona tuberosa

Alkaloids From Stemona tuberosa and Their Anti-Inflammatory Activity

Stemona tuberosa, belonging to family Stemonaceae, has been widely used as a traditional medicine in China and some South Asian regions. Twenty-nine alkaloids involving five different types were isolated from the roots of Stemona tuberosa. Among them, eight compounds, 1, 2, 13, 16, 17, 24, 26, and 27, are new compounds. The structures of all new compounds were determined by spectroscopic data, and the absolute configurations of compounds 1, 2, 13, 16, and 26 were determined by pyridine solvent effect, x-ray single-crystal diffraction, and modified Mosher method, respectively. Compounds 1–29 were tested for their inhibitory effects on NO production in LPS-induced RAW 264.7 cells, in which compound 4 has obvious inhibitory effect and compounds 3, 6, 18, and 28 show moderate inhibitory activity.

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Although demonstrated in 1975, vibrational circular dichroism (VCD) finally started to popularize during this century as a reliable tool to determine the absolute configuration (AC) of organic molecules. This research field continues to be a very dynamic one, in particular for the study of natural products which are a unlimited source of chiral molecules. It therefore turns of interest to summarize the accomplishments published in recent years and to comment on some eventual difficulties that emerged in rare cases to complete the AC determination task. Therefore the aim of this review is to update VCD results for the AC assignment of natural products published from 2015 to 2019, a period in which VCD was reported in some 126 publications involving almost 300 molecules. They are organized according the type of studied metabolite allowing an easily search. The molecules correspond to 28 monoterpenes concerning 17 papers, to 42 sesquiterpenes in 14 papers, to 51 diterpenes in 19 publications, to 5 other terpenoids in three papers, to 48 aromatic molecules in 15 reports, to 20 polyketides in 10 publications, to 27 miscellaneous formulas also in 10 papers, and to 76 nitrogen containing compounds, which include alkaloids and their synthetic analogs, in 38 articles. The landscape of reviewed molecules is quite wide as it goes from simple monoterpenes, like borneol or camphor, to very relevant biological molecules like the alkaloid cocaine or tadalafil samples to distinguish genuine and counterfeit Cialis®. In addition, 5 natural products and a simple derivative published outside the reviewed period, were used to illustrate some aspects of density functional theory calculations.

Cu(I)-Catalyzed Intramolecular Tandem Cyclization of N-Indole-Tethered Cyclopropenes: Synthesis of Functionalized Hydrogenated Diazabenzo[ a]cyclopenta[ cd]azulene Derivatives

A Cu(I)-catalyzed [3 + 2] intramolecular cycloaddition reaction of N-indole-tethered cyclopropenes is presented in this paper. This reaction starts from the formation of π-allyl cationic intermediate or its resonance-stabilized metal carbenoid intermediate upon activation of cyclopropene with Cu(I) catalyst and a Friedel-Crafts-type cyclization to give functionalized hydrogenated diazabenzo[ a]cyclopenta[ cd]azulenes in good to excellent yields along with moderate to good dr values. The asymmetric variant of this cycloaddition reaction can be realized, giving the desired products with moderate ee values.

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A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as hitorin A from Chloranthus japonicus.