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1.
Six novel neomacrophorin and four novel premacrophorin congeners were isolated from the fungus Trichoderma sp. 1212-03. Their planar structures and relative configurations were determined by conventional NMR and mass spectrometry techniques. The electronic circular dichroism (ECD) spectral comparisons with known neomacrophorins were effective for elucidating the structures of congeners carrying 2,3-epoxybenzoquinone (1, 2) and 2,3-epoxybenzosemiquinol substructures (3, 4, 5, 7, 8, and 9). The configuration of the 6-hydroxy-2-cyclohexene-1,4-dione moiety in 5′-deoxyneomacrophorin IV (6) was elucidated by NMR spectral comparison with those of known purpurogemutantidin (16) and mancrophorin F (17). This also resulted in the configurational revision of 16. The relative configuration of the 5,6-epoxy-2-cyclohexen-1,4-diol in premacrophorintriol-II (10) was determined by 13C chemical shift analysis using density functional theory calculations at the ωB97X-D/6-31G* level of theory. Compounds 1 and 6 exhibited potent cytotoxicity against human Caucasian colon adenocarcinoma cell line COLO 201. 相似文献
2.
Guozhu Su Shungang Jiao Ruifei Zhang Li Li Suyile Chen Pengfei Tu Xingyun Chai 《Tetrahedron letters》2018,59(14):1356-1359
A new 7, 9′-epoxylignan, alashinol H (1), which features a rare six-membered cyclic hemiacetal, was isolated from the stem barks of Syringa pinnatifolia. The structure was elucidated based on spectroscopic data including HRESIMS and NMR. Its absolute configuration was resolved by GIAO NMR shifts and ECD calculations. A putative biosynthetic pathway of this compound is proposed. Alashinol H showed a moderate inhibitory effect against NO production in BV-2 murine microglia cells. 相似文献
3.
Jiang-Bo He Yan-Nan Ji Dong-Bao Hu Shen Zhang Hui Yan Xin-Chun Liu Huai-Rong Luo Hua-Jie Zhu 《Tetrahedron letters》2014
Penicilliumine (1), a new structure was isolated from the fermentation Penicillium commune 366606, a marine-derived fungus isolated from the sea water collected at Qingdao, China. HPLC chiral separation of 1 afforded two enantiomers (−)-penicilliumine and (+)-penicilliumine, respectively. The structure of 1 was established by comprehensive spectroscopic data, and single-crystal X-ray diffraction. The absolute configuration of enantiomers was determined by quantum mechanical computation of electronic circular dichroism (ECD). 相似文献
4.
5.
Xin Fang Qiang Zhang Shu-Zhen Mu Yong-Bin Lu Ying-Tong Di Xiao-Jiang Hao 《Tetrahedron》2009,65(36):7408-572
Six new rings B,D-seco-type limonoids, cipadonoids B-G (1-6) were isolated from leaves of Cipadessa cinerascens. Their structure was elucidated by extensive spectroscopic methods, and that of 1 was confirmed by single-crystal X-ray diffraction. The absolute configuration of compounds (2-6), a class of cipadesin-type limonoids, was determined by CD exciton chirality method and chemical means, representing the first report of assignment of absolute configuration of such type compounds; a biosynthetic pathway of 2-6 was proposed and confirmed by chemical correlation and computational result. Compound 1 showed weak in vitro activity at the insect nicotinic acetylcholine receptor (nAChR). 相似文献
6.
Hui Min Wu Li Ping Lin Qin Lan Xu Wen Bo Han Song Zhang Ze Wen Liu Ya Ning Mei Zhu Jun Yao Ren Xiang Tan 《Tetrahedron letters》2017,58(7):663-665
Nodupetide (1), a new cyclodepsipeptide unique in its incorporation of a 3-hydroxy-4-methylhexanoic acid (HMHA) derived motif, was discovered from Nodulisporium sp. IFB-A163, a fungus residing in the insect (Riptortus pedestris) gut. The nodupetide structure was elucidated by its MS/MS and 2D NMR spectra, and its absolute configuration by the X-ray crystallography and modified Marfey’s method. Nodupetide is insecticidal against rice brown planthopper (Nilaparvata lugens) with an LD50 value of 70 ng/larva, and inhibitory towards the drug-resistant human pathogenic bacterium Pseudomonas aeruginosa with its MIC value (5.0 μM) comparable to that (3.2 μM) of ciprofloxacin, a prescribed antibacterial agent co-assayed equally. 相似文献
7.
A simple and efficient synthesis of optically active insect pheromones, such as (R)- and (S)-3-octanol, (R)-2-dodecanol, (R)-2-methyl-4-heptanol and (R)-2-methyl-4-octanol starting from non-racemic β-hydroxy sulfides has been established. 相似文献
8.
Lin-Fu Liang Tibor Kurtán Attila Mándi Li-Gong Yao Jia Li Le-Fu Lan Yue-Wei Guo 《Tetrahedron》2018,74(15):1933-1941
A series of highly oxidative new cembranoids with diverse structural features such as a dienoate moiety (sarcophytonolides S – U, 1–3) or an α,β-unsaturated ε-lactone (sartrolides H – J, 4–6) were obtained from Hainan soft coral Sarcophyton trocheliophorum, along with known related analogues 7–13. It is an extremely challenging work to determine the absolute configurations of these metabolites. For compounds 1, 3 and 4, solution TDDFT calculation of ECD and specific rotation were applied in combination with conformational analysis and NMR data to determine their relative and absolute configurations, leading to the revision of relative configuration of 14. The absolute configurations of compounds 8–10 were determined by the solid-state TDDFT-ECD approach, and that of 8 was further confirmed by single-crystal X-ray diffraction experiment with Cu Kα radiation. In the bioassays, compound 8 exhibited not only moderate protein tyrosine phosphatase 1B (PTP1B) inhibitory activity (IC50?=?15.4?μM) but also moderate antibacterial activity against Staphylococcus aureus Newman strain (MIC50?=?250?μM). 相似文献
9.
Cheng-Qi Fan 《Tetrahedron》2007,63(29):6741-6747
Tabularisins A-D (1-4), a new class of phragmalins incorporating a cyclopropanyl ring, were isolated from Chukrasia tabularis. Compounds 1 and 2 are also the first examples of phragmalins with an 8,9,11-ortho ester. The structures of 1 and 3 were confirmed by single crystal X-ray studies. The absolute configuration of 2 was determined by CD exciton chirality method on its benzoate (2a), and those of 1, 3, and 4 were proposed by correlating with 2 chemically and biogenetically. 相似文献
10.
Maragenins I, II and III, new pentacyclic triterpenes from Marah macrocapus (Greene) Greene, are shown to be respectively Δ12-, Δ12,17- and Δ17-3β-hydroxy-16-oxo-28-norloeananes on the basis of chemical and spectroscopic evidence. The structural proposal for maragenin I is confirmed by synthesis from echinocystic acid. 相似文献
11.
A novel metabolite, mycoediketopiperazine, was isolated from a fungi culture (M-204036). Its structure and absolute stereochemistry was established by spectroscopic studies, including single-crystal X-ray diffraction analysis. 相似文献
12.
Toshikazu KomodaYasumasa Sugiyama Naoki AbeMisako Imachi Hiroshi Hirota Akira Hirota 《Tetrahedron letters》2003,44(8):1659-1661
Tetrapetalone A (I), C26H33O7N, is a novel lipoxygenase inhibitor isolated from a culture filtrate of Streptomyces sp. USF-4727 strain. Its chemical structure was determined by its spectroscopic evidence and methylation with diazomethane. The stereochemistry was investigated by the coupling constant in 1H NMR, NOESY data and modified Mosher's method. I possessed a tetracyclic skeleton and a β-rhodinosyl moiety, and this is the first report of a compound with such a tetracyclic skeleton. 相似文献
13.
Chengsen TianXiaozhen Jiao Xiaoyu LiuRenze Li Liang DongXiaojin Liu Zhigang ZhangJun Xu Minjuan Xu Ping Xie 《Tetrahedron letters》2012,53(36):4892-4895
The first total synthesis of benzonaphthyridine alkaloid (1), a unique diazaphenathrene alkaloid isolated from mangrove-derived Streptomyces albogriseolus, was accomplished. The core structure was unequivocally constructed via several key transformations, such as Knoevenagel condensation, Curtius rearrangement, and cyclic carbamate formation-reduction sequence. The chiral unsaturated ketone acid moiety was synthesized from N-tert-butoxycarbonyl-l-glutamic acid gamma-tert-butyl ester (15). The absolute configuration was determined. 相似文献
14.
Daniel Jiménez-Teja 《Tetrahedron》2009,65(17):3392-2475
(+)-cis-4-Hydroxy-6-deoxyscytalone, a natural product bio-synthesized by Colletotrichum sp., has been prepared and its absolute configuration confirmed as 3R,4S, the key step being a kinetic racemic resolution of a cis-diol easily obtained from commercial 1,2,3,4-tetrahydronaphthalen-1,5-diol. Four lipases and different reaction conditions were tested in order to obtain the best yield and enantiomeric excess. Confirmation of absolute configuration was made by NMR using a single-derivatization low-temperature procedure and MPA as the auxiliary reagent. 相似文献
15.
Lyngbyacyclamides A (1) and B (2), novel cyclic peptides, were isolated from marine cyanobacteria Lyngbya sp. collected in Okinawa, Japan. Their structures were determined by spectroscopic analyses and degradation studies. They moderately inhibited the growth of B16 mouse melanoma cells. 相似文献
16.
Takaaki Kubota Kazutaka Shimbo Michiko Nakano Jun’ichi Kobayashi 《Tetrahedron letters》2006,47(26):4369-4371
Amphezonol A (1), a novel polyhydroxyl linear carbon-chain metabolite, has been isolated from the cultured marine dinoflagellate Amphidinium sp., which was isolated from an Okinawan marine acoel flatworm Amphiscolops sp. The structure of 1 was elucidated by detailed analyses of 2D NMR spectra. Amphezonol A (1) possesses one tetrahydrofuran ring, two tetrahydropyran rings, and twenty-one hydroxyl groups on C60-linear aliphatic chain with one exo-methylene and one methyl branch. Amphezonol A (1) exhibited a modest inhibitory activity against DNA polymerase α. 相似文献
17.
A novel cytotoxic bis-3-alkylpyridine alkaloid with an azoxy moiety, pyrinadine A (1), has been isolated from an Okinawan marine sponge Cribrochalina sp. (SS-1115), and the structure was elucidated by spectroscopic data and chemical means. 相似文献
18.
Two novel sesquiterpenoids, sinularianins A and B (1 and 2), have been isolated from the Formosan coral Sinularia sp. The skeleton of sinularianins A (1), namely sinulariolane, was found to be unprecedented. Sinularianin B (2), with a novel spiro-butenolide moiety, possesses a valerenane skeleton, which had been reported mostly from the plant. The structures of both metabolites were established by extensive analysis of spectroscopic data. 相似文献
19.
Toshiaki Teruya 《Tetrahedron letters》2005,46(23):4001-4003
Novel 2-alkylpyridine alkaloids, phormidinines A (1) and B (2), were isolated from cyanobacterium Phormidium sp. Their structures were determined by spectroscopic analysis. The absolute stereochemistry of 1 was established by the modified Mosher’s method. 相似文献
20.
Hiroki Shimogawa 《Tetrahedron letters》2006,47(9):1409-1411
The trifluoroacetate salt of cinachyramine (1) was isolated from the Okinawan sponge Cinachyrella sp. This structure was determined by the spectroscopic analysis and the degradation under acidic conditions. Cinachyramine (1) is a novel alkaloid with an unprecedented cage system possessing a hydrazone and two aminals. 相似文献