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1.
The formation of the new optically active C3‐symmetrical receptors (S,S,S)‐ 2 – 4 (Fig. 1), incorporating 1,3,5‐triphenylbenzene and 1,3,5‐tris(phenylethynyl)benzene platforms as ‘floors' and ‘ceilings', is described. The tris(phenylethynyl)benzene derivatives 9 and (S,S,S)‐ 10 (Scheme 1) for the three‐fold peptide coupling to yield the macrocyclic skeletons (Scheme 2) were prepared starting from 1,3,5‐triethynylbenzene by the Sonogashira cross‐coupling reaction. The optical rotations of the three macrocycles (S,S,S)‐ 2 – 4 , two of which ((S,S,S)‐ 2 and (S,S,S)‐ 3 ) are constitutional isomers, differ significantly, which is explained by differential twists induced into the macrocyclic skeletons by the leucine spacer in these bridges. 1 : 1 Host–guest complexes of (S,S,S)‐ 2 – 4 with octyl glucosides (Fig. 3) in CDCl3 are of modest stability (Ka≤270 M ?1 at 300 K). In these complexes, the monosaccharides are most probably nesting on one of the H‐bonding faces of the receptor rather than being accommodated in the cavity. 相似文献
2.
Montecrinanes A–C: Triterpenes with an Unprecedented Rearranged Tetracyclic Skeleton from Celastrus vulcanicola. Insights into Triterpenoid Biosynthesis Based on DFT Calculations 下载免费PDF全文
Dr. Martín Purino Dr. Alejandro E. Ardiles Dr. Oliver Callies Dr. Ignacio A. Jiménez Prof. Isabel L. Bazzocchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7582-7591
Three new triterpenoids with an unprecedented 6/6/6/6‐fused tetracyclic carbon skeleton, montecrinanes A–C ( 1 – 3 ), were isolated from the root bark of Celastrus vulcanicola, along with known D:B‐friedobaccharanes ( 4 – 6 ), and lupane‐type triterpenes ( 7 – 12 ). The stereostructures of the new metabolites were elucidated based on spectroscopic (1D and 2D NMR) and spectrometric (HR‐EIMS and HR‐ESIMS) techniques. Their absolute configurations were determined by both NMR spectroscopy, with (R)‐(?)‐α‐methoxyphenylacetic acid as a chiral derivatizing agent, and biogenetic considerations. Biogenetic pathways for montecrinane and D:B‐friedobaccharane skeletons were proposed and studied by DFT methods. The theoretical results support the energetic feasibility of the putative biogenetic pathways, in which the 1,2‐methyl shift from the secondary baccharenyl cation represents a novel and key reaction step for a new montecrinane skeleton. 相似文献
3.
Wei‐Jan Huang OmV. Singh Chung‐Hsiung Chen Shoei‐Sheng Lee 《Helvetica chimica acta》2004,87(1):167-174
Condensation of 3,4‐dimethoxybenzeneethanamine ( 3d ) and various benzeneacetic acids, i.e., 4a – e , via a practical and efficient one‐pot Bischler–Napieralski reaction, followed by NaBH4 reduction, produced a series of 1‐benzyl‐1,2,3,4‐tetrahydroisoquinolines, i.e., 5a – e , in satisfactory yields (Scheme 3). Oxidative coupling of the N‐acyl and N‐methyl derivatives 6a – e of the latter with hypervalent iodine ([IPh(CF3COO)2]) yielded products with two different skeletons (Scheme 4). The major products from N‐acyl derivatives 6a – c were (±)‐N‐acylneospirodienones 2a – c , while the minor was the 3,4‐dihydroisoquinoline 7 . (±)‐Glaucine ( 1 ), however, was the major product starting from N‐methyl derivative 6e . Possible reaction mechanisms for the formation of these two types of skeleton are proposed (Scheme 5). 相似文献
4.
Fei He Jian‐Xin Pu Sheng‐Xiong Huang Wei‐Lie Xiao Li‐Bin Yang Xiao‐Nian Li Yong Zhao Jian Ding Cheng‐Hui Xu Han‐Dong Sun 《Helvetica chimica acta》2008,91(11):2139-2147
From the dried roots of Euphorbia nematocypha, eight new diterpenoids, with ent‐atisane (i.e., 1 – 5 ) and isopimarane (i.e., 6 – 8 ) type skeletons, together with five known compounds, were isolated. The structures of these new compounds were elucidated by spectroscopic data. Compounds 1 – 8 were evaluated for their cytotoxicity against a small panel of human cancer cell lines. 相似文献
5.
Pestalofones I – K ( 1 – 3 ), three new dimeric meroterpenoids with 2‐(7‐benzoyl‐2,3‐dihydrobenzofuran‐2‐yl)‐1‐phenylethan‐1‐one (in 1 ) and 2‐(7‐benzoyl‐2,3‐dihydrobenzofuran‐2‐yl)‐1‐(3,8‐dioxatricyclo[5.1.0.02,4]oct‐4‐yl)ethan‐1‐one (in 2 and 3 ) skeletons, were isolated from the solid cultures of the plant endophytic fungus Pestalotiopsis fici. The structures of 1 – 3 were elucidated by NMR experiments. Compound 1 was found to be present as a racemic mixture. The absolute configurations of 2 and 3 were deduced by analogy to the previously isolated metabolites pestalofones G and H ( 4 and 5 ) from the same fungus. Biogenetically, compounds 1 – 3 are derived from the same precursors (co‐isolated compounds 9 and 10 ) as the previously isolated compounds 4 – 8 . Compounds 2 and 3 showed weak cytotoxic activities against four human tumor cell lines T24, HeLa, A549, and MCF‐7. 相似文献
6.
Five new alkaloids, gelseganines A–D ( 1 – 4 ) and humantenine N4‐oxide ( 5 ), were isolated from the stems and leaves of Gelsemium elegans. Compounds 1 – 4 represent a rare class of monoterpenoid indole alkaloids that bear an N4‐iridoid unit. The structures of 1 – 5 were determined by spectroscopic analysis, single‐crystal X‐ray diffraction, and chemical correlation, and their absolute configurations were elucidated by CD analysis. A plausible biogenetic pathway for alkaloids 1 – 5 was also postulated. 相似文献
7.
Jun‐Feng Wang Cun‐Li Zhang Qing Lu Ya‐Fang Yu Hui‐Min Zhong Chun‐Lin Long Yong‐Xian Cheng 《Helvetica chimica acta》2009,92(8):1594-1599
Three new cyclic diarylheptanoids myricananins F–H ( 1 – 3 , resp.), along with five known ones, 4 – 8 , were isolated from the roots of Myrica nana. Compound 3 has been obtained by Nagai et al. by reduction of porson with NaBH4. In this work, compound 3 was isolated from natural origin for the first time. The structures of 1 – 8 were elucidated using spectroscopic methods. 相似文献
8.
Smaranda Cota Dipl.‐Chem. Matthias Beyer Dipl.‐Chem. Rüdiger Bertermann Dr. Christian Burschka Dr. Kathrin Götz Dr. Martin Kaupp Prof. Dr. Reinhold Tacke Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(22):6582-6589
The neutral hexacoordinate silicon(IV) complex 6 (SiO2N4 skeleton) and the neutral pentacoordinate silicon(IV) complexes 7 – 11 (SiO2N2C skeletons) were synthesized from Si(NCO)4 and RSi(NCO)3 (R=Me, Ph), respectively. The compounds were structurally characterized by solid‐state NMR spectroscopy ( 6 – 11 ), solution NMR spectroscopy ( 6 and 10 ), and single‐crystal X‐ray diffraction ( 8 and 11 were studied as the solvates 8? CH3CN and 11? C5H12 ? 0.5 CH3CN, respectively). The silicon(IV) complexes 6 (octahedral Si‐coordination polyhedron) and 7 – 11 (trigonal‐bipyramidal Si‐coordination polyhedra) each contain two bidentate ligands derived from an α‐amino acid: (S)‐alanine, (S)‐phenylalanine, or (S)‐tert‐leucine. The deprotonated amino acids act as monoanionic ( 6 ) or as mono‐ and dianionic ligands ( 7 – 11 ). The experimental investigations were complemented by computational studies of the stereoisomers of 6 and 7 . 相似文献
9.
Yen‐Ju Tseng Atallah F. Ahmed Chi‐Hsin Hsu Jui‐Hsin Su Chang‐Feng Dai Jyh‐Horng Sheu 《中国化学会会志》2007,54(4):1041-1044
Two new C‐4 norcembranoids sinulochmodins D ( 1 ) and E ( 2 ), along with three known norditerpenoids ( 3–5 ), have been isolated from the organic extract of a Taiwanese soft coral Sinularia lochmodes (Kolonko). The structures of 1 and 2 were determined on the basis of extensive spectroscopic analyses and by comparison of their spectral data with those of related metabolites. 相似文献
10.
Mengting Liu Weiguang Sun Ling Shen Yan He Junjun Liu Jianping Wang Zhengxi Hu Yonghui Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12219-12223
Bipolarolides A–G ( 1 – 7 ), seven novel ophiobolin‐derived sesterterpenes with three new types of skeletons, were characterized from fungus Bipolaris sp. TJ403‐B1. Their structures were determined via spectroscopic analyses, X‐ray crystallography, and quantum chemical 13C NMR and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 were uniquely defined by a multicyclic caged oxapentacyclo[9.3.0.01,6.05,9.18,12]pentadecane‐bridged system. Compounds 3 and 4 featured an unprecedented 5‐5‐5‐5‐fused core skeleton, while 3 also contained an unexpected C‐3–C‐14 oxygen bridge to construct the caged architecture. Compounds 5 – 7 form a new class of highly modified pentacyclic oxaspiro[4.4]nonane‐containing sesterterpene‐alkaloid hybrids. Their biosynthetic pathways and potential HMG‐CoA reductase inhibitory and antimicrobial activities are also discussed. 相似文献
11.
The seven new triterpenoid saponins 1 – 7 were isolated from the roots of Gypsophila paniculata L. Their structures were established by 1D ‐ and 2D‐NMR techniques, HR‐MS, and acid hydrolysis. The isolated compounds include 3,28‐O‐bidesmosides with or without a 4‐methoxycinnamoyl group (see 1 vs. 2 and 3 ), and 3‐O‐monoglucosides 4 – 7 . All isolated saponins 1 – 7 and their aglycones were evaluated for their α‐glucosidase inhibition activity. Compound 1 showed inhibitory activity against yeast α‐glucosidase with an IC50 value of 100.9±3.3 μM , whereas compounds 2 – 7 were inactive. 相似文献
12.
Kalina Kostova Vladimir Dimitrov Svetlana Simova Manfred Hesse 《Helvetica chimica acta》1999,82(9):1385-1399
The allylic and homoallylic alcohols 1 – 8 , prepared from (+)-camphor and (−)-fenchone, were ozonized in Et2O at −78° and treated with Et3N or LiAlH4 to give the chiral hydroxy carbonyl compounds 9 – 16 and the diols 17 – 24 , respectively (Scheme 1). In the case of the diols 19 and 24 , the formation of new chiral centers proceeded with high diastereoselectivity. These diols were prepared highly diastereoselectively also by LiAlH4 reduction of the hydroxy carbonyl compounds 11 and 16a , respectively (Scheme 2). The absolute configuration of the new chiral centers in 19 and 24 was determined by X-ray and NMR methods. The ozonization of compounds 2 , 3 , 7 , and 8 provided the relatively stable hydroxy-substituted 1,2,4-trioxolane derivatives (ozonides) 37 – 40 (Scheme 5) which were characterized by 1H- and 13C-NMR spectra, ESI-MS, and natural-abundance 17O-NMR spectra. 相似文献
13.
Guang‐Yu Yang Wei‐Lie Xiao Ying Chang Rui‐Rui Wang Jian‐Xin Pu Xue‐Mei Gao Chun Lei Yang Lu Yong‐Tang Zheng Han‐Dong Sun 《Helvetica chimica acta》2008,91(10):1871-1878
Three new highly oxygenated nortriterpenoids, wilsonianadilactones A–C ( 1 – 3 ), together with twelve known ones, i.e., 4 – 15 , were isolated from the leaves and stems of Schisandra wilsoniana. Their structures were established by means of extensive analysis of spectroscopic data, and compound 1 was further confirmed by X‐ray crystallographic diffraction. Compounds 1 – 3 showed weak anti‐HIV‐1 activity with EC50 values of 23.5, 55.5, and 66.4 μg/ml, respectively. 相似文献
14.
Feng‐Xia Ren Feng‐Zhi Ren Yu Yang Neng‐Jiang Yu Yang Zhang Yi‐Min Zhao 《Helvetica chimica acta》2014,97(7):1014-1019
Three new tigliane‐type diterpene esters, 1 – 3 with unusual 7‐oxo‐5‐ene or 7‐hydroxy‐5‐ene moieties in their skeletons, were isolated from the leaves of Croton tiglium. Their structures were unambiguously elucidated on the basis of spectroscopic data. 相似文献
15.
Ya‐Qi Wang Li Bao Xiao‐Li Yang Huan‐Qin Dai Hui Guo Xin‐Sheng Yao Li‐Xin Zhang Hong‐Wei Liu 《Helvetica chimica acta》2012,95(2):261-267
Flamvelutpenoids A–D ( 1 – 4 ), four new cuparene‐type sesquiterpenes, were isolated from the solid culture of Flammulina velutipes. Their structures were elucidated by NMR experiments. The absolute configurations of 1 and 2 were assigned via the circular dichroism data of the [Rh2(OCOCF3)4] complex, whereas that of C(3) of 3 was determined by applying the octant rule for the α,β‐unsaturated ketone moiety. Compounds 1 – 4 showed weak antibacterial activity against Escherichia coli, Bacillus subtilis, and methicillin‐resistant Staphylococcus aureus with MIC values larger than 100 μM . 相似文献
16.
Wei‐Lie Xiao Ying‐Li Wu Shan‐Zhai Shang Fei He Xiao Luo Guang‐Yu Yang Jian‐Xin Pu Guo‐Qiang Chen Han‐Dong Sun 《Helvetica chimica acta》2010,93(10):1975-1982
Four new highly oxygenated nortriterpenoids, lancifodilactones O–R ( 1 – 4 ), together with six known ones, i.e., 5 – 10 , were isolated from the leaves and stems of Schisandra lancifolia. Their structures were elucidated by spectroscopic analyses, including 1D‐ and 2D‐NMR experiments and mass spectrometry. Compounds 1 – 3 were evaluated for their cytotoxicity against NB4, A549, SHSY5Y, PC‐3, and MCF‐7 cell lines. No compounds exhibited significant cytotoxicity, the IC50 values being above 50 μM . 相似文献
17.
Ritu Sharma Pushkal Samadhiya S. D. Srivastava S. K. Srivastava 《Helvetica chimica acta》2012,95(3):514-521
The synthesis of a new series of 4‐aryl‐3‐chloro‐2‐oxo‐N‐[3‐(10H‐phenothiazin‐10‐yl)propyl]azetidine‐1‐carboxamides, 4a – 4m , is described. Phenothiazine on reaction with Cl(CH2)3Br at room temperature gave 10‐(3‐chloropropyl)‐10H‐phenothiazine ( 1 ), and the latter reacted with urea to yield 1‐[3‐(10H‐phenothiazin‐10‐yl)propyl]urea ( 2 ). Further reaction of 2 with several substituted aromatic aldehydes led to N‐(arylmethylidene)‐N′‐[3‐(phenothiazin‐10‐yl)propyl]ureas 3a – 3m , which, on treatment with ClCH2COCl in the presence of Et3N, furnished the desired racemic trans‐2‐oxoazetidin‐1‐carboxamide derivatives 4a – 4m . The structures of all new compounds were confirmed by IR, and 1H‐ and 13C‐NMR spectroscopy, FAB mass spectrometry, and chemical methods. 相似文献
18.
Gyuzel Yu. Mitronova Dr. Vladimir N. Belov Dr. Mariano L. Bossi Dr. Christian A. Wurm Dr. Lars Meyer Dr. Rebecca Medda Dr. Gael Moneron Dr. Stefan Bretschneider Dr. Christian Eggeling Dr. Stefan Jakobs Dr. Stefan W. Hell Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4477-4488
New photostable rhodamine dyes represented by the compounds 1 a – r and 3 – 5 are proposed as efficient fluorescent markers with unique combination of structural features. Unlike rhodamines with monoalkylated nitrogen atoms, N′,N‐bis(2,2,2‐trifluoroethyl) derivatives 1 e , 1 i , 1 j , 3 ‐H and 5 were found to undergo sulfonation of the xanthene fragment at the positions 4′ and 5′. Two fluorine atoms were introduced into the positions 2′ and 7′ of the 3′,6′‐diaminoxanthene fragment in compounds 1 a – d , 1 i – l and 1 m – r . The new rhodamine dyes may be excited with λ=488 or 514 nm light; most of them emit light at λ=512–554 nm (compounds 1 q and 1r at λ=576 and 589 nm in methanol, respectively) and have high fluorescence quantum yields in solution (up to 98 %), relatively long excited‐state lifetimes (>3 ns) and are resistant against photobleaching, especially at high laser intensities, as is usually applied in confocal microscopy. Sulfonation of the xanthene fragment with 30 % SO3 in H2SO4 is compatible with the secondary amide bond (rhodamine‐CON(Me)CH2CH2COOH) formed with MeNHCH2CH2COOCH3 to providing the sterically unhindered carboxylic group required for further (bio)conjugation reactions. After creating the amino reactive sites, the modified derivatives may be used as fluorescent markers and labels for (bio)molecules in optical microscopy and nanoscopy with very‐high light intensities. Further, the new rhodamine dyes are able to pass the plasma membrane of living cells, introducing them as potential labels for recent live‐cell‐tag approaches. We exemplify the excellent performance of the fluorinated rhodamines in optical microscopy by fluorescence correlation spectroscopy (FCS) and stimulated emission depletion (STED) nanoscopy experiments. 相似文献
19.
Chemical and Toxicological Investigations of a Previously Unknown Poisonous European Mushroom Tricholoma terreum 下载免费PDF全文
Xia Yin Dr. Tao Feng Prof. Jian‐Hua Shang Yun‐Li Zhao Fang Wang Zheng‐Hui Li Ze‐Jun Dong Prof. Dr. Xiao‐Dong Luo Prof. Dr. Ji‐Kai Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(23):7001-7009
The established tradition of consuming and marketing wild mushrooms has focused attention on mycotoxicity, which has become a global issue. In the present study, we describe the toxins found in a previously unknown poisonous European mushroom Tricholoma terreum. Fifteen new triterpenoids terreolides A–F ( 1 – 6 ) and saponaceolides H–P ( 8 – 16 ) were isolated from the fruiting bodies of the toxic mushroom T. terreum. Terreolides A–C ( 1 – 3 ) possessed a unique 5/6/7 trioxaspiroketal system, whereas terreolides D–F ( 4 – 6 ) possessed an unprecedented carbon skeleton. Two abundant compounds in the mushroom, saponaceolide B ( 7 ) and saponaceolide M ( 13 ), displayed acute toxicity, with LD50 values of 88.3 and 63.7 mg kg?1 when administered orally in mice. Both compounds were found to increase serum creatine kinase levels in mice, indicating that T. terreum may be the cause of mushroom poisoning ultimately leading to rhabdomyolysis. 相似文献
20.
Zhaofu Fei Holger Thnnessen Peter G. Jones Lindsey Crowe Robin K. Harris Reinhard Schmutzler 《无机化学与普通化学杂志》2000,626(8):1763-1772
The reaction of the bis‐chlorophosphines 1 a – 1 d with bis(2‐chloroethyl)amine hydrochloride in the presence of triethylamine and with various trimethylsilylamines led to a new class of bis‐phosphorus ligands 2 a – 2 c and 3 a – 3 g . 31P‐NMR studies suggested that the bis‐phosphorus ligands undergo rotation reactions about the alkyl bridge in polar solvents. Compounds 2 a – 2 c showed initially only one sharp singlet each in their 31P‐NMR spectra. After a few days at room temperature, two signals were observed. Similar results were observed for 3 a – 3 g . In the solid state, the two phosphorus atoms in 2 c are not equivalent, as was confirmed by the observation of two signals in the solid state 31P‐NMR spectrum. Oxidation reactions of 2 a – 2 c by the hydrogen peroxide‐urea 1 : 1 adduct (NH2)2C(:O) · H2O2 led to the formation of the corresponding phosphoryl compounds 4 a – 4 c . Reaction of 2 a and 3 a with Pt[COD]Cl2 (COD = 1.5‐Cyclooctadiene) furnished the complexes 5 and 6 . The NMR spectra suggested that the two chlorine atoms are in cis position. X‐ray structure analyses were conducted for 2 a , which exhibits twofold symmetry; 2 c , which is linked into dimers by hydrogen bonds C–H…O; and 6 , confirming the cis configuration. 相似文献