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1.
Eleven new melampolides, tetraludins D-N, were isolated from aerial parts of Tetragonotheca ludoviciana. Tetraludins D and E, F and G, J and K, and L and M represented epimeric pairs which differed only at one chiral centre of the five-carbon ester side chain at C-8. In benzene-d6, the 1H NMR spectra of the diastereomeric pairs of melampolides exhibited well-separated signals in particular for the absorptions due to the ester side chains that differed in chirality. 相似文献
2.
Nineteen flavonoids were isolated from Artemisia ludoviciana var. ludoviciana, including a new 2′- hydroxy- 6-methoxyflavone, 5,7,2′,4′-tetrahydroxy-6,5′-dimethoxyflavone. The known compounds include quercetagetin 3,6,3′,4′-tetramethyl ether, eupatilin, 5,7-dihydroxy-3,6,8,4′-tetramethoxyflavone, luteolin 3′,4′-dimethyl ether, jaceosidin, 5,7,4′-trihydroxy-3,6-dimethoxyflavone, tricin, hispidulin, chrysoeriol, kaempferol 3-methyl ether, apigenin, axillarin, eupafolin, selagin and luteolin together with three flavones which were previously isolated for the first time from Artemisia frigida: 5,7,4′-trihydroxy-6, 3′,5′-trimethoxyflavone, 5,7,3′-trihydroxy-6,4′,5′-trimethoxyflavone and 5,7,3′,4′-tetrahydroxy-6,5′- dimethoxyflavone. 相似文献
3.
Artemisia ludoviciana Nutt. ssp. albula (Woot.) Keck, a member of the vulgaris complex, contains a sesquiterpene lactone, ludalbin, which is 8-α-acetoxydouglanine. 相似文献
4.
From three of five investigated species of Griselinia a new iridoid glucoside, griselinoside, was isolated. It was found to be present also in foliage of Aralidium pinnatifidum and Toricellia angulata, accompanied in the former by aralidioside another novel iridoid glucoside. The structures and absolute configurations of the two iridoids were elucidated by NMR spectroscopy and chemical conversions. From G. littoralis and T. angulata the glucosides magnolioside and syringoside respectively were isolated. 13C NMR spectra are given for thirteen iridoid derivatives. 相似文献
5.
John D. Bacon Lowell E. Urbatsch Louis H. Bragg Tom J. Mabry Paula Neuman David W. Jackson 《Phytochemistry》1978,17(11):1939-1943
Fifteen flavonols, five aglycones and ten glucosides were isolated from the four species of Tetragonotheca, T. repanda, T. helianthoides, T. texana and T. ludoviciana. Included among the isolated flavonols are four previously unreported 7-O-glucosides, 6-hydroxykaempferol 7-O-glucoside, 6-hydroxykaempferol 6-methyl ether 7-O-glucoside, quercetagetin 6,3′-dimethyl ether 7-O-glucoside and quercetagetin 3,6-dimethyl ether 7-O-glucoside. 相似文献
6.
Further investigation of the minor terpenoids in Helianthus niveus subsp. canescens and H. argophyllus afforded two known 12,8-fused sesquiterpene lactones, 3-acetylchamissonin and simsiolide as well as one new germacranolide, argophyllin C. Identification and structure elucidation of these lactones by 1H NMR and chemical transformations are described. 相似文献
7.
Desacetyleupaserrin, eupaserrin and two new germacranolides, mollisorin-A and mollisorin-B, were isolated from H. mollis. 1H NMR and 13C NMR data and chemical interconversions of the four germacranolides are described. 相似文献
8.
(25R)-Isonuatigenin, a 5-spirosten-3β,25-diol, was isolated from aerial parts of Vestia lycioides. Its structure was elucidated mainly by 1H NMR and 13C NMR spectroscopy. A mixture of (25R)-nuatigenin and (25S)-isonuatigenin was also characterized. This is the first report on the natural occurrence of the two (25R)-isomers. 相似文献
9.
The structures of isoflavidinin and iso-oxoflavidinin, two new modified 9, 10-dihydrophenanthrenes of the orchids Pholidota articulata, Otochilus porecta and O. fusca have been established. 13C NMR spectral analysis of isoflavidinin acetate was made to confirm its structure. 相似文献
10.
Two new diterpenes, 3α-angeloyloxy-18-hydroxy-13-furyl-ent-labda-8(17)-ene and 3α-hydroxy-18-angeloyloxy- 13-furyl-ent-labda-8(17)-ene and an only recently reported third diterpene, 3α, 18-dihydroxy-13-furyl-ent-labda-8(17)-ene, were isolated from the leaves of Gutierrezia grandis. Their structures were determined by mass spectral, IR, 1H NMR and 13C NMR data was well as chemical evidence. 相似文献
11.
Yusuke Kinoshita Motoki Kayama Yuichiro Kashiyama Hitoshi Tamiaki 《Bioorganic & medicinal chemistry letters》2018,28(6):1090-1092
Divinyl-132,173-cyclopheophorbide-a enol was in vivo produced as a metabolite of divinyl-chlorophyll-a by protists and in vitro prepared by the intramolecular cyclization of methyl divinyl-pyropheophorbide-a, one of the divinyl-chlorophyll-a derivatives. The 1H NMR spectra in CDCl3 showed that the obtained product took exclusively its enol form in the solution. The intramolecular cyclization of chlorin π-system at the C132 and C173 positions affected the optical properties of such chlorophyll derivatives including the non-fluorescent emission of the enol. 相似文献
12.
Tsuneatsu Nagao Hideaki Otsuka Hiroshi Kohda Tomohiro Sato Kazuo Yamasaki 《Phytochemistry》1985,24(12):2959-2962
The absolute configurations of 2-O-β-D-glucopyranosyl-7-methoxy-1,4(2H)-benzoxazin-3-one and three congeners isolated from Coix lachryma-jobi var. ma-yuen were determined by X-ray analysis and chemical correlation as the 2R type. 13C NMR spectra of all congeners and coixol were fully assigned. 相似文献
13.
The roots of Argyranthemum adauctum ssp. jacobaeifolium, a rare endemic from Gran Canaria, afforded two new derivatives of the aromatic acetylene frutescin and 8-isovaleryloxymyrcene, while the aerial parts gave a new bisabolol derivative. Furthermore several known compounds were isolated. The structures were elucidated by high field 1H NMR spectroscopy and a few chemical reactions. 相似文献
14.
Russell J. Molyneux James N. Roitman Mabry Benson Robert E. Lundin 《Phytochemistry》1982,21(2):439-443
The 13C NMR spectra of nine pyrrolizidine alkaloids of the macrocyclic diester type, seven of the corresponding N-oxides and of the parent base retronecine have been recorded and the signals assigned. The 13C NMR signals were found to be sensitive to structural variation in both the diester moiety and the heterocyclic ring system, providing useful information for structural elucidation, particularly when the 1H NMR spectra may be difficult to interpret. 相似文献
15.
Scabrogenin and deutziogenin, the stable aglycones of known iridoid glucosides scabroside and deutzioside, have been isolated from Deutzia scabra. Their structures and mutarotational equilibria were investigated by detailed analysis of 1H NMR and 13C NMR data. 相似文献
16.
The constituents of the steam volatile oils from two kinds of Allium fistulosum, A. fistulosum var. caespitosum and A. chinense, have been investigated by GC and spectral techniques (IR, UV, GC/MS, 1H NMR and 13C NMR). The compounds identified from the neutral fraction of each volatile oil included sulphides, thiolanes, alcohols, aldehydes, ketones, furanones and others. Among the sulphur compounds, dipropyl disulphide comprised ca 28% of A. fistulosum oil, ca 23% of A. fistulosum var. caespitosum oil and ca 30% of A. chinense oil. A. fistulosum oil was characterized by a large quantity of tridecan-2-one (ca 52%) and 2,3-dihydro-2-octyl-5-methylfuran-3-one (ca 16%). Also, a large amount of 2,3-dihydro-2-hexyl-5-methylfuran-3-one (ca 20%) was isolated from A. chinense oil. 相似文献
17.
The investigation of the roots of the four Tetragonotheca species, T. ludoviciana, T. repanda, T. texana and T. helianthoides, resulted in the isolation of the known heptadeca-2-(Z)-8,10-(E)-16-tetraene-4,6-diin-1-ol and its aldehyde derivative from all four species. Aerial parts of T. ludoviciana also contained the acetate of the latter compound as a minor constituent and provided three new melampolide-type sesquiterpene lactones, tetraludin A, B and C. 相似文献
18.
In addition to a known derivative, five new coumarin-hemiterpene ethers were isolated from the leaves of Artemisia laciniata, A. armeniaca and A. tanacetifolia and identified by 1H NMR and, in part, by 13C NMR spectroscopy. The coumarin patterns are characterized particularly by compounds with a hydroxylated and saturated isoprenoid unit attached to oxygen at the C-8 position and by 5,7,8-trioxygenated derivatives. The chemotaxonomic significance of the coumarin-terpenoid ethers within Artemisia is discussed. 相似文献
19.
Two new flavonol glucosides have been identified in Ephedra alata, namely, herbacetin 8-methyl ether 3-O- glucoside-7-O-rutinoside and herbacetin 7-O-(6″-quinylglucoside). The known flavonoids vicenin II, lucenin III, kaempferol 3-rhamnoside, quercetin 3-rhamnoside and herbacetin 7-glucoside were also found. The structure of the isolated compounds was determined mostly by FABMS and 1H NMR spectroscopy. The final structure of the new compounds and of herbacetin 7-glucoside was confirmed by 13C NMR spectroscopy. 相似文献
20.
Oliver Seiler 《Inorganica chimica acta》2004,357(6):1955-1958
Reaction of tetramethoxysilane with 1,3-diphenylpropane-1,3-dione and benzilic acid (molar ratio 1:2:1) in tetrahydrofuran/n-pentane yielded the neutral heteroleptic hexacoordinate silicon(IV) complex [benzilato(2−)-O1,O2]bis[1,3-diphenylpropane-1,3-dionato(1−)-O,O]silicon(IV) (5). Compound 5 was structurally characterized by single-crystal X-ray diffraction, solid-state VACP/MAS NMR spectroscopy (29Si), and solution NMR spectroscopy (1H, 13C, 29Si). The chiral silicon(IV) complex, with its octahedral SiO6 coordination polyhedron, is configurationally stable in solution on the NMR time scale (solvent: CDCl3; maximum temperature studied: 58 °C). 相似文献